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Vertical single-layer transitions operating at W-band frequencies have been developed. The designs are uniplanar, use electromagnetic coupling, and do not require via holes or air bridges. The first transition uses coplanar-waveguide-mode coupling and results in an insertion loss of better than 0.6 dB over the whole band, with a loss of 0.25 dB from 85 to 110 GHz. The return loss is better than -10 dB from 75 to 110 GHz. The second transition uses microstrip-mode coupling and results in a 0.2-dB insertion loss over the whole W-band. These transitions can prove very useful for millimeter-wave packaging and vertical interconnects. Index Terms--Integrated-circuit packaging, integrated circuits, millimeter wave, passive circuits, transmission-line discontinuities.

Mode conversion at the transition between grounded coplanar waveguide (GCPW) and microstrip line is demonstrated. Experimental results show the effect of overmoding in a conductor-backed coplanar waveguide on the transition behavior. A simple micromachining solution is used to cancel the parasitic modes triggered by the transition in the GCPW feed line. This results in an insertion loss of 0.3 dB and a return loss better than -18 dB from 75 to 110 GHz. The transition can prove very useful for millimeter-wave packaging and interconnects. Index Terms--Integrated-circuit packaging, millimeter wave, passive circuits, transmission-line discontinuities.

This paper presents the design, fabrication, and measurement of a reconfigurable quadrature hybrid coupler and a tunable low-loss reflective-type phase shifter built using the Cavendish Kinetics RF microelectromechanical systems switched capacitor devices. The quadrature coupler tunes from 1.5 to 2.2 GHz with 20–50-MHz steps, and > 20-dB reflection and isolation. The phase shifter covers 360° at 2.0 GHz with an insertion loss of 2.0 ± 0.5 dB at different phase states. The linearity measurements show that these devices can handle up to 5 W of input power at 1.8–2.2 GHz with an input third-order intercept point (IIP3) > 44 dBm} over all phase states. The measured second and third harmonic components are < -90 dBc at 30 dBm of RF input power. The application areas are in-phase shifters for micro and pico base-stations in the 1.7–2.3-GHz range. [ABSTRACT FROM PUBLISHER]

A novel coaxial stepped-impedance resonator (SIR) filter is proposed based on conventional multi-layer printed-circuit board (PCB) technology. The resonator results in a measured unloaded quality factor (Qu) of 185 at 3.7 GHz, has compact size, is self-shielded and has very low electromagnetic (EM) coupling to nearby RF circuits. The 3-D filter topology easily lends to advanced filter design with multiple transmission zeroes using cross coupling and source-to-load coupling on the top printed-circuit board layer. Two third-order fixed-band bandpass filters, and two fourth-order tunable bandpass filters are demonstrated in this technology. The fixed-band filters have an insertion loss of 1.6 dB with a fractional bandwidth of 6.5% at 3.6 GHz and occupy a size of 9\,\times\,12 mm^2. The tunable filter covers 2.1–2.9 GHz with a fractional bandwidth of 3.5%, and an insertion loss of 4.2–9.2 dB, limited by the silicon varactors. Multiple transmission zeroes are used in these designs to significantly improve the filter selectivity. Application areas are in fixed and tunable filters with very compact size and high shielding from nearby circuits for advanced communication systems. [ABSTRACT FROM AUTHOR]

This paper presents a fully integrated eight-way power-combining amplifier for 110-134-GHz applications in an advanced 90-nm silicon-germanium HBT technology. The eight-way amplifier is implemented using four-stage common-emitter single-ended power amplifiers (PAs) as building blocks, and reactive λ/4 impedance transformation networks are used for power combining. The single-ended PA breakout has a small-signal gain of 20 dB at 116 GHz, and saturation output power ( Psat) of 12.5-13.8 dBm at 114-130 GHz. The eight-way power-combining PA achieves a small-signal gain of 15 dB at 116 GHz, and Psat of 20-20.8 dBm at 114-126 GHz with a power-added efficiency of 7.6%-6.3%. The eight-way amplifier occupies 4.95 mm2 (including pads) and consumes a maximum current of 980 mA from a 1.6-V supply. To our knowledge, this is the highest power silicon-based D-band amplifier to date. [ABSTRACT FROM AUTHOR]

