A 0.5–20GHz quadrature downconverter

A quadrature downconverter with 4 GHz IF bandwidth and working over the 0.5-20 GHz RF frequency range has been designed, fabricated, and tested. The downconverter uses a frequency doubling and dividing scheme to generate quadrature local oscillator signals from 0.5-17 GHz and a pair of Gilbert-cell mixers to perform downconversion. When the IF outputs are combined with a commercial quadrature hybrid, the mixer achieves an image rejection ratio greater than 35 dB over the entire band with no on-chip calibration or tuning. The active die area is approximately 0.5times1 mm².