Burak Catli

A Sub-2 W 39.8–44.6 Gb/s Transmitter and Receiver Chipset With SFI-5.2 Interface in 40 nm CMOS

The introduction of 40Gb/s networks, spurred by 40Gb/s WDM growth, can alleviate bandwidth bottlenecks of Internet infrastructure while simultaneously reducing operating costs. Increasingly, standard CMOS technology is used to enable transceiver speeds [1-5] previously achievable only by using expensive bipolar technology. However, at 40Gb/s, limited channel bandwidth coupled with stringent receiver jitter tolerance requirements demands better solutions than exist currently.

3.2 A 320mW 32Gb/s 8b ADC-based PAM-4 analog front-end with programmable gain control and analog peaking in 28nm CMOS

Multilevel modulation formats, such as PAM-4, have been introduced in recent years for next generation wireline communication systems for more efficient use of the available link bandwidth. High-speed ADCs with digital signal processing (DSP) can provide robust performance for such systems to compensate for the severe channel impairment as the data rate continues to increase.

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.

3.4 A 36Gb/s PAM4 transmitter using an 8b 18GS/S DAC in 28nm CMOS

At data rates beyond 10Gb/s, most wireline links employ NRZ signaling. Serial NRZ links as high as 56Gb/s and 60Gb/s have been reported [1]. Nevertheless, as the rate increases, the constraints imposed by the channel, package, and die become more severe and do not benefit from process scaling in the same fashion that circuit design does. Reflections from impedance discontinuities in the PCB and package caused by vias and connectors introduce significant signal loss and distortions at higher frequencies. Even with an ideal channel, at every package-die interface, there is an intrinsic parasitic capacitance due to the pads and the ESD circuit amounting to at least 150fF, and a 50Ω resistor termination at both the transmit and receive ends resulting in an intrinsic pole at 23GHz or lower. In light of all these limitations, serial NRZ signaling beyond 60Gb/s appears suboptimal in terms of both power and performance. Utilizing various modulation techniques such as PAM4, one can achieve a higher spectral efficiency [2]. To enable such transmission formats, high-speed moderate-resolution data converters are required. This paper describes a 36Gb/s transmitter based on an 18GS/s 8b DAC implemented in 28nm CMOS, compliant to the new IEEE802.3bj standard for 100G Ethernet over backplane and copper cables [3].

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.