Stacked Common-Base vs Common-Emitter mmWave PA Cells and 68-105 GHz Broadband Asymmetrical PA in 250nm InP HBT

Zheng Liu, Tushar Sharma, Kaushik Sengupta

Research output: Contribution to journalArticlepeer-review


In this paper, we perform a comparative analysis between stacked common-emitter (SCE) and stacked common-base topologies (SCB) for high efficiency and broadband millimeter-Wave (mmWave) power amplifiers (PAs) in 250 nm InP-based heterojunction bipolar transistor (HBT) technology. We propose an analytical approach to design stacked PA cells accounting for complex load impedance and intra-matching between stacked transistors to allow optimal loadpull operation of both the devices in the stack. We demonstrate how SCB cell can allow higher gain, mitigated power and efficiency trade-off and linearity, when compared to more well-established SCE cells at higher mmWave frequencies. The designed SCB and SCE cells achieve a measured gain of 11.8 dB/6dB gain, 33%/34% peak PAE, 16.8%/14.5% PAE at 6-dB back-off, and Psat of 18.7 dBm/19.6 dBm at 90 GHz. The SCB PA demonstrates superior linearity, and achieves an EVM of 2.38% at 11.8-dBm average power supporting 3 Gbps 64-QAM. The SCB PA achieves 17.9-18.9-dBm Psat across 80-110 GHz and is one of the highest efficiency, broadband and linear PAs in W-band using InP technology. Utilizing the PA cells, we demonstrate an asymmetrical broadband power combining circuit for high efficiency combining across a large relatively bandwidth. The PA operates across a 68-105 GHz P sat,3dB bandwidth with 21.5 dBm peak saturation power and 24% peak PAE.

Original languageEnglish (US)
Pages (from-to)14487-14499
Number of pages13
JournalIEEE Access
StatePublished - 2023
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Computer Science
  • General Materials Science
  • General Engineering


  • Asymmetrical combiner
  • InP HBT
  • broadband
  • common-base
  • millimeter-Wave (mmWave)
  • power amplifiers (PAs)
  • stacked PA


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