A 0.7–1.0-GHz reconfigurable bandpass-to-bandstop filter with selectable 2- and 4-pole responses is presented. The proposed filter can act as a 2- or 4-pole bandpass or bandstop filter by changing the coupling paths using zero-value coupling coefficients. The 4-pole bandpass filter mode also includes bandwidth control. The filter is built on a Duroid substrate with \varepsilon r=10.2 and h=25 mil. The center frequency tuning, as well as the bandpass-to-bandstop transformation and the selection of the number of poles are achieved using silicon varactor diodes and RF microelectromechanical systems switches. In the 2- and 4-pole bandpass modes, an insertion loss of 4.9–2.9 and 6.1–4.8 dB is measured at 0.71–0.99 and 0.72–1.01 GHz, respectively. The 4-pole bandpass mode also shows a bandwidth tuning of 28–85 MHz at 0.9 GHz. In the 2- and 4-pole bandstop modes, rejection levels of 24–28 and 32–41 dB are measured at 0.64–0.96 and 0.71–0.96 GHz, respectively. The application areas are in reconfigurable filters for wideband radios under high interference environments. [ABSTRACT FROM AUTHOR]

A 16-element phased-array receiver has been developed for advanced W-band automotive radars. The phased-array receiver is based on a single SiGe chip with RF beamforming capabilities, which is packaged using low-cost bond-wire techniques and attached to a 16-element linear microstrip array. The antenna results in a directivity of 29.3 dB and a gain of 28.0 dB at 77–81 GHz, and can be scanned to \pm \50^\circ in the azimuth plane in \sim \ 1^\circ steps. The packaging details are presented together with the steps taken to ensure a wideband impedance match and low coupling between the phased-array channels. Gain measurements done at 79 GHz agree well with simulations. The 16-element phased array receiver was used with a 2-element frequency-modulated continuous-wave transmitter at 76.5–77 GHz and high-resolution millimeter-wave images were obtained. The work shows that complex millimeter-wave phased arrays can be packaged using traditional bond-wire techniques, and can be a powerful solution for advanced automotive radars. [ABSTRACT FROM AUTHOR]

This paper presents low-noise amplifiers (LNA) at X- and K-band frequencies in a 0.18-\mum SiGe HBT technology. A method of noise match optimization with respect to base inductance in SiGe LNA design with large transistors is proposed. The measured X- and K-band LNAs result in 1.2- and 2.2-dB mean noise figure in their frequency bands, with an associated peak gain of 24.2 and 19 dB at 8.5 and 19.5 GHz, respectively. The measured IIP3 is -\11 and -\4 dBm at 10 and 20 GHz, for a power consumption of 32.8 mW (X-band LNA) and 22.5 mW (K-band LNA). To the authors' best knowledge, these results outperform all available CMOS designs and achieve the lowest mean noise figure at X- and K-bands in any SiGe or CMOS process. The main application areas are in low-noise receivers for terrestrial communication systems and low-cost radars. [ABSTRACT FROM AUTHOR]

An SiGe transmit–receive phased-array chip has been developed for automotive radar applications at 76–84 GHz. The chip is based on an all-RF beamforming approach and contains 8-transmit channels, 8-receive channels, and a complete built-in-self-test system. Two high-linearity quadrature mixers with an input P1\,dB of +\2.5 dBm are used and allow simultaneous sum and difference patterns in the receive mode. The chip operates in either a narrowband frequency-modulated continuous-wave (FMCW) mode or a wideband mode with > \2-GHz bandwidth. A high-linearity design results in an input P1\,dB of -\10 dBm (per channel), a system noise figure of 16–18 dB, and a transmit power is 4–5 dBm (per channel). The chip uses a controlled collapse chip connection (C4) bumping process and is flip-chipped on a low-cost printed-circuit board, and results in > \50-dB isolation between the transmit and receive chains. To our knowledge, this work represents the state-of-the-art in terms of complexity at millimeter-wave frequencies and with simultaneous transmit and receive operation for high-performance FMCW radars. [ABSTRACT FROM AUTHOR]

