An X-Band Superharmonic Injection-Coupled Quadrature VCO (IC-QVCO) with a Tunable Tail Filter for I/Q Phase Calibration

Abstract

A superharmonic injection-coupled quadrature oscillator topology ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IC-QVCO</i> ) for low power low phase noise quadrature signal synthesis is introduced. A tunable tail filter ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TTF</i> ) reduces the oscillator phase noise and calibrates the residual quadrature error in the presence of a 3-σ variation in the device parameters. As a proof of concept, a 9 GHz prototype is implemented in a 0.18 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m RF CMOS process, and achieves a measured phase noise figure of merit (FoM) ranging from 177.3 to 182.6 dBc/Hz along the 9.0 to 9.6 GHz frequency tuning range while draining only 5 mA from a 1.8 V power supply. Phase error tuning up to ±11° is demonstrated using time domain measurements. In comparison, an identical <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IC-QVCO</i> without the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TTF</i> was measured to have 1-4 dB worse phase noise performance across the tuning bandwidth.