Transformer-coupled cascode stage for mm-wave power amplifiers in sub-μm CMOS technology

An amplifier topology based on a transformer-coupled cascode stage is presented and compared with the most used solutions for sub-mu m CMOS power amplifiers, which are the common-source stage, cascode stage, and capacitive-coupled cascode stage. The comparison was carried out by designing each amplifier in a 65-nm CMOS technology and for a 60-GHz operating frequency. The design was optimized for a trade off among power gain, saturated output power, and linearity. Operating from a 1.2-V supply voltage, the proposed amplifier improves both small-signal and large-signal performance with respect to the most common approaches, thus demonstrating effectiveness with sub-mu m CMOS technologies and mm-wave operation.