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Displacement sensor is the key component of the magnetic levitation system. Reducing complexity and improving reliability of the sensor circuits are very important to mass production of magnetic levitation devices. In this article, an improved driver circuit of eddy current sensor is proposed. In order to generate a stable oscillating source with high stability and good precision of frequency, a crystal oscillator circuit with power boost is used to replace the traditional Colpitts oscillator circuit. The improved modulation circuit is composed of passive components with a simple structure for improving reliability. The parameters design method of the modulation circuit is analyzed in detail, which greatly affects the sensitivity and linearity of the sensor. The experimental results show that the designed eddy current sensor has good linearity (1.12%) and sensitivity (2.14 V/mm), and it can ensure the stable operation of the magnetic levitated turbomolecular pump at the rated speed.

This brief presents two dual-band low noise amplifiers (LNAs) in Q/V -band fabricated in 0.18- ${\mu }\text{m}$ SiGe BiCMOS technology. The developed LNAs function over the dual (44/60 GHz)-band with an integrated filtering function and achieve peak power gain of 19.1 dB with minimal gain imbalance of less than 0.2 dB between the two bands. The achieved 3-dB bandwidths are more than 6 GHz for each band of the two LNAs with the lowest measured noise figure of 5.6 dB in the targeted frequency bands. The synthesized Q-enhanced metamaterial transmission line structures proposed in this brief contribute a dual-band operation at 44/60 GHz with a rejection of more than 30 dB between the two bands. The Colpitts style negative generation circuit is utilized in conjunction with composite right/left-handed metamaterial transmission line and its dual structure, which is unprecedented, to realize multi-band millimeter-wave integrated circuits.

We have designed and developed a compact, contactless, chipless, high frequency wireless passive LC pressure sensor tag capable of measuring pressure from 0 Pa to 60 kPa. The LC pressure sensor tag design consists of a parallel combination of a planar inductor and a pressure sensitive interdigitated capacitor (IDC). The readout or signal detection and signal processing system combines a Colpitts oscillator, different electronic circuits, and a microcontroller-based signal processing unit. Operation of the sensor is based on mutual coupling of the inductor of the LC pressure sensor tag and the oscillation coil of the Colpitts oscillator. The pressure sensitive IDC consists of interdigitated electrodes and a melamine foam containing poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as an elastic pressure sensitive dielectric material. When pressure is applied to the LC pressure sensor tag, the capacitance of the IDC sensing element changes, which changes the resonance frequency. Because the LC pressure tag and the inductor of the oscillator are inductively coupled, the frequency of oscillation of the Colpitts oscillator changes. The LC pressure sensor has a highly sensitive sensing response of 762.65 Hz/kPa and a linear sensing performance over a wide measurement range, with a correlation coefficient ( $\text{R}^{\sf 2}$ ) of 0.997. The LC pressure sensor tag is lightweight, highly sensitive, inexpensive to fabricate, and has good repeatability and stability values in the percentage of 2.8 and 1.1, respectively.

An improved topology for sub-THz radiation detection realized in 65 nm CMOS, including an on-chip antenna and using zero biasing is presented in this article. The topology is based on a differential Colpitts topology working in reverse-mode and leverages the nonlinearity with respect to vDS in subthreshold operation to rectify. The use of tuned inductors at the gates and sources of the transistor core create degenerative resonance feedback, which further enhances the responsivity while working with zero bias eliminates 1/ f noise to improve the NEP. Measurements demonstrated a voltage responsivity as high as 2 kV/W with a 3 dB RF BW of at least 50 GHz centered at 315 GHz and a record NEP of down to 3.5 pW/√Hz, verified both at zero-IF and using chopping from 0.5 Hz up to 2 kHz. The chip occupies an area of 0.165 mm2 including pads.

A GaAs Colpitts voltage controlled oscillator with low phase noise is presented in this brief. Firstly, the ${g} _{\mathrm{ m}}$ -boosting technique realized by an inductor located at the emitter of heterojunction bipolar transistor is applied to relax the oscillation start-up requirements and speed up the oscillation. Moreover, a Collector-Emitter cross-coupling capacitor is adopted to improve the loaded quality factor and oscillation amplitude of the tank by reducing the transformer ratio, which improves the phase noise in turn. Finally, in proof of the concept, a voltage controlled oscillator prototype is fabricated and designed in 2- ${\mu }\text{m}$ GaAs HBT process. The measured results demonstrate a phase noise of −137.44 dBc/Hz at 1MHz offset with figure of merit of −192dBc/Hz and a tuning frequency bandwidth from 3.25 to 3.4GHz. Compared with the conventional Colpitts voltage controlled oscillator, the phase noise of the proposed voltage controlled oscillator with ${g} _{\mathrm{ m}}$ -boosting and Collector- Emitter cross-coupling techniques has been improved 6.67 dB.

In this the paper, we consider an approach for increasing of density of field-effect transistors, which comprised of an enhanced swing differential Colpitts oscillator. Based on this approach, we describe manufacture of this oscillator in a heterostructure with a specialized structure. Doping of some specific regions of the considered heterostructure should be done by using diffusion type of doping or by ion type of doping. After the doping, dopant and radiation defects will be annealed by the used optimized procedure. We also will consider an approach of decreasing of mismatch-induced stress value in this heterostructure. We introduce an analytical approach for modeling of mass and heat transport in multilayer structures during manufacturing of integrated circuits taking into account mismatch-induced stress.

