A SiGe:C BiCMOS driver/balun/switch function block for a 30 GHz satcom transmit array

A custom transmitter IC for Ka band employing orthogonal polarization required the combination of balun, SPDT switch and driver amplifier. This paper describes how these functions can be merged into one highly compact, Gilbert cell derived circuit. It achieves a small signal gain better than 15 dB in the 27 to 30GHz frequency range together with an isolation of up to 20 dB. It consumes 96.1mW from a 3.3V supply and has an input referred 1 dB compression point of -17 dBm. Occupying an area of only 0.25mm
²
, the circuit is well suited for transmitter architectures in dense phased array systems operating at Ka band.