A low local input power 1.9 GHz Si-bipolar quadrature modulator without any adjustment

A 1.9 GHz quadrature modulator with on-chip 90/spl deg/ phase-shifter was fabricated in a silicon bipolar technology. An image-rejection ratio over 45 dB and a carrier feed-through below -40 dBc were attained at -15 dBm local input power from 2.7 V supply. A die size of quadrature modulator IC is 2.49 mm/spl times/2.14 mm.