This article describes a wideband low-noise frequency synthesizer implemented in 0.13- $\mu \text{m}$ SiGe BiCMOS process for 5G millimeter-wave applications. To extend the frequency range while reducing the phase noise, a fundamental voltage-controlled oscillator (VCO) array including four Colpitts VCO cores with switchable bias circuits is adopted in the proposed frequency synthesizer. A ring-oscillator-based injection locked frequency divider is utilized as the wideband divide-by-2 prescaler, and its bandwidth is optimized based on a new injection-locked behavior model. This fabricated frequency synthesizer can be locked in a range from 23 to 36.8 GHz (46.2%) by a 100-MHz step. It achieves a phase noise of −94.7 dBc/Hz at the 1-MHz offset and an output power of −3.5 dBm measured at 36.8 GHz. The chip consumes 360.6 mW from 3.3 and 1.8 V supplies and has an area of $2.7\times3.1$ mm2.

In this paper, we consider an enhanced swing differential Colpitts oscillator based on field-effect transistors. We introduce an approach to increase density of these field-effect transistors based on the analysis of mass transport. To illustrate the approach, we consider manufacturing of these transistors in heterostructure with specific configuration: substrate; epitaxial layer with several sections, which were manufactured using other materials; buffer layer between the substrate and the epitaxial layer. The considered sections should be doped by diffusion or by ion implantation after manufacturing of the heterostructure. After the doping, the infused dopant and radiation defects (radiation defects were generated during ion implantation) should by annealed framework optimized scheme. We also consider the possibility to decrease mismatch-induced stress in the considered heterostructure during manufacture of the considered oscillator. To make analysis of mass transport in the above heterostructures during the manufacture of the oscillator, we introduce an analytical approach. The approach gives a possibility to analyze mass transport in multilayer structures without crosslinking of solutions on interfaces between layers; to take into account spatial and temporal variation of parameters of linear and nonlinear mass transport at one time with account mismatch-induced stress.

A millimeter-wave (mm-wave) voltage-controlled inductor (VCI) that is based on a series inductor–capacitor tank and that achieves large ratios of maximum to minimum inductance is proposed. For demonstration, a VCI with an inductance ratio of 4 is employed in a 22-nm CMOS silicon on insulator (SOI) Colpitts third-order-harmonic-extracted injection-locked (IL) oscillator (ILO) operating from 112.5 to 135 GHz. The ILO dc power consumption is 13 mW with a 1.2-V supply but is reduced to 5.6 mW with a 0.8-V supply when a 2-V back-gate voltage is applied. Due to the proposed VCI, the core of the mm-wave ILO occupies only 0.018 mm 2, the tunable operating range is ≥16%, and the added phase noise (PN) (~10 dB) is close to the theoretical prediction (20log(3) dB).

This letter presents a negative conductance ( $G_{m}$ )- and swing-enhanced Colpitts voltage-controlled oscillator (VCO) based on optimization of the capacitance ratio. In the proposed VCO structure, a current source typically used in conventional VCOs is replaced with an inductor to increase the output voltage swing. A current-reuse configuration is also adopted to decrease power consumption. Theoretical analyses and simulations show that the devised VCO with an optimized capacitance ratio exhibits enhanced $G_{m}$ and swing when compared to a conventional VCO. Measurements revealed a phase noise of −129.67 dBc/Hz at a 1-MHz offset frequency from the 2.2-GHz carrier, while power consumption was 2.2 mW from a 1.2-V supply voltage. This resulted in a figure-of-merit of −193.1 dBc/Hz. The proposed device was implemented using a 65-nm CMOS process.

Nowadays, terahertz and sub-terahertz frequencies are experiencing a significant interest from both academic and industrial world, since they offer a wide and unused spectrum available for different applications, as high-throughput communications, efficient imaging systems and medical uses. In this work an innovative sub-THz voltage-controlled oscillator (VCO) realized with a 130-nm SiGe process is proposed and described in detail. The technology is the SG13G2 bipolar-complementary-metal-oxide-semiconductor (BiCMOS) provided by IHP foundry. The signal source is conceived for high-resolution THz imaging camera; at design level it has been defined with a push-push architecture and adopts an oscillator core based on a Colpitts topology. State-of-the-art performance has been obtained thanks to the proposed design choices that are uncommon at these frequencies, as for instance, the VCO output taken from the common base node, the use of varactors in anti-series connection and the possibility to define a double output at different harmonic frequencies. These, as well as other innovative expedients, allow to simplify the integration at system level and to achieve compact sizes, very low power consumption and almost constant output power level over the full tuning bandwidth. A relative tuning range of about 5.5% has been obtained around a central frequency of 330 GHz, while the output power is about − 8 dBm with a maximum variation of 0.4 dB. Also the phase noise of − 110 dBc/Hz at 10 MHz offset is very promising. Measurements over different chip samples demonstrate the robustness of the proposed solution and the reliability of the design.

A wide-band push–push common-collector Colpitts voltage-controlled oscillator (VCO) using impedance peaking network and gain enhancing technique is proposed in this work. The impedance peaking network is introduced to increase the coupling factor of the differential inductor in the inductor capacitor (LC) tank without sacrificing the quality factor. The impedance peaking technique could guarantee the push–push VCO unconditionally oscillating in a differential mode without degrading the phase noise performance. The gain enhancing technique employs an LC resonator in series with the emitter degeneration resistor in the common-collector amplifier in the VCO core to improve the VCO oscillating amplitude and then improve the phase noise performance. The proposed VCO oscillates at around 20 GHz with >10.5% frequency tuning range from 18.9 to 21.4 GHz across temperature from −40 to 125°C. The measured phase noise is lower than −107 dBc/Hz at 1 MHz offset across the entire working temperature (−40 125°C). The whole VCO dissipates 45 mA under 3.3 V power supply, and the typical figure of merit is around −177.92.

