A passive transmission line phase shifter (TLPS) with lumped elements is implemented in a commercial 0.18 mum BiCMOS process. The phase shifter consumes no DC power, requires only one control voltage and has a size of only 1.3times0.8 mm 2 while offering a continuously adjustable phase shift of over 360deg. At 5.2 GHz and for 360deg phase control, the measured insertion loss amounts (7.3plusmn2) dB. To the knowledge of the authors, the circuit has the lowest insertion loss reported to date for a passive phase shifter integrated in silicon with 360deg phase control. The circuit is well suited for adaptive antenna combining in mobile receivers.