This paper presents and analyses a phase shifter for diversity receivers, which modulates the I-/Q-vector in the constellation diagram. The system consists of a three stage programmable gain amplifier (PGA) chain in both branches. The design covers the full phase range of 360 degrees. Each stage can be programmed to amplify the incoming signal between 19 dB and 63 dB with a centre frequency of 3 MHz. The radio frequency (RF) signal is down-converted to an intermediate frequency (IF) of 5 MHz, where phase shifting is done. The circuit is intended for an automotive satellite radio receiver in Sand L-band. Thus, demand automotive requirements have to be fulfilled. The supply voltage is 1.8V. Compared to other phase shifters, the power consumption of 2.7 mW is highly energy-efficient. This system includes a constant gm-source and a biasing circuit. All requirements are verified in post-layout Corner and Monte-Carlo analysis using Virtuoso and WiCkeD. The design only takes 0.116 mm(2) of silicon area in a 150-nm CMOS technology.