The year 2018 marked 100 years since the introduction of a class of oscillatory circuits called Colpitts oscillators. Few other electronic circuits have survived for such a long time and affected the electronic technology as the Colpitts oscillator. Today, Colpitts oscillators are found in both communication systems and digital circuits as clock and frequency generators. In this paper, we provide a comprehensive overview over the development of the Colpitts oscillator, from the simple vacuum tube oscillator patented by Colpitts in 1918, to state of the art MEMS oscillators operating at high GHz region in today?s modern electronics. We review different types of Colpitts oscillators, including singleended, differential, complementary, gm-boosted and introduce a timeline for the development of these circuits.

This letter presents a 24-MHz ultralow-power and low-phase-noise complementary Colpitts crystal oscillator. Class-C operation is realized by biasing the oscillator always in the weak-inversion region with the proposed circuit. A Langasite-type CTGS (Ca3TaGa3Si2O14) crystal resonator, with the characteristics different from those of quartz (SiO2), helps to reduce the startup time to less than 1 ms. An injected- ${g} _{m}$ -booster is implemented to speed up the oscillation further. Prototype chips in 65-nm CMOS were evaluated with CTGS and quartz resonators. With each type, the lowest steady-state power consumption and the best jitter FoM have been achieved. With the CTGS resonator, the startup energy as low as 10 nJ has also been achieved.

In this letter, an improved balanced Colpitts voltage-controlled oscillator (VCO) with a collector–emitter cross-coupled capacitors is presented. The proposed Colpitts structure can introduce a more robust oscillation startup condition. The noise-shifting technique is used to enhance the loaded quality factor of the tank, which improves the phase noise in turn. In addition, three-bit switches composed of enhancement-mode high-electron mobility transistors (E-HEMTs) are utilized to expand the tuning range and reconfigurability of the proposed VCO. In proof of the concept, a VCO prototype is fabricated in a GaAs BiHEMT [enhancement- and depletion-mode high-electron mobility transistor (E/D-PHEMT)] process. The measured results demonstrate the best phase noise of −139.46 dBc/Hz at 1-MHz offset. To the best of our knowledge, this is the lowest phase noise among the reported ones fabricated on-chip with a similar frequency band, and it achieves a wide tuning frequency bandwidth of 21% (2.65–3.27 GHz) with peak figure of merit (FoM) of −192.26 dB and FOMT of −198.8 dB.

This article proposes a low voltage, optimized tuning range and phase noise voltage-controlled oscillator (VCO) adopting colpitts architecture and using gm boosting technique for 5.8 GHz applications. Measured consequences of the Colpitts VCO circuit exhibit the tuning range of 5.29 to 6.07 GHz as well as phase noise of -123.4 dBc/Hz at 1 MHz frequency offset and product power of -6.67dBm under 5.73 GHz. The power consumption of the core circuit is 4.7mW from supply voltage of 1V. The proposed overall chip (die size = 0.6 x 0.6 mm2) is fabricated in tsmc 0.18μm CMOS 1P6M process.

A free space 252 GHz quasi-optical emitter-detector pair (optopair) is implemented in standard Si CMOS technology. The THz source consists of a voltage-controlled differential field-effect-transistor (FET) based Colpitts oscillator emitting at the third harmonic with total radiated power -11.1 dBm and 35 mW DC power consumption. The detector is a resonant-antenna-coupled FET-based power detector for quasi-optic coupling through the substrate lens. The detector exhibits a minimum optical noise equivalent power as low as $22{\text{pW}}/\sqrt {{\text{Hz}}} $ at 252 GHz. The system reveals 61.7 dB power signal to noise for 1 Hz equivalent noise bandwidth in the direct detection regime. The practical application of the pair for two-dimensional imaging is also demonstrated.

A low voltage, and phase noise Colpitts voltage-controlled oscillator (VCO) with even harmonic mixer and balun for 5.8-GHz-band application is proposed and implemented in tsmc 0.18-um CMOS process. The proposed VCO has two main features; 1.0 V low supply voltage, and using two single-ended complementary Colpitts LC circuits. Measured results achieve tuning range of 5.17 to 5.97 GHz, corresponding to 14.6%, phase noise of -117.57dBc/Hz at 1 MHz offset from 5.8 GHz while the tuned control voltage is adjustable from 0 to 1.0V and output power of -8.97 dBm at 50$- \Omega$ termination. The power consumption of core circuit is 3.58 mW and the VCO chip dimension including pads is 0.40 (0.71x0.56)mm2. The proposed even harmonic mixer with four phase local oscillator switching mixer adopts a conversion power gain of 0.98 to 5.76 dB, LO power of -9dBm, input $\mathrm{P}_{{\mathrm {1dB}}}$ of -12 to- 17 dBm, IIP3 of -10.7 to 0.16 dBm, LO-RF isolation of 34 dB, respectively.

