Design of power-efficient CMOS based oscillator circuit with varactor tuning control

This paper presents a low-power, wide tuning range CMOS voltage-controlled oscillator with MCML (MOS current mode logic) differential delay cell. Voltage controlled oscillator (VCO) circuit is designed in TSMC 0.25 μm CMOS process. To achieve the broad frequency range concept of variable capacitance is employed in the proposed VCO circuit. Source/drain tuning voltage (Vtune) and body bias voltage (Vb) of I-MOS varactor are used to achieve variable capacitance at different I-MOS varactor widths (W). The dual control voltage of I-MOS varactor results in a tuning range from 0.528 GHz to 2.014 GHz. VCO's figure of merit (FoM) is 152.13 dBc/Hz with phase noise of −93.77 dBc/Hz at 1 MHz offset from the oscillation frequency. The proposed VCO dissipates maximum power of 3.127 mW.

РАЗРАБОТКА SPICE-МОДЕЛИ МДП-ВАРАКТОРА

Разработана эквивалентная схема, методика экстракции SPICE-параметров МДП-варактора на основе результатов проведенных измерений специальных тестовых структур в составе пластин, модель верифицирована, сформирован модуль, учитывающий статистический разброс значений параметров процесса технологического производства. An appropriate equivalent circuit of MOS-varactor has been developed, as well as a technique for extracting its SPICE-parameters, based on the results of test structures measurements. The model has been verified, a statistical module has been created that takes into account the fabrication process parameters variation.

A CMOS W-Band Amplifier with Tunable Neutralization Using a Cross-Coupled MOS–varactor Pair

This paper presents a CMOS W-band amplifier adopting a novel neutralization technique for high gain and stability. The W-band amplifier consists of four common-source differential gain cells that are neutralized by a cross-coupled MOS–varactor pair. Contrary to conventional neutralizations, the proposed technique enables tunable neutralization, so that the gate-to-drain capacitance of transistors is accurately tracked and neutralized as the varactor voltage is adjusted. This makes the neutralization tolerant of capacitance change caused by process–voltage–temperature (PVT) variation or transistor model inaccuracy, which commonly occurs at mm-wave frequencies. The proposed tunable neutralization is experimentally confirmed by measuring gain and stability of the W-band amplifier fabricated in a 65-nm CMOS process. The amplifier achieves a measured gain of 17.5 dB at 79 GHz and a 3-dB bandwidth from 77.5 to 84 GHz without any stability issue. The DC power consumption is 56.7 mW and the chip area is 0.85 mm2.