An Eight lanes 7Gb/s/pin Source Synchronous Single-Ended RX with Equalization and Far-End Crosstalk Cancellation for Backplane Channels

This paper presents a versatile crosstalk cancellation scheme for single-ended multi-lane backplane links. System-level investigations show that a scheme, which combines analog filters and decision-feedback crosstalk compensation on the receiver (RX) side only, can efficiently remove crosstalk patterns in straight channels as well as boards with reflections due to via stubs. An eight-lane single-ended RX has been manufactured in 32-nm SOI CMOS to validate our findings. A CTLE and eight-tap decision feedback equalizer equalize the channel without transmitter feedforward equalizer. A continuous time crosstalk canceller reduces precursors by nearest neighbors, while the residual postcursors from all aggressors are suppressed by direct feedback 7x8-tap decision-feedback crosstalk canceller (DFXC). Measurements with flip-chip packaged RX show that the RX macro can equalize both a 30-dB insertion loss single-ended channel with 0-dB signal-to-crosstalk at Nyquist and a channel with 28-dB attenuation with the signal-to-crosstalk ratio of 6 dB combined with reflections due to via stubs. The RX operates up to 7 Gb/s/pin with PRBS11 data at bit error rate (BER) <10⁻¹², and occupies 300x350 μm² with an energy efficiency of 5.9 mW/Gb/s from 1-V supply

A 5.9mW/Gb/s 7Gb/s/pin 8-Lane Single-Ended RX with Crosstalk Cancellation Scheme using a XCTLE and 56-tap XDFE in 32nm SOI CMOS

This work reports an 8-lane single-ended RX featuring compact and low power far-end crosstalk (FEXT) cancellation circuits. The RX data-path consists of a cross continuous-time linear equalizer (XCTLE) to remove FEXT by nearest aggressors within the channel bundle. Residual post-cursor FEXT is suppressed by a direct feedback 7x8-tap cross decision feedback equalizer (XDFE). A CTLE and 8-tap DFE equalize single-ended channels with 28dB insertion loss at Nyquist frequency without TX FFE. The circuit, fabricated in 32nm SOI CMOS, was measured to receive 7Gb/s/pin PRBS11 data at BER< 10^-12 with 12.5%UI margin. It occupies 300x350um2 with an energy efficiency of 5.9mW/Gb/s

Energy-Efficient High-Speed SAR ADCs in CMOS

An ADC featuring a new architecture for an 8 b 64× interleaved CMOS ADC running at up to 100 GHz sampling frequency is presented. The ADC fulfills all specifications for 100 Gb/s ITU-OTU4 communication over long-distance optical fiber channels. It is based on a SAR ADC, known for its superior energy efficiency and suitability for deep-submicron digital CMOS processes, as the comparator is the only true analog element. Several improvements to existing SAR ADC architectures are presented. Alternate comparators are used to increase the sampling speed at no power and area penalty, and dynamic memory is used to reduce latency in the CDAC feedback. A deep-trench capacitor-based reference buffer significantly reduces power at low output impedance, and a differential CDAC with constant common mode and fractional reference voltages optimizes comparator performance and silicon area. The 64× interleaved ADC consists of a dedicated sampling and interleaving block and 64 SAR ADCs. Four interleaved passive samplers based on a sampling switch with in-line 1:4 demultiplexer provide an initial 1:16 interleaving with high linearity and more than 20 GHz input bandwidth while using only a single supply voltage

Implementation of Low-Power 6–8 b 30–90 GS/s Time-Interleaved ADCs With Optimized Input Bandwidth in 32 nm CMOS

A model for voltage-based time-interleaved sampling is introduced with two implementations of highly interleaved analog-to-digital converters (ADCs) for 100 Gb/s communication systems. The model is suitable for ADCs where the analog input bandwidth is of concern and enables a tradeoff between different architectures with respect to the analog input bandwidth, the hold time of the sampled signal, and constraints on the clock path. The two ADCs at 6 and 8 b resolution implement inline demux sampling with 32× and 64× interleaving to achieve 36 GS/s at 110 mW and 90 GS/s at 667 mW, respectively. The analog input bandwidth of both ADCs exceeds 20 GHz. The SNDR of the 64× interleaved ADC is above 36 dB up to 6.1 GHz and above 33 dB up to 19.9 GHz at 90 GS/s, and the SNDR of the 32× interleaved ADC exceeds 31.6 dB up to Nyquist at 36 GS/s. The 32×and 64× interleaved ADCs are optimized for area and occupy 0.048 and 0.45 mm2, respectively, in 32 nm CMOS SOI technology

A 110mW 6 Bit 36GS/S Interleaved SAR ADC for 100 GBE Occupying 0.048mm2 in 32nm SOI CMOS

An area- and power-optimized asynchronous 32x interleaved SAR ADC achieving 36 GS/s at 110mW and 1V supply on the interleaver and 0.9V on the SAR ADCs is presented. The ADC features a 2-channel interleaver with data demultiplexing for enhanced bandwidth, a power- and area optimized binary SAR ADC, and an area optimized clocked reference buffer with a tunable constant current source. It achieves 32.6 dB SNDR up to 3GHz and 31.6 dB up to 18 GHz input frequency and 98 fJ/conversion-step with a core chip area of 340x140 um2 in 32nm SOI CMOS technology