Inductive proximity sensors are low-cost and versatile detectors achieving resolutions in the nm and sub-nm range. Their typical working frequency ranges from tens of kHz to a few MHz. Operation at higher frequencies is considered as a possible route for the improvement of the performance. Here we report on the design of two microwave inductive proximity sensors based on LC-oscillators operating at 500 MHz and 10 GHz, respectively. Both detectors are based on a frequency-encoded architecture, leading to an intrinsic robustness against interference and signal attenuation. The 500 MHz oscillator is composed of an off-chip resonator with a planar coil having a diameter of 6.4 mm and a CMOS integrated cross-coupled transistor pair. It achieves a frequency noise floor of 0.15 Hz/Hz1/2 (above the 1/f corner frequency of 6 kHz), which leads to a distance resolution of 0.1 pm/Hz1/2 at 110 μm from the coil. The integrated noise in the 1 mHz to 1 kHz bandwidth corresponds to a distance resolution of 45 pmrms. The 10 GHz oscillator is a fully integrated CMOS differential Colpitts with a planar coil having a diameter of 270 μm. It achieves a frequency noise floor of 2 Hz/Hz1/2 (above the 1/f corner frequency of 10 kHz) which leads to a distance resolution of 0.3 pm/Hz1/2 at 70 μm from the coil. The integrated noise in the 1 mHz to 1 kHz bandwidth corresponds to a distance resolution of 100 pmrms.

This paper describes a 22-to-36.8 GHz low phase noise Colpitts voltage-controlled oscillator (VCO) array using 0.13-μm SiGe BiCMOS technology. The VCO array consists of four Colpitts VCO cores and three millimeter-wave (MMW) selectors. In the VCO core, in order to achieve the best phase noise and power consumption trade-off, an optimization method based on symbolic expressions is presented. In a further research, a switchable bias current technique is proposed to achieve lower phase noise. The MMW selectors are designed to select the desired VCO core and cover the whole frequency band with sufficient output power. The fabricated VCO array features a wide tuning range of 50.3%, low phase noise between −100.7 dBc/Hz and −95.3 dBc/Hz at 1 MHz offset and high output power of 4.5 dBm, which results in the FOMT between −183.2 dBc/Hz and −177.8 dBc/Hz.

A Colpitts voltage-controlled oscillator (VCO) is presented for low-power and low-phase-noise applications. The current efficiency of the proposed VCO is improved through ${g} _{{m}}$ -enhanced and current-reuse techniques. In addition, a clover-shaped inductor is employed to mitigate electromagnetic interference (EMI) effects. The VCO is implemented in a 0.18- ${ \mu }\text{m}$ CMOS process and is shown to operate at frequencies of 2.34 to 2.55 GHz with a tuning range of 8.6%. The prototype has a power dissipation of 1.4 mW and achieves a phase noise of −122.85 dBc/Hz at a 1 MHz frequency offset.

The oscillator architecture is proposed to reduce the close-in phase noise as well as power consumption. The proposed Colpitts oscillator removes the current source which is the main source of the 1/ $f$ noise conversion. The removal of the current source is compensated by using the transformer and cross-coupled capacitors. The 2-GHz film bulk acoustic resonator (FBAR) is used for the high Q frequency selective elements in the oscillator design. According to measurement results, this FBAR-based oscillator shows $\geq$ 10 dB reduction in close-in phase noise. Specifically, 12-dB lower phase noise is achieved at 100 Hz offset frequency. Measured power consumption is 350 uW, which is almost half of the conventional Colpitts oscillator using same FBAR device.

This paper presents an architecture for differential Colpitts voltage-controlled oscillators (VCOs) in complementary metal–oxide–semiconductor (CMOS) that utilizes three design techniques to extend the tuning range (TR) of the VCO, while maintaining a low phase noise (PN) and a low power consumption. First, a switched-capacitor bank based on a variable capacitive feedback technique is introduced to achieve a wide TR with a minimal PN degradation. Second, a $G_{m}$ -boosting technique using interstage inductors is employed to lower the power consumption and relax VCO startup issues. Third, a dynamic forward-body self-biased technique is used to further reduce the power consumption and PN of the proposed structure. As a proof of concept, a 26.3-GHz differential Colpitts VCO is designed and fabricated in a 65-nm CMOS process. Based on the measurement results, the VCO achieves a PN of −122.1 dBc/Hz at 10-MHz offset from the center frequency, and a TR of 20%. The circuit consumes 2.3 mW from a 1-V supply and excluding the pads occupies a 0.22 mm2 of silicon area. Compared to the recently published CMOS VCOs within the same frequency range, the proposed VCO simultaneously achieves a wide TR, low power dissipation, and low PN, resulting in a figure of merit (FOM) and FOM incorporating the TR (FOM $_{T}$ ) of −187 and −193 dBc/Hz at 10-MHz offset from the center frequency, respectively.

A balanced Colpitts voltage controlled oscillator (VCO) topology with its two implementations in a GaAs heterojunction bipolar transistor (HBT) process is introduced in this paper. A detailed analysis of phase noise, originating from the work by Hajimiri and Lee, is given, which depicts a specific outline of the phase noise generation mechanisms in GaAs HBT based harmonic oscillators including LC cross coupled/Colpitts/class C VCOs. In addition, phase noise expressions for HBT based VCOs are derived, compared and act as an optimization tool in oscillator designs. The theoretical analysis of phase noise is authenticated with two balanced Colpitts VCOs with their respective center oscillation frequencies of 850 MHz and 1670 MHz, which are fabricated in a 2 µm GaAs HBT H20HL process. Measurement results show a phase noise of − 139 dBc/Hz at 1 MHz offset from an 850 MHz carrier and a phase noise of − 134 dBc/Hz or less at 1 MHz offset from a 1700 MHz carrier. The output power variation is less than 0.5 dBm over the tuning range. A relatively good match between numerical simulation and measurements is observed.

