Horizontal Current Bipolar Transistor (HCBT) Technology for High Linearity RF Mixers

The high linearity downconversion active mixers are demonstrated in the horizontal current bipolar transistor (HCBT) technology. The HCBTs fabricated by uniform n-collector doping profile, long hydrofluoric (HF) etching, and long tetramethylammonium hydroxide (TMAH) etching are shown to be optimal for mixer performance. The circuits fabricated with the optimum HCBTs in 180-nm bipolar complementary metal-oxide semiconductor (BiCMOS) process are packaged and measured, resulting in the best HCBT mixer characteristics published so far. The HCBT mixer uses a double-balanced Gilbert cell core with an integrated local oscillator (LO) buffer driver and employs an open-collector output topology. It provides broadband operation and frequency downconversion, measured up to 3 GHz, with a maximum power consumption of 550 mW at the peak linearity performance. The measured peak input third-order intercept point (IIP3) and conversion gain (CG) of 30.3 dBm and 6.0 dB, respectively (at 900-MHz input), are suitable for the base station transceivers and wireless infrastructure. The HCBT technology represents a low-cost BiCMOS platform capable of meeting the various requirements in the fabrication of the radio frequency integrated circuits (RFICs).