A 2.7-V monolithic SiGe HBT variable gain amplifier for CDMA applications

Abstract

A monolithic SiGe HBT variable gain amplifier with high dB-linear gain control and high linearity has been developed for CDMA applications. The VGA achieves a dynamic gain control range of 30 dB with 2.7-Vdc control-voltage range in 824-849 MHz. The maximum gain and attenuation at a center frequency of 835 MHz are 23 dB and 7 dB, respectively. Input/output VSWR keep low and constant despite change in the gain-control voltage. At a low operation voltage of 2.7 V the VGA produces a output power of 5 dBm with 20 dB power gain and -57 dBc ACPR at /spl plusmn/885 KHz offset bands.