Systematic Analysis of Quadrature VCO With Capacitive Source Degeneration Coupling and Spontaneous Transconductance Matching Techniques

This brief proposes a quadrature voltage-controlled oscillator (QVCO) using capacitive source degeneration coupling (CSDC) and spontaneous transconductance matching (STM) techniques. Mismatch in QVCO structure results in serious phase and gain errors. Thus, a CSDC structure is used to overcome phase error, and an STM structure is adopted to reduce gain error. Moreover, a systematic analysis of QVCO on the proposed techniques is presented to design a remarkable phase error of less than 0.1°. Measurement results reveal that the proposed QVCO has a phase error of 0.07° at 2.45 GHz. The measured phase noise is -121 dBc/Hz at 1 MHz offset and consumes 3.81 mW under a 1.8V supply voltage, which achieve a figure of merit of -182.98. The tuning range should be between 2.303 GHz and 2.475 GHz to fit the requirement of IEEE 802.15.4.