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

Abstract

An amplifier topology based on a transformercoupled cascode stage is presented and compared with the most used solutions for sub-lm 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-lm CMOS technologies and mm-wave operation.

A Comparative Analysis between Standard and mm-Wave Optimized BEOL in a Nanoscale CMOS Technology

“…This approach is motivated by the considerations discussed below. Integrated transformers are very important passive components, especially at mm-wave frequencies, since they are extensively adopted to implement several crucial functions, such as single-ended-to-differential and differential-to-single-ended conversions along with electrostatic discharge (ESD) protection at input/output antenna interfaces [13][14][15][16][17], resonant load in RF/mm-wave amplification stages [18,19], LC tank in oscillators [20][21][22], power combining [23,24], etc. Moreover, differently from simple spiral inductors that can highly benefit from top thick metal along with multi-layer structures and maximum oxide thickness to outdistance from the substrate, integrated transformer configurations provide more complete information on the BEOL, since they also include the effects of lower metals and intermetal oxide thickness.…”