A beam peak and null steering multiple radiating mode based microstrip patch antenna is presented for satellite receive applications operating at L1 Global Positioning System (GPS) band. Two collocated microstrip patch antennas were designed to produce TM11 and TM21 radiating modes. These orthogonal and circularly polarized radiation patterns were combined enabling full hemispherical steering of a single beam peak and null. Using theoretical analysis and full-wave simulation, the multimode aperture was designed to operate over a 25 MHz bandwidth centered at 1.575 GHz, which covers the L1 GPS band. Impedance and radiation pattern measurements of the passive antenna aperture were in close agreement with the simulated data. Next, this antenna was integrated with an active feed network allowing full hemispherical control over the beam null position and limited beam peak scan in \approx 5^\circ increments. Using a simple calibration scheme, the measured beam peak and null elevation angles were programmed to within <10^\circ of the intended value based on simulation. Azimuthal positions were consistently offset by \approx 20^\circ from the simulated value, which could be resolved in the board layout by phase matching the transmission lines and test point locations. The antenna maintained high total efficiency >68% and low axial ratio <3 dB over all steering angles. [ABSTRACT FROM PUBLISHER]

This paper presents an in-depth study of a 45-nm CMOS silicon-on-insulator (SOI) technology. Several transistor test cells are characterized and the effect of finger width, gate contact, and gate poly pitch on transistor performance is analyzed. The measured peak ft is 264 GHz for a 30\,\times\,1007 nm single-gate contact relaxed-pitch transistor and the best f\max of 283 GHz is achieved by a 58\,\times\,513 nm single-gate contact regular pitch transistor. The measured transistor performance agrees well with the simulations including R/C extraction up to the top metal layer. Passive components are also characterized and their performance is predicted accurately with design kit models and electromagnetic simulations. Low-noise amplifiers from Q- to W-band are developed in this technology and they achieve state-of-the-art noise-figure values. [ABSTRACT FROM PUBLISHER]

A microstrip antenna with frequency agility and polarization diversity is presented. Commercially available packaged RF microelectrical-mechanical (MEMS) single-pole double-throw (SPDT) devices are used with a novel feed network to provide four states of polarization control; linear-vertical, linear-horizontal, left-hand circular and right-handed circular. Also, hyper-abrupt silicon junction tuning diodes are used to tune the antenna center frequency from 0.9–1.5 GHz. The microstrip antenna is 1 in x 1 in, and is fabricated on a 4 in x 4 in commercial-grade dielectric laminate. To the authors' knowledge, this is the first demonstration of an antenna element with four polarization states across a tunable bandwidth of 1.4:1. [ABSTRACT FROM PUBLISHER]

Two- and four-pole 0.7–1.1-GHz tunable bandpass-to-bandstop filters with bandwidth control are presented. The bandpass-to-bandstop transformation and the bandwidth control are achieved by adjusting the coupling coefficients in an asymmetrically loaded microstrip resonator. The source/load and input/output coupling coefficients are controlled using an RF microelectromechanical systems (RF MEMS) switch and a series coupling varactor, respectively. The two- and four-pole filters are built on a Duroid substrate with \varepsilon r=6.15 and h=25\ \mil. The tuning for the center frequency and the bandwidth is done using silicon varactor diodes, and RF MEMS switches are used for the bandpass-to-bandstop transformation. In the bandpass mode of the two-pole filter, a center frequency tuning of 0.78–1.10 GHz is achieved with a tunable 1-dB bandwidth of 68–120 MHz at 0.95 GHz. The rejection level of the two-pole bandstop mode is higher than 30 dB. The bandpass mode in the four-pole filter has a center frequency tuning of 0.76–1.08 GHz and a tunable 1-dB bandwidth of 64–115 MHz at 0.94 GHz. The rejection level of the four-pole bandstop mode is larger than 40 dB. The application areas are in wideband cognitive radios under high interference environments. [ABSTRACT FROM AUTHOR]