The generation of precise linear frequency modulation is a critical requirement for millimeterwave automotive radars. This paper presents the analysis and design of a CMOS 75.5 - 82.5 GHz monotonically linear digitally controlled oscillator (ML-DCO) fulfilling the requirements of the 77 GHz automotive radar. Non-linear large varactors are avoided. Linear coarse, intermediate, and fine-tuning ranges are achieved by arranging the available minimum Metal-Oxide-Metal (MoM) capacitor in unique configurations. Moreover, a new tuning mechanism derived from a Colpitts topology is discussed to meet the wide tuning requirements without losing linearity. The new arrangement results in a minimal amplitude variation while the ML-DCO is tuned. The coarse, intermediate, and fine-tuning steps from the post-layout simulation are 0.22, 10, and 346 KHz, respectively. The power consumption is 14 mW from a 1.2 V supply. The achieved phase-noise is -98.53 dBc/Hz at a 1 MHz offset when oscillating at 77 GHz. The ML-DCO demonstrates -185 Figure of Merit and -184 Figure of Merit for Tuning.

This article presents a low phase noise voltage-controlled oscillator (VCO) adopting optimization colpitts with gm boosting techniques. The excellent performance of the VCO core adopts a phase noise of −123.4 dBc/Hz at 1MHz offset frequency and output power of −6.67dBm from a 5.73 GHz carrier with a 4.7mW power consumption, achieving in an excellent FOM of −191.84 dBc/Hz and displayed by FOMT of −194.61 dBc/Hz. The proposed folded-current mirror mixer produces a conversion power gain of −3 ∼ 0.8 dB, input P1dB of −6 ∼ −4 dBm, IIP3 of −1.4 ∼ 1.8 dBm, LO-RF isolation of 30 dB, respectively. The overall prototypes of colpitts oscillators with folded-current mirror mixer have been fabricated in tsmc $\mathrm{0.18}\mu\mathrm{m}$ CMOS 1P6M process and implemented from supply voltage of 1V.

This work investigates the applicability of a two-stage Colpitts oscillator based on GaN high electron mobility transistors (HEMT) for wireless power transfer applications. An inductive load is used both as part of the resonance network in the oscillator and as a power transmitting coil. Simulations and experimental results using commercial GaN transistors are provided.

This paper presents three different approaches for designing dc-ac converter based on GaN transistor. The proposed circuits could be used to design the transmitter side of Wireless Power Transfer (WPT) systems. The first two approaches are based on single-stage and double-stage Colpitts Oscillators, and the third one is based on an H-bridge converter. The three circuits have been simulated using LTSpice software, then implemented on PCB boards. The whole WPT system has been implemented, cased, and tested.

Growing importance of wireless communication systems forces reduction of power consumption of the designed integrated circuits. The paper focuses on minimization of power consumption in a digitally controlled oscillator (DCO) that can be employed as oscillator in GPS/Galileo receiver. The new hybrid architecture of DCO combines good phase noise performance of a Colpitts oscillator and relaxed startup conditions of a cross-coupled differential pair oscillator. The proposed new DCO generates a quadrature signal in a current reused frequency divider. Such solution allows of the dissipated power to be reduced. The DCO has been implemented in 110 nm CMOS technology. It generates output signal in frequency range from 1.52 GHz to 1.6 GHz and consumes 1.1 mW from 1.5 V supply voltage. The measured phase noise equals −116 dBc/Hz at 1 MHz offset from 1.575 GHz output signal.

A 31.4-39.9GHz mmWave PLL synthesizer for FMCW radar applications is proposed that consists of a complementary Colpitts-assisted class-B/C VCO, a programmable quadratic-curved charge pump, and a digital chirp-code generator. The complementary Colpitts oscillator is employed to supply more negative resistance around 40GHz. The charge pump produces quadratic-curved current to keep loop bandwidth constant. The fractional-N PLL synthesizer achieves locking range of 31.4-39.9GHz, a minimum FM rms error of 160 kHz, a high-speed chirp rate of 50μs, and a maximum FM modulation bandwidth of 8.5 GHz. The PLL implemented by using 65nm CMOS process accomplishes phase noise of -89dBc/Hz at 1MHz offset from 33.9GHz and consumes 60mW.

Traffic and parking management is an important topic in modern cities. In particular open parking areas are challenging in terms of monitoring. In this paper a novel parking sensor is demonstrated, which allows detection of cars and charging of the sensor unit via one single inductor. As a proof-of-concept hardware, a small scale model of the system is implemented. For wireless power transfer the QI-standard is employed. In order to a achieve reasonable battery lifetimes the design aims to low current consumption. Power management is performed by a micro controller, which allows switching on and off external components. Furthermore detection is performed via a Colpitts oscillator circuit. The oscillation frequency of the detector lies typically around 650 kHz, whereas in the presence of a model car it increases up to 800 kHz, which is detected by a microcontroller. In the range from 14°C to 30 °C a temperature dependence of -0.4 kHz/°C is found, which is acceptable for the present system. Anyway, a temperature sensor allows a correction of thresholds for car detection. Finally, the up scaling of the model to real world size and potential problems are discussed.

