Single and Power-Combined Linear E-Band Power Amplifiers in 0.12-μ m SiGe With 19-dBm Average Power 1-GBaud 64-QAM Modulated Waveforms

This paper presents a set of wideband, fully integrated E-band power amplifiers (PAs) designed in 0.12-μm silicon-germanium (SiGe) BiCMOS and working in the range of 60-75 GHz. The single PA is based on common-emitter (CE) driver stages followed by a CE output stage. A three-stage and four-stage versions of the single-PA as well as fourand eight-way combined variants of the four-stage PA are measured and compared. The single, four-way, and eight-way combined PAs achieve saturated output powers of 16, 19.5, and 24 dBm with peak power-added efficiencies (PAEs) of 18%, 11%, and 12%, respectively. Modulated waveforms are passed through each amplifier and data rates as high as 32 Gb/s are demonstrated for all amplifiers when driven in the linear mode. Measurements of how error-vector magnitude (EVM) and PAE degrade versus output power are presented and it is demonstrated that the eight-way combined PA can deliver 17-20 dBm of average power in a 64-quadratic-amplitude modulation, 1-Gbaud waveform (6 Gb/s), with an EVM of -32 to -24 dB and a PAE of 3%-5% without predistortion. To the author's knowledge, this is the first paper reporting detailed measurements of PA EVM and PAE versus output power at these frequencies.