Browsing by Author "Du, Jieqiong"

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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
(2017-04-01)
Du, Yuan
;
Cho, Wei-Han
;
Huang, Po-Tsang
;
Li, Yilei
;
Wong, Chien-Heng
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 mm(2) 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 mu W/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.
A 16Gb/s 14.7mW Tri-Band Cognitive Serial Link Transmitter with Forwarded Clock to Enable PAM-16 / 256-QAM and Channel Response Detection in 28 nm CMOS
(2016)
Du, Yuan
;
Cho, Wei-Han
;
Li, Yilei
;
Wong, Chien-Heng
;
Du, Jieqiong
A cognitive tri-band transmitter with forwarded clock using multi-band signaling and high-level digital signal modulations is presented for serial link application. The transmitter features learning an arbitrary channel response by sending a sweep of continuous wave, detecting power level, and accordingly adapts modulation scheme, data bandwidth and carrier frequency. The modulation scheme ranges from NRZ/QPSK to PAM-16/256-QAM. The highly re-configurable transmitter is capable of dealing with low-cost serial link cables/connectors or multi-drop buses with deep and narrow notches in frequency domain (e.g. 40dB loss at notches). The adaptive multi-band scheme mitigates equalization requirement and enhances the energy efficiency by avoiding frequency notches and utilizing the maximum available signal-to-noise ratio and channel bandwidth. The implemented transmitter consumes 14.7mW power and occupies 0.016mm(2) in 28nm CMOS. It achieves a maximum data rate of 16Gb/s per differential pair and the most energy-efficient FoM (defined in Fig. 8) of 20.4 mu W/Gb/s/dB considering channel condition.
A 2-GS/s 8-Bit ADC Featuring Virtual-Ground Sampling Interleaved Architecture in 28-nm CMOS
(2018-11-01)
Wang, X. Shawn
;
Jin, Xin
;
Du, Jieqiong
;
Li, Yilei
;
Du, Yuan
This brief presents a two-way time-interleaved twostep pipelined analog-to-digital converter (ADC) architecture built upon a new concept of virtual-ground sampling, featuring merged front-end track-and-hold, residue generation, input termination, and buffering. This architecture is investigated to alleviate the front-end performance tradeoff among the total-harmonic- distortion, bandwidth, and sampling rate (interleaving factor). A 2-GS/s 8b ADC using the new architecture was designed and fabricated in 28-nm CMOS, achieving 43-dB SNDR and 55-dB SFDR up to Nyquist frequency.
A 38mW 40Gb/s 4-Lane Tri-Band PAM-4 / 16-QAM Transceiver in 28nm CMOS for High-Speed Memory Interface
(2016)
Cho, Wei-Han
;
Li, Yilei
;
Du, Yuan
;
Wong, Chien-Heng
;
Du, Jieqiong
A 7.5-mW 10-Gb/s 16-QAM Wireline Transceiver with Carrier Synchronization and Threshold Calibration for Mobile Inter-chip Communications in 16-nm FinFET
(2019-01-01)
Du, Jieqiong
;
Wong, Chien-Heng
;
Tu, Yo-Hao
;
Cho, Wei-Han
;
Li, Yilei
A compact energy-efficient 16-QAM wireline transceiver with carrier synchronization and threshold calibration is proposed to leverage high-density fine-pitch interconnects. Utilizing frequency-division multiplexing, the transceiver transfers four-bit data through one RF band to reduce inter-symbol interferences. A forwarded clock is also transmitted through the same interconnect with the data simultaneously to enable low-power PVT-insensitive symbol clock recovery. A carrier synchronization algorithm is proposed to overcome nontrivial current and phase mismatches by including DC offset calibration and dedicated I/Q phase adjustments. Along with this carrier synchronization, a threshold calibration process is used for the transceiver to tolerate channel and circuit variations. The transceiver implemented in 16-nm FinFET occupies only 0.006-mm(2) and achieves 10 Gb/s with 0.75-pJ/bit efficiency and <2.5-ns latency.
An 8.8-GS/s 8b Time-Interleaved SAR ADC with 50-dB SFDR Using Complementary Dual-Loop-Assisted Buffers in 28nm CMOS
(2018-01-01)
Wang, X. Shawn
;
Chan, Chi-Hang
;
Du, Jieqiong
;
Wong, Chien-Heng
;
Li, Yilei
This paper presents an 8.8 GS/s 16-way time-interleaved asynchronous SAR ADC fabricated in 28-nm CMOS technology. A two-level 2x8 master-slave hierarchical interleaved architecture is employed. A complementary dual-loop-assisted buffer is proposed to achieve both high linearity and bandwidth with low power. This time-interleaved ADC achieves 38.4-dB SNDR and 50-dB SFDR with a Nyquist input at 8.8 GS/s sampling rate and consumes 83.4 mW, resulting in a 140 fJ/conv.-step Walden FOM with buffers.
An Analog Neural Network Computing Engine Using CMOS-Compatible Charge-Trap-Transistor (CTT)
(2019-10-01)
Du, Yuan
;
Du, Li
;
Gu, Xuefeng
;
Du, Jieqiong
;
Wang, X. Shawn
An analog neural network computing engine based on CMOS-compatible charge-trap transistor (CTT) is proposed in this paper. CTT devices are used as analog multipliers. Compared to digital multipliers, CTT-based analog multiplier shows significant area and power reduction. The proposed computing engine is composed of a scalable CTT multiplier array and energy efficient analog-digital interfaces. By implementing the sequential analog fabric, the engine's mixed-signal interfaces are simplified and hardware overhead remains constant regardless of the size of the array. A proof-of-concept 784 by 784 CTT computing engine is implemented using TSMC 28-nm CMOS technology and occupies 0.68 mm(2). The simulated performance achieves 76.8 TOPS (8-bit) with 500 MHz clock frequency and consumes 14.8 mW. As an example, we utilize this computing engine to address a classic pattern recognition problem-classifying handwritten digits on MNIST database and obtained a performance comparable to state-of-the-art fully connected neural networks using 8-bit fixed-point resolution.