This paper presents a terahertz microscope offering sub-wavelength resolution for imaging applications. The chip consists of a coupled terahertz Colpitts oscillators operating at 550GHz. It is implemented in a standard CMOS 65nm technology. A near-field sensing region between the oscillators is sensitive to external perturbation and results in a shift of the operating frequency. The far-field radiating frequency is extracted by an on-chip antenna and measured with an external harmonic mixer. The spatial resolution is verified with a micro-positioning stage.

A new fully integrated CMOS voltage-controlled oscillator (VCO) is presented. The VCO is composed of cross-coupled Colpitts negative resistance cell in shunt with a parallel-tunerd LC resonator and was implemented in 90 nm CMOS technology. The negative resistance cell uses bias-free pMOS tail for low-phase noise design. With the supply voltage of1.15 V, the VCO is tunable from 18 GHz to 20.25 GHz while the tuning voltage varies from 0V to 1.4 V. The phase noise of the VCO operating at 18 GHz is -117.34 dBc/Hz at 1 MHz offset, while the VCO draws 7.07 mA and uses 8.13 mW consumption.

A sub-1-V low-complexity crystal oscillator (XTO) is fabricated in 65-nm CMOS. The proposed crystal oscillator has lower power dissipation and better frequency accuracy performance than reported ones. The crystal oscillator is based on the conventional three-point Colpitts architecture. The oscillator core consists of a constant $g_{\mathrm{m}}$ gain stage, a quartz crystal and two load capacitors, followed by a single-ended self-biased band-passed amplifier. Experimental results show that the presented XTO generates a 12-MHz reference clock, achieving the phase noise of −95 dBc/Hz at 100-Hz offset frequency and the frequency inaccuracy of 1.2 ppm. The proposed crystal oscillator has an active area of 0.01 mm2 and the power dissipation is $32\ \mu \mathrm{W}$ from a 0.8-V supply.

This paper presents a high efficiency gate inductive feedback Colpitts Voltage Controlled Oscillator (VCO) operating near 90 GHz. It includes multi-way transformers at the load, which helps to enhance the DC-to-RF efficiency with boosted impedance and extended voltage swing through drain-buffer and drain-source magnetic couplings. The proposed VCO is fabricated in a 65-nm CMOS process, and showed an oscillation frequency tuning range of 87.5-92.0 GHz (4.5 GHz). Over the frequency range, the output power and the dc power consumption exhibited values of −2.8 −1.7 dBm and 6-22.5 mW, respectively. The peak DC-to-RF efficiency was 9.4 %, and the corresponding phase noise was −107.4 dBc/Hz at 10-MHz offset. The lowest phase noise at the optimum bias condition was −116.7 dB/Hz at 10-MHz offset. The chip size is 400 ⨯ 300 μm2 excluding DC and RF pads.

In this paper we present a radio frequency precision sensor on rectangular spirals with the opposite direction of winding. The sensor is purposed to control and measure the gap to a flat metal surface. The sensor model was created using CST Studio Suite software. Using this model, we obtained relation between the gap width and change of electrodynamic parameters of the sensor. A schematic diagram of the sensor's measuring generator based on a modification of the Colpitts LC-generator was developed, and its characteristics were obtained in the PSpice. This paper also indicates the advantages of using proposed sensor as a base for various devices and systems for monitoring, measurement and controlling of physical quantities and parameters of technological processes.

Nowadays are being held intensive researches involving the use of deterministic chaos in communication systems. Indeed chaotic oscillations in such systems serve as a carrier of information signals, and means of encryption, both in hardware and in software. This work is devoted to the complex analysis of the practical implementation of a chaotic secure communication system. The generalized synchronization as a synchronization response was selected. The circuit implementation of a modified Colpitts oscillator as a source of chaos was proposed. We also discussed questions of modeling chaotic oscillations and, in this context, analyzing the differences between chaotic, pseudo-chaotic and pseudo-random oscillations.

This paper presents an 86-97 GHz transmitter (TX) using a wideband voltage-controlled oscillator (VCO) operating in 21.5-26 GHz range and frequency quadrupler (FQ) fabricated in SiGe BiCMOS technology. The VCO implements a self-buffered common-collector Colpitts topology with binary-weighted varactor ladder for low VCO gain ( $K_{VCO}$ ) and wide tuning range. Use of high-Q passive components and low-noise heterojunction bipolar transistors (HBT) results in worst-case phase noise of -92.8 dBc/Hz at 1MHz offset from the carrier. The VCO is loaded by a low-loss transformer that splitts the signal between frequency prescaling and multiplying blocks. The prescaler comprise three divide-by-two circuits (DTC) based on D flip-flops (D-FF) providing adequate feedback signal for an external phase-locked loop (PLL). The multiplying section consists of two cascaded Gilbert-cell frequency doublers driving a W-band power amplifier (PA). The TX achieves 0.2dBm output power at 92GHz and more than -2.8dBm in 86-97 GHz range consuming 60mA from 3.3V supply. The chip occupies 0.755 mm2 silicon area.

A customized structure of the Colpitts VCO for the 5G millimeter band is presented in this paper, this structure has a very low phase noise level compared to other structures published in the literature. Simulation results show that our VCO has a tuning range of 1.69 GHz around 28 GHz, an output power of 3.3 dBm and a phase noise around -123.2dBc/Hz at 1 MHz offset frequency from carrier. The VCO is designed in MMIC technology using the pHEMT transistor of PH15 process from UMS foundry.

