A fully integrated single-channel transmitter is proposed for 30/35 GHz dual-band operation for communication/radar phased array systems. Implemented in a 0.25 μm BiCMOS technology, the transmitter achieves 10° phase shift resolution and 5 bit amplitude resolution suitable for advanced beamforming algorithms for suppression and nulling of side lobes. The integration covers from the baseband I/Q modulation to the RF output, including a low phase noise on-chip VCO and dual-band LO generation circuitry. An RF output power of > +14.5 dBm is achieved in both frequency bands by a linear power amplifier. The core circuit occupies a die area of 1.1 mm 2 and consumes 222-241 mA current from a 3.3 V supply.