IEEE Journal of Solid-State Circuits vol:27 issue:8 pages:1194-1197
A monolithic quadrature modulator is presented, using a new approach for realizing a 90-degrees phase shifter on chip. This phase-shifting network does not need any phase adjusting to achieve the phase error specification of 3-degrees over a frequency range from 800 MHz to 1 GHz. The quadrature modulator is integrated in a 9-GHz SI bipolar process. Measurements show an image rejection of over 32 dB for the considered frequency range, consuming 24 mA from a +2.5/-2.5-V power supply.