A 28-GHz Harmonic-Tuned Power Amplifier in 130-nm SiGe BiCMOS

The design methodology and measurement results of a millimeter-wave harmonic-tuned power amplifier (PA) are presented. The PA uses optimum fundamental and second-harmonic terminations to achieve high peak power-added efficiency (PAE). We present a parasitic-aware design technique for the output network realized as a bandpass filter cascaded with or surrounded by a low-pass matching network. This technique demonstrates a method of manipulating the second-harmonic phase of a Chebyshev bandpass filter, while maintaining a suitable impedance match at the fundamental. The technique is applied to a 28-GHz PA in SiGe BiCMOS, which achieves 15.3-dB gain, 18.6-dBm saturated output power, 15.5-dBm output 1-dB compression point, and 35.3% peak PAE. When backed off 6- from 1-dB compression, the PA achieves 11.5% PAE with a third-order intermodulation product of -33.7 dBc.