Wide-band switches and true-time delay (TTD) phase shifters have been developed using distributed microelectromechanical system (MEMS) transmission lines for applications in phased-array and communication systems. The design consists of a coplanar waveguide (CPW) transmission line (W - G = 100 [[micro]meter]) fabricated on a 500-[[micro]meter] quartz substrate with fixed-fixed beam MEMS bridge capacitors placed periodically over the transmission line, thus creating a slow-wave structure. A single analog control voltage applied to the center conductor of the CPW line can vary the phase velocity of the loaded line by pulling down on the MEMS bridges to increase the distributed capacitive loading. The resulting change in the phase velocity yields a TTD phase shift. Alternatively, the control voltage can be increased beyond the pull-down voltage of the MEMS bridges such that the capacitive loading greatly increases and shorts the line to ground. The measured results demonstrate 0 - 60-GHz TTD phase shifters with 2-dB loss/118 [degrees] phase shift at 60-GHz ([approximately] 4.5-ps TTD) and 1.8-dB loss/84 [degrees] phase shift at 40 GHz. Also, switches have been demonstrated with an isolation of better than 40 dB from 21 to 40 and 40 to 60 GHz. In addition, a transmission-line model has been developed, which results in very close agreement with the measured data for both the phase shifters and switches. The pull-down voltage is 10-23 V, depending on the residual stress in the MEMS bridge. To our knowledge, this paper presents the first wide-band TTD MEMS phase shifters and wide-band switches to date. Index Terms - MEMS, phase shifters, switches.

An overview of recent progress in the research and development of micromachined antennas, transmission lines, waveguides structures, and planar movable components for terahertz frequencies is presented. Micromachining is shown to provide a low-cost alternative to conventional (and very expensive) machined-waveguide technology, resulting in antennas with excellent radiation patterns, low-loss tuners, and three-dimensional (3-D) micromachined structures suitable for terahertz applications. Fabrication procedures for a variety of micromachined waveguide and planar structures are described here, along with measured terahertz performance. Applications of micromachining techniques for terahertz systems include focal-plane imaging arrays requiring a large number of elements and low-cost receivers for commercial and industrial applications such as pollution monitoring. Index Terms - MEMS, micromachining, millimeter wave, submillimeter wave, terahertz.

This paper presents the design and characterization of compact high-power RF microelectromechanical system single-pole single-throw (SPST) and single-pole four-throw (SP4T) metal-contact switches. The SPST design results in a contact force of 1.9–2.8 mN at 80–90 V distributed over eight contacts and using four independent quadrants for actuation. The SP4T is a derivative of the SPST and results in a contact force of 0.45–0.7 mN per switch at 80–90 V. S-parameter measurements show an up-state capacitance of 70 and 17 fF along with a down-state resistance of 1–2 and 2–4 \Omega using Au-to-Ru contacts for the SPST and SP4T switches, respectively. The switch pull-in and release voltages are 50 and 45 V, respectively, and the switching time is t on \sim \ 10~\mu\ s and t off \sim \ 2~\mu\ s. The SPST and SP4T are capable of handling 10 and 2 W up to 100 million cycles, and the SPST has been tested with 30 W of power up to 30 million cycles before failure (all cold switched). The application areas are in compact high-power applications such as wireless communication systems and base-stations. [ABSTRACT FROM AUTHOR]

This paper presents a tunable bandpass filter with a reconfigurable-pole response. 2-, 3-, and 4-pole states can be obtained based on employing series resonators with RF switches. The synthesis for the proposed filter is established, and the bandwidth for each pole state can be selected based on theory. The filter is built on a Duroid substrate with \varepsilon r=10.2 and h=25\ \mil. The tuning for the center frequency is done using Schottky diodes, and the selection of the filter poles is achieved using RF microelectromechanical systems switches. A tuning of 0.73–1.03 GHz is achieved with a 1-dB fractional bandwidth of 3.9%–5.2%. The rejection levels at 200-MHz offset frequency of 2-, 3-, and 4-pole states are 28, 36, and 45 dB, respectively. This filter topology can find applications in reconfigurable radios with dynamic rejection levels. [ABSTRACT FROM AUTHOR]

