A 1GHz Single Chip Quadrature Modulator without External Trimming

A monolithic quadrature modulator is presented, using a new approach for realising on chip the 90 degree phase shifter. 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 5 V power supply.