An integrated 100 MHz to 1 GHz I/Q modulator with CML phase shifter

Abstract

A direct I/Q modulator suitable for operation at output frequencies from 100 MHz to 1 GHz and baseband frequencies from 60 to 500 kHz is fabricated in a 0.8 /spl mu/m BiCMOS process. The modulator uses a phase shifter topology based on digital CML latches. The circuit operates from a single 5 V supply and it consumes about 100 mA. The circuit size is 2.0 mm/spl times/2.0 mm and it is packed in a 28 pin SOIC. According to measurements, the output power is -11/spl plusmn/0.5 dBm at 100 MHz and -15/spl plusmn/ 2.25 dBm at 950 MHz over the temperature range of -10 to +85/spl deg/C. LO suppression is roughly 38 dBc and image rejection 41 dBc.