This paper presents a CMOS amplifier-multiplier-antenna array capable of generating an EIRP of 3–4 dBm at 420 GHz. The chip is built using a 45-nm CMOS SOI process, and efficient on-chip antennas are used to extract the power out of the chip. The design is based on a 90–110 GHz distribution network with splitters and amplifiers, and a balanced quadrupler capable of delivering up > \100~\mu\W of power at 370–430 GHz. The amplifier–multiplier concept is proven on a 2\times4 array, and it can be also scaled to any N\times M array using additional W-band splitters and amplifiers. [ABSTRACT FROM AUTHOR]

In this paper, we present 30 distinct RF MEMS capacitive switch designs that are the product of topology optimizations that control key mechanical properties such as stiffness, response to intrinsic stress gradients, and temperature sensitivity. The designs were evaluated with high-accuracy simulations prior to micro-fabrication. We built and tested more than 170 switches, including at least five per distinct design. Experimental results confirm that the finite element models are accurate and that the switches behave as intended by the different optimizations. Extensive testing results include actuation and release voltages as a function of temperature, switching times, capacitance ratios, fitted S-parameters, and profile measurements during actuation and over temperature. \hfill[2013\-0203] [ABSTRACT FROM PUBLISHER]

In this paper, a third-order tunable diplexer and a third-order tunable dual-band bandpass filter with flexible tuning capabilities and high selectivity are proposed. Both the diplexer and dual-band filter consist of two passbands that share a common resonator for size reduction. By adding tuning elements in the middle and ends of the common resonator, the resonant frequencies of the even and odd modes can be independently tuned, thus offering flexible tuning for multi-band operations. Also, by adding extra resonators next to the common resonator, high-order tunable multi-band filters can be obtained with higher stopband suppression. The 1.3–2.4-GHz tunable diplexer shows that the two channels can be either independently tuned or simultaneously tuned as desired. The two channels cover a fractional tuning range of 34% and 18.6%, respectively, while keeping high stopband suppressions, higher isolation, and good input impedance matching. Similarly, the 1.1–2.45-GHz tunable dual-band filter shows independent and simultaneous tuning capability operating with good impedance matching and high stopband suppression. [ABSTRACT FROM AUTHOR]

This paper presents the first built-in self-test system (BIST) for W-band transmit–receive phased-array modules. Low-loss high-isolation switches are attached to the RF input and output ports using \lambda/4 transmission-line sections, which result in a high shunt impedance when the BIST is disabled and minimal penalty in additional loss. A W-band in-phase/quadrature down-conversion mixer/receiver with <0.5-dB amplitude and 4^\circ–5^\circ phase imbalance at 90–100 GHz is also implemented on-chip and is used as an on-chip vector network analyzer. The BIST allows the measurement of the normalized S21 in both transmit and receive modes with high accuracy (4-bit phase response, <0.5-dB amplitude variation) at 90–100 GHz without any external calibration. The BIST also results in a normalized frequency response that agrees well with the measured S-parameters at 90–100 GHz. [ABSTRACT FROM PUBLISHER]

This paper presents a 0.32 THz 4x4 imaging array based on an advanced SiGe technology. Each pixel is composed of a high efficiency on-chip antenna meeting all metal-density rules, which is coupled to a SiGe detector and a low noise CMOS operational amplifier. A quartz superstrate is used on top of the imaging chip to improve the radiation efficiency. The array results in an average NEP of 34 pW/Hz^1/2 at an IF of 10–100 kHz for a detector bias current of 50–150 µA, a responsivity of 18 kV/W and a 3-dB bandwidth of 25 GHz. The power consumption is 2.4 mW/pixel. Extensive measurements are presented which show the challenges encountered in obtaining accurate measurements at THz frequencies using a quasi-optical set-up, and the decisions taken to quote the average NEP values. [ABSTRACT FROM PUBLISHER]

This paper presents a W-band wafer-scale phased- array transmitter with high-efficiency on-chip antennas. The 4\,\times\,4 array is based on an RF beamforming architecture with an equiphase distribution network and phased shifters placed on every element. The differential on-chip antennas are implemented using a 100 \mu\ m thick quartz superstrate and with a simulated efficiency of \sim \ 45\% at 110 GHz. The phased array is designed with low mutual coupling between the elements and results in a stable active antenna impedance versus scan angle. The phased array is built in the Jazz SBC18H3 SiGe BiCMOS process, and is 6.5\,\times \,6.0 \ mm^2. Measurements show two-dimensional pattern scanning capabilities with a directivity of 17.0 dB, an array gain of \sim \ 26.5~\ dB at 110 GHz, and an EIRP of 23–25 dBm at 108–114 GHz. The power consumption is 3.4 W from a 1.9 V supply. To our knowledge, this work represents the first W-band wafer-scale phased array to-date. The application areas are in point-to-point communication systems in the 100–120 GHz range. [ABSTRACT FROM PUBLISHER]

