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Open Access Publications from the University of California

New Circuit Techniques Enabling Millimeter-Wave and Terahertz Transceivers in Nanoscale Silicon

  • Author(s): Wang, Zheng
  • Advisor(s): Heydari, Payam
  • et al.

The vastly under-utilized spectrum in the sub-THz frequency range enables disruptive applications including 10Gb/s chip-to-chip wireless communications and imaging/spectroscopy. Owing to aggressive scaling in feature size and device fT/fmax, nanoscale CMOS technology potentially enables integration of sophisticated systems at this frequency range. This dissertation mainly focuses on the design of a 210GHz fundamental transceiver and also covers the design of a W-band fully integrated imaging system utilizing a novel concept of spatial-overlapping super pixels.

Firstly, a 210GHz transceiver with OOK modulation in a 32nm SOI CMOS process (fT/fmax=250/320GHz) is presented. The transmitter (TX) employs a 2×2 spatial combining array consisting of a double-stacked cross-coupled voltage controlled oscillator (VCO) at 210GHz with an on-off-keying (OOK) modulator, a power amplifier (PA) driver, a novel balun-based differential power distribution network, four PAs and an on-chip 2×2 dipole antenna array. The non-coherent receiver (RX) utilizes a direct detection architecture consisting of an on-chip antenna, a low noise amplifier (LNA), and a power detector. The VCO generates measured -13.5dBm output power; and the PA shows a measured 15dB gain and 4.6dBm Psat. The LNA exhibits a measured in-band gain of 18dB and minimum in-band noise figure (NF) of 11dB. The TX achieves an EIRP of 5.13dBm at 10dB back-off from saturated power. It achieves an estimated EIRP of 15.2dBm when the PAs are fully driven. This is the first demonstration of a fundamental frequency CMOS transceiver at the 200GHz frequency range.

Secondly, a W-band direct-detection-based receiver array in an advanced 0.18µm BiCMOS process is presented, which incorporates a new concept of spatial-overlapping super-pixels for millimeter-wave imaging applications. The use of spatial-overlapping super-pixels results in (1) improved SNR at the pixel level through a reduction of spillover losses, (2) partially correlated adjacent super-pixels, (3) a 2×2 window averaging function in the RF domain, (4) the ability to compensate for the systematic phase delay and amplitude variations due to the off-focal-point effect for antennas away from the focal point, and (5) the ability to compensate for mutual coupling effects among the array elements. The receiver chip achieves a measured peak coherent responsivity of 1,150MV/W, an incoherent responsivity of 1,000MV/W, a minimum noise-equivalent power (NEP) of 0.28fW/Hz^1/2 and a front-end 3-dB bandwidth from 87-108GHz, while consuming 225mW per receiver element. The measured noise-equivalent temperature difference (NETD) of the SiGe receiver chip is 0.45K with a 20ms integration time.

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