In this chapter, we present a 300-GHz frequency synthesizer incorporating a triple-push VCO with a Colpitts-based active varactor (CAV) and a frequency divider with three-phase injection [24]. The synthesizer, implemented in 90-nm SiGe Bipolar complementary-metal-oxide-semiconductor (BiCMOS) with half of 240/315 GHz, achieves 7.9% of locking range (280.32-303.36 GHz) and generates -14 dBm of output power at 290 GHz. Based on the measurement result, the frequency -scaled phase noise of the 294.9-GHz signal is -77.8 dBc/Hz (-82.5 dBc/Hz) at the 100 -kHz (1 MHz) offset.

A complementary metal oxide semiconductormicro electro-mechanical systems (CMOS-MEMS) platform is applicable for integrating MEMS resonators and CMOS integrated circuits on a single chip. This provides a monolithic connection of MEMS with electronics. With this integration, different configurations of monolithically integrated MEMS resonators and CMOS amplifiers have been developed for commercial multi user purpose. It also provides variety of design flexibilities for resonator applications. In this paper, the design and analysis of a 2. 14MHz MEMS beam resonator for Colpitts crystal oscillator circuit is presented. A MEMS beam resonator is designed to function as an oscillator. The proposed MEMSColpitts oscillator circuit can generate 1 to 5MHz clocks, when operated in different modes. This oscillator works specifically on 2. 14MHz by macro model extraction for $9^{\mathrm{t}\mathrm{h}}$ mode only. The beam resonator requires approximately $10\mathrm{V}_{\mathrm{d}\mathrm{c}}$ to operate. The actuation was simulated in IntelliSuite (thermo-electro mechanical module). A macro model of resonator is extracted by using system model extraction (SME) and utilized in electrical circuit of Colpitts crystal oscillator. The comparison with other research works is also presented.

In this work we present a novel technique to estimate the resonance frequency of LC chipless tags (inductor-capacitor parallel circuit) with improved sensitivity and linearity. The developed reader measures the power consumption of a Colpitts oscillator during a frequency sweep. The readout circuit consists of a Colpitts oscillator with a coil antenna, varactor diodes to change the oscillator frequency, analog circuitry to measure the power consumption and a microcontroller to control the whole system and send the data to a PC via USB. When an LC tag is inductively coupled to the oscillator, without contact, a maximum power peak is found. As shown by an experimental calibration using an LC tag made on FR4 substrate, the frequency of this maximum is related to the resonance frequency. Both parameters, power consumption and resonance frequency, present an excellent linear dependence with a high correlation factor (R 2 = 0.995). Finally, a screen-printed LC tag has been fabricated and used as relative humidity sensor achieving a sensitivity of (−2.41 ± 0.21) kHz/% with an R 2 of 0.946.

This paper presents and compares two inherently different LC-VCO architectures for the down-conversion in a offset-PLL. The cross-coupled VCO architecture, which is unpopular in mmW SiGe applications, is compared to the commonly used Colpitts architecture. The two VCOs are fabricated with a supply voltage of 3.3 V in a modern 130 nm SiGe BiCMOS technology with HBTs offering an $f_{\mathrm{T}}$ of 250 GHz and $f_{\max}$ of 370 GHz. For easier characterization and stabilization in a PLL the same static divide-by-4 chain is added to both VCO chips. The main purpose of this work is the integration of a VCO as a downconverter for a offset-PLL with good phase noise and low power consumption at the same time. At an offset of 1 MHz the Colpitts VCO achieves a phase noise of −108 dBc/Hz at 56 GHz and the cross-coupled VCO achieves a phase noise of −100 dBc/Hz at 68 GHz, respectively. Relative frequency tuning ranges (rFTR) of 26% for the Colpitts type and 43.7% for the cross-coupled VCO are reached.

This paper presents a comprehensive guide to co-design piezoelectric RF-micro-electromechanical system (MEMS) resonators and CMOS for enabling voltage-controlled MEMS oscillators (VCMOs) that harness the best benefits out of both platforms. The analysis, focusing on understanding different tradeoffs among the tuning range, power consumption, gain, and phase noise, is generic to any kind of piezoelectric resonators and specific for Colpitts VCMOs. As a result of this paper, the first VCMO based on the heterogeneous integration of a high-Q lithium niobate (LiNbO3) micromechanical resonator and CMOS has been demonstrated. A LiNbO3 resonator array with a series resonance at 171.1 MHz, a Q of 410, and an electromechanically coupling factor of 12.7% is adopted, while the TSMC 65-nm RF LP CMOS technology is used to implement the feedback and tuning circuitry with an active area of $220\times 70\,\,\mu \text{m}^{2}$ . The frequency tuning of the VCMO is achieved by programming a binary weighted digital capacitor bank and a varactor that are both connected in series to the resonator. The best measured phase noise performance of the VCMO is −72 and −153 dBc/Hz at 1 kHz and 10-MHz offsets from 178.23- and 175.83-MHz carriers, respectively. The VCMO consumes a dc current of $60~\mu \text{A}$ from a 1.2-V supply while realizing a tuning range of 2.4 MHz (~1.4% fractional tuning range). Such VCMOs can be applied to enable ultralow power, low phase noise, and wideband RF signal synthesis for emerging applications in Internet of Things.

