SiGe transformer matched power amplifier for operation at millimeter-wave frequencies

In this paper, a transformer matched power amplifier for operation at millimeter-wave frequencies is presented. The SiGe single-stage push-pull amplifier uses a stacked transformer above a ground shield for output matching. The millimeter-wave transformer has a high coupling factor k = 0.8 and provides a very compact circuit layout. At 61.5 GHz the class-AB biased amplifier achieves a power gain of 12 dB with 8.5 dBm output power at a 1 dB compression. The saturated output power was measured up to P/sub sat/ = 14 dBm with a maximum PAE of 4.2%.