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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.

This brief presents a nano-ampere CMOS current reference (CCR) for low power application with a wide temperature range from −40°C to 120°C. The current reference is generated by the division of a temperature-independent voltage and resistance in a simple way. The low temperature-independent voltage is generated based on the threshold voltage difference between two same-type NMOS transistors with different channel lengths working in the subthreshold region, while the temperature-independent resistance is made up by two poly resistors, whose temperature coefficients are opposite. By designing a low voltage to allow for a small resistance, the CCR circuit takes a small chip area while generating nano-ampere current. The proposed CCR circuit was implemented in a standard 0.18- ${\mu }\text{m}$ CMOS process and its active area is 0.054 mm2. Among the measured 10 samples, the average output current is 11.6 nA and the average temperature coefficient is 169 ppm/°C.

This letter presents a wideband transformer balun with a center open stub. Since the interconnected line between two coupled-lines greatly deteriorates the performance of balun in millimeter-wave designs, the proposed center open stub provides a good solution to further optimize the balance of balun. The proposed transformer balun with center open stub has been fabricated in 90 nm CMOS technology, with a compact chip area of 0.012 mm 2 . The balun achieves an amplitude imbalance of less than 1 dB for a frequency band ranging from 1 to 48 GHz along with a phase imbalance of less than 5 degrees for the frequency band ranging from 2 to 47 GHz.

An ultra-low-power common-gate low noise amplifier (CG-LNA) for 2.4 GHz wireless sensor network (WSN) applications is proposed in this letter. The current-reuse and active $g_{\rm m}$ -boosting techniques are utilized. The analysis, design method and measurement results are shown. An implemented prototype using 0.18 $\mu$ m CMOS technology is evaluated using on-wafer probing. Measurements also show a gain of 14.7 dB and an ${\rm IIP}_{3}$ of 2 dBm at 2.44 GHz. The measured noise figure is 4.8 dB at 2.44 GHz. ${\rm S}_{11}$ is below ${-}18$ dB from 2–3 GHz. The proposed LNA consumes 0.58 mW from 1.8 V dc supply.

This paper presents two new strain gauge bridge-to-pulse position modulation (PPM) converters. They have been developed in 2-/spl mu/m BiCMOS technology. The first one uses a chopper amplifier and a voltage-to-time converter associated in a feedback loop. This topology mainly exhibits an automatic offset cancellation capability, a ratiometric transfer function, and 10-b accuracy. The second one is a voltage-to-frequency converter using the switched-capacitor (SC) technique. It is an optimized version in terms of size minimization and noise rejection. Furthermore, a special RF transmitter has been designed in order to send the data from an intracorporal sensing and conditioning circuitry to an external computer dedicated to data analysis. Moreover, these converters are insensitive to offset drifts and are well suited for long term monitoring of orthopedic implants used for the treatment of bone fractures.