This paper presents a Colpitts oscillator-based self-starting boost converter for thermoelectric energy harvesting. An enhanced swing Colpitts oscillator with a 10-stage voltage multiplier is adopted as a startup circuit so that the minimum startup voltage of 40 mV is achieved. As a main converter, a zero-current-switching boost converter with a dead time controller achieves the maximum end-to-end efficiency of 75%. The inductor used in the Colpitts oscillator is reused in the main boost converter to minimize the use of the inductor. Implemented in a 65-nm CMOS, the proposed converter that requires only two external inductors provides a regulated output voltage of 1.1 V from a thermoelectric generator with an internal resistance of 2.2 $\Omega$ over the input range of 40–200 mV.

The development of a contactless readout system for High Frequency (HF) tags and its application to relative humidity monitoring is presented. The system consists of a Colpitts oscillator circuit whose frequency response is determined by a built-in logic counter of a microcontroller unit. The novel readout strategy is based on the frequency response change due to the inductive coupling between the coil of the Colpitts oscillator and the load impedance of a parallel LC resonator tag, as a result of the variation of the humidity sensing capacitor. The frequency is monitored with a low cost microcontroller, resulting in a simple readout circuit. This passive LC tag has been directly screen-printed on a humidity-sensitive flexible substrate. The readout circuit experimental uncertainty as frequency meter was 4 kHz in the HF band. A linear temperature drift of (-1.52 ± 0.17) kHz/⁰C was obtained, which can be used to apply thermal compensation if required. The readout system has been validated as a proof of concept for humidity measurement, obtaining a significant change of about 260 kHz in the resonance frequency of the Colpitts oscillator when relative humidity varies from 10% to 90%, with a maximum uncertainty of ±3% (±2 SD). Therefore, the proposed readout system stands as a compact, low-cost, contactless solution for chipless HF tags that avoids the use of bulky and costly equipment for the analog reading of wireless passive LC sensors., This work was supported by project CTQ2016-78754-C2-1-R from the Spanish Ministry of Economics and Competitivity. P. Escobedo wants to thank the Spanish Ministry of Education, Culture and Sport (MECD) for a pre-doctoral grant (FPU13/05032).

This paper presents two D-band frequency quadruplers (FQs) employing different circuit techniques. First FQ is a 129–171-GHz stacked Gilbert-cell multiplier using a bootstrapping technique, which improves the bandwidth and the conversion gain with respect to the conventional topology. Stacked architecture enables current reuse for the second frequency doubler resulting in a compact and energy-efficient design. The circuit reaches 3-dB bandwidth of 42 GHz, which is the highest among similar reported quadruplers. It achieves 2.2-dBm saturated output power, 5-dB peak conversion gain, and 1.7% peak DC-to-RF efficiency. The stacked FQ occupies 0.08 mm2 and consumes 22.7 mA from 4.4-V supply. Second presented circuit is a transformer-based injection-locked FQ (T-ILFQ) employing an E-band push–push voltage-controlled oscillator (PP-VCO). The VCO is a self-buffered common-collector Colpitts oscillator with a transformer formed on emitter inductors. Proposed configuration does not reduce the tuning range of the VCO, thus providing wide locking range and high sensitivity with respect to the injected signal. The T-ILFQ achieves 21.1% locking range, which is the highest among other reported injection-locked frequency multipliers. The peak output power is −4 dBm and the input sensitivity reaches −22 dBm. The circuit occupies 0.09 mm2 and consumes 14.8 mA from 3.3-V supply.

This paper presents a 1.8-mW 2.4-GHz channelized receiver for ISM-band applications. Unlike traditional ISM-band radios which typically require a phase-locked loop (PLL) for channelization, we propose a modified sliding-IF receiver architecture with a suitable local oscillator (LO) frequency plan utilizing a temperature-compensated thin film bulk acoustic-wave resonator (FBAR). This strategy completely eliminates the need for a PLL by directly dividing down the fixed FBAR oscillator frequency. An inductor-less current-reuse balun LNA is proposed allowing a low-power wideband matching as well as noise cancelling. The frequency conversion is achieved by a hybrid mixer, which stacks a switching mixer on a switched- $g_{m}$ mixer for current reuse. It also features good voltage headroom and common-mode noise rejection. The FBAR-based Colpitts oscillator achieves the phase noise of −144 dBc/Hz at 3.5-MHz offset. The measured RX gain, noise figure, and in-band IIP3 are 57.8 dB, 15.7 dB, and −18.5 dBm, respectively, without external crystal and on-chip inductors, which allows us to reduce the size and weight of the receiver system. It dissipates 0.86 mW (RX) and 0.92 mW (LO) from a single 1-V supply.

This paper studies a new dual-band CMOS class-C voltage-controlled oscillator (VCO). The oscillator consists of a dual-resonance LC resonator in shunt with two pairs of capacitive cross-coupled nMOSFETs. The proposed oscillator has been implemented with the TSMC 0.18 μm CMOS technology, and it shows a frequency tuning range with two frequency bands and a small tuning hysteresis is measured. The oscillator can generate differential signals at 2.4 GHz and 6.9 GHz and it also can generate concurrent frequency oscillation while the circuit is biased around the bias with frequency tuning hysteresis. With the supply voltage of VDD = 1.1 V, the VCO-core current and power consumption of the oscillator are 2.90 mA and 3.19 mW, respectively. The die area of the class-C oscillator is 0.9 × 0.97 mm2. Overvoltage stress is applied to the oscillator, measurement indicates the concurrent oscillation is sensitive to overvoltage stress.