This paper presents a four-element X-band phased-array transmitter in \0.13-\mu\ m CMOS. The design is based on the all-RF architecture and contains a 5-bit phase shifter (lowest bit is used as a trim bit), 4-bit gain control (to reduce the rms gain error), and power amplifiers capable of delivering a PSAT of \13.5 dBm per channel at 8.5–10.5 GHz. The chip can be used in the linear mode for communication systems and in the saturated mode for frequency-modulated continuous-wave radar systems, and therefore, extensive analysis is done on the phase shifter distortion versus input power. Spectral regrowth and error vector magnitude measurements indicate that the chip can support at least 20-MSym/s quadrature phase-shift keying and binary phase-shift keying modulation at an output power of +\5 dBm per channel. Packaging techniques based on chip-on-board and quad flat no-lead (QFN) modules have been implemented with the four-channel chip, and both show a nearest neighbor coupling of -\ 30 dB at 8–10 GHz, limited by bond-wire coupling. The chip dimensions are \2.9\times \3.0 mm^2 and it consumes 870 mW from 2- and 3-V power supplies. [ABSTRACT FROM PUBLISHER]

This paper presents a 4 \times 4 transmit/receive (T/R) SiGe BiCMOS phased-array chip at 90–100 GHz with vertical and horizontal polarization capabilities, 3-bit gain control (9 dB), and 4-bit phase control. The 4 \times 4 phased array fits into a \ 1.6\times \ 1.5\ \ mm^2 grid, which is required at 94 GHz for wide scan-angle designs. The chip has simultaneous receive (Rx) beam capabilities (V and H) and this is accomplished using dual-nested 16:1 Wilkinson combiners/divider with high isolation. The phase shifter is based on a vector modulator with optimized design between circuit level and electromagnetic simulation and results in <1 dB and <\ 7.5^\circ\ \rms gain and phase error, respectively, at 85–110 GHz. The behavior of the vector modulator phase distortion versus input power level is investigated and measured, and design guidelines are given for proper operation in a transmit (Tx) chain. The V and H Rx paths result in a gain of 22 and 25 dB, respectively, a noise figure of 9–9.5 (max. gain), and 11 dB (min. gain) measured without the T/R switch, and an input P1\ {dB} of -31 to -26 dBm over the gain control range. The measured output Psat is \sim-5 dBm per channel, limited by the T/R switch loss. Measurements show \pm0.6- and \pm0.75-dB variation between the 4 \times 4 array elements in the Tx mode ( Psat) and Rx mode, respectively, and <-40-dB coupling between the different channels on the chip. The chip consumes 1100 mA from a 2-V supply in both the Tx and Rx modes. The design can be scaled to >10 000 elements using polyimide redistribution layers on top of the chip and the application areas are in W-band radars for landing systems. [ABSTRACT FROM PUBLISHER]

This paper presents a 16-element phased-array receiver for 76–84-GHz applications with built-in self-test (BIST) capabilities. The chip contains an in-phase/quadrature (I/Q) mixer suitable for automotive frequency-modulation continuous-wave radar applications, which is also used as part of the BIST system. The chip achieves 4-bit RF amplitude and phase control, an RF to IF gain of 30–35 dB at 77–84 GHz, I/Q balance of < \ 1 dB and < \10^\circ at 76–84 GHz, and a system noise figure of 18 dB. The on-chip BIST covers the 76–84-GHz range and determines, without any calibration, the amplitude and phase of each channel, a normalized frequency response, and can measure the gain control using RF gain control. System-level considerations are discussed together with extensive results showing the effectiveness of the on-chip BIST as compared with standard S-parameter measurements. [ABSTRACT FROM PUBLISHER]