Current Reusing VCO and Divide-by-Two Frequency Divider for Quadrature LO Generation

Abstract

For low-power and accurate quadrature local oscillator (LO) signal generation, an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -tank voltage controlled oscillator (VCO) operating at double the required LO-frequency reuses the bias current of divide-by-two frequency divider. The current reusing VCO and divide-by-two frequency divider are targeted to generate the LO signals for a 1.57 GHz global positioning system receiver. Implemented in a 0.18 mum CMOS technology, the current reusing VCO and divide-by-two frequency divider consumes 1.7mA from a 1.8 V supply. The measured phase noise is -120dBc/Hz at 1 MHz offset when the carrier frequency is 1.57GHz.