A 16-Gb/s 14.7-mW Tri-Band Cognitive Serial Link Transmitter with Forwarded Clock to Enable PAM-16/256-QAM and Channel Response Detection

Yuan Du, Wei Han Cho, Po-Tsang Huang, Yilei Li, Chien Heng Wong, Jieqiong Du, Yanghyo Kim, Boyu Hu, Li Du, Chunchen Liu, Sheau Jiung Lee, Mau-Chung Chang

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


A cognitive tri-band transmitter (TX) with a forwarded clock using multiband signaling and high-order digital signal modulations is presented for serial link applications. The TX features learning an arbitrary channel response by sending a sweep of continuous wave, detecting power level at the receiver side, and then adapting modulation scheme, data bandwidth, and carrier frequencies accordingly based on detected channel information. The supported modulation scheme ranges from nonreturn to zero/Quadrature phase shift keying (QPSK) to Pulse-amplitude modulation (PAM) 16/256-Quadrature amplitude modulation(QAM). The proposed highly reconfigurable TX is capable of dealing with low-cost serial channels, such as low-cost connectors, cables, or multidrop buses with deep and narrow notches in the frequency domain (e.g., a 40-dB loss at notches). The adaptive multiband scheme mitigates equalization requirements and enhances the energy efficiency by avoiding frequency notches and utilizing the maximum available signal-to-noise ratio and channel bandwidth. The implemented TX prototype consumes a 14.7-mW power and occupies 0.016 mm2 in a 28-nm CMOS. It achieves a maximum data rate of 16 Gb/s with forwarded clock through one differential pair and the most energy efficient figure of merit of 20.4 μW/Gb/s/dB, which is calculated based on power consumption of transmitting per gigabits per second data and simultaneously overcoming per decibel worst case channel loss within the Nyquist frequency.

Original languageEnglish
Article number7765148
Pages (from-to)1111-1122
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Issue number4
StatePublished - 1 Apr 2017


  • Cognitive
  • continuous-time linear equalization (CTLE)
  • decision feedback equalization (DFE)
  • digital modulation
  • energy efficiency
  • feedforward equalization (FFE)
  • forwarded clock
  • Inter-Symbol Interference (ISI)
  • memory interface
  • multiband signaling
  • multidrop bus (MDB)
  • multilevel signaling
  • nonreturn to zero (NRZ)
  • pulse-amplitude modulation (PAM)
  • quadrature amplitude modulation (QAM)
  • serial link
  • source synchronous
  • transmitter (TX)
  • uW/Gb/s/dB
  • wireline

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