A low phase noise quadrature VCO using superharmonic injection, current reuse, and negative resistance techniques in CMOS technology

摘要

In this article, a low phase noise quadrature VCO (QVCO) is proposed, which uses superharmonic injection and current reuse techniques to reduce phase-noise and power consumption. The LC tank circuit quality factor is improved, using a negative resistance. PMOS transistors have also been used instead of NMOS transistors. As a result of these modifications, further phase noise reduction is achieved. The QVCO consists of a VCO operating at 2(0) (twice the operating frequency) injecting its output signal into the common source nodes of two other oscillators operating at (0). Using this superharmonic injection technique, in addition to phase noise reduction, the chance of injection pulling caused by powerful PA signals is reduced. Also, the current reuse technique automatically adapts its voltage to the requirement of the supplied stages, therefore, it is not limiting the VCO output swing. Designed for the 900MHz band and simulated in a 0.18 mu m CMOS technology with 1.8V power supply, the circuit achieves a phase noise of -141.5dBc/Hz at 1MHz offset frequency, while consuming 12.8mW power. The proposed circuit is compared with several re-simulated previously published work. The comparison shows 17.5dB reduction in phase noise compared to conventional P-QVCO, while consuming the same amount of power.