Tamer Ali

A 3.8 mW/Gbps Quad-Channel 8.5–13 Gbps Serial Link With a 5 Tap DFE and a 4 Tap Transmit FFE in 28 nm CMOS

This paper presents a quad-lane serial transceiver that supports virtually all data center communication standards around 8.5-13 Gbps, implemented in 28 nm CMOS technology. The transmitter consists of 20:2 mux followed by a half-rate source-series terminated (SST) driver embedded with a 4 tap FFE and an analog equalizer. The receiver has an adaptive CTLE, 5 tap DFE, and fully digital CDR followed by 2:20 demux. At 13 Gbps, the transceiver can equalize 35 dB Nyquist loss at BER of 10-12. At 1.0 V supply, the transceiver consumes 49 mW/lane at 13 Gbps rate with full equalization capability. An LC VCO-based fractional PLL provides the clocking to quad TX/RX lanes using a low-power inductively tuned clock routing channel. The transceiver architecture not only enables the baud rate operation from 8.5 to 13 Gbps but also supports a wide range of oversampled subrates. This work represents the lowest reported power in its class to date, and the transceiver is suitable for many applications due to its comprehensive flexibility and power efficiency.

A Sub-200 fs RMS jitter capacitor multiplier loop filter-based PLL in 28 nm CMOS for high-speed serial communication applications

An 8.0 GHz to 12.2 GHz PLL with a capacitor multiplier-based active loop filter is designed in a 28 nm digital CMOS process. A passive loop filter-based version of the PLL is also implemented for comparison. While the PLL area is comparable to that of digital PLLs, the PLL performance is as good as that of an analog PLL that employs a passive loop filter. The capacitor multiplier-based active loop filter PLL has a jitter performance of 198 fs (rms), while its passive loop filter-based counterpart shows a jitter performance of 195 fs (rms). The PLL occupies 0.093 mm2 and consumes 15.5 mA at 1.0V.

A Dual-Channel 23-Gbps CMOS Transmitter/Receiver Chipset for 40-Gbps RZ-DQPSK and CS-RZ-DQPSK Optical Transmission

This paper describes a dual-channel 23 (20 to 27) Gbps chipset designed in a 40-nm CMOS process for 40 Gbps differential quadrature phase-shift keying (DQPSK) optical transmission. The transmitter has a 2-tap FIR filter and generates two channels of full-rate data. Data outputs exhibit 10 ps rise/fall times, 0.2 psrms RJ, 0.8 pspp DJ, and a ±0.5 UI skew adjustment relative to the full-rate and half-rate clock outputs. The receiver has two 20-27-Gbps input channels, with each channel including a peaking filter, decision threshold adjustment, and 1-tap loop-unrolled DFE. It achieves a 7- mVppd input sensitivity and a 0.7-UIpp high-frequency jitter tolerance. The transmitter and receiver dissipate 0.63 and 1.2 W, respectively.

A dual 23Gb/s CMOS transmitter/receiver chipset for 40Gb/s RZ-DQPSK and CS-RZ-DQPSK optical transmission

This paper presents the first CMOS dual bitrate chipset with equalization in transmitter and receiver as well as a clock to data skew adjustment. Both the transmitter and the receiver consume less power than those in previously published results in the works of Hosida et al. (2007).

A 3.8 mW/Gbps quad-channel 8.5–13 Gbps serial link with a 5-tap DFE and a 4-tap transmit FFE in 28 nm CMOS

This paper presents a quad-lane serial link that supports virtually all data center system-side and line-side communications standards from 8.5-13 Gbps, implemented in 28 nm CMOS. The Tx is series source terminated with a 4-tap FFE. Its swing ranges from 33 mV to 1 Vppd. The Rx has CTLE, 5-tap DFE and CDR with 2x-oversampling, and baud-rate timing recovery options. At 13 Gbps, the link can equalize 35 dB loss at Nyquist frequency with BER of 10-12. The link consumes 49 mW per lane at 13 Gbps. This is the lowest reported power in its class to date, and with comprehensive programmability for a wide range of standards.

29.2 A transmitter and receiver for 100Gb/s coherent networks with integrated 4×64GS/s 8b ADCs and DACs in 20nm CMOS

At rates of 100Gb/s and above, CMOS DSP-based transceivers integrated with high-sampling-rate data converters are critical to realize the phase-sensitive modulation schemes based on coherent detection that are essential to metro and long-haul networks [1]. To support dual-polarization QPSK format, quad low-power DACs and ADCs are needed and precise phase alignment has to be maintained between XI, XQ, YI, and YQ channels, in order to transmit and extract the phase information in the coherent system, as shown in Fig. 29.2.1. For long-haul transmission at 100Gb/s, because of the FEC overhead, the baud rate per channel can be as high as 32Gb/s. In addition, the receiver often requires double sampling at 64GS/s for robust clock-data recovery and SNR improvement for stressed channels. Double sampling also enables the DSP to implement more complicated equalization schemes and more flexible spectrum engineering at high frequency on the transmitter side. This paper reports the receiver and transmitter fully integrated in a 100G coherent DSP chip, using 4×64GS/s ADCs and DACs with 8b resolution, fabricated in a standard 20nm CMOS process.

A 23mW/lane 1.2–6.8Gb/s multi-standard transceiver in 28nm CMOS

This paper describes the design of a low power multi-standard transceiver in 28nm CMOS technology. Using novel circuit techniques and implementation features, the transceiver can operate at data rates of 1.2-6.8Gb/s while supporting a wide range of communication standards, including SGMII, QSGMII, PCIE, SATA, USB3, XAUI and RXAUI. Power consumption per lane is 23mW at 0.9V for SATA3 at 6Gb/s, with an area of 0.265mm2 for a single-lane transceiver with PLL.