Data Recovery IC Research Articles

3.125-to-28.125 Gb/s 4.72 mW/Gb/s Multi- Standard Parallel Transceiver Supporting Channel-Independent Operation in 40-nm CMOS

This paper presents a 3.125-to-28.125 Gb/s dual-lane multi-standard parallel transceiver supporting channel-independent operation. Network equipment supports multiple data rates to encompass diversified communication standards. However, network equipment supports only a fixed number of channels at each supported data rate. This lack of flexibility limits the utilization rate of the network equipment. This study proposes a clock and data recovery (CDR) IC to obtain utilization flexibility and scalability in each channel with complete channel independency. The CDR IC achieves a wide tuning capability for data rates ranging from 3.125 to 28.125 Gb/s with low clock jitter owing to the use of injection-locked oscillators in each channel. Each CDR lane generates a channel-independent injection clock signal with a fixed-frequency global clock signal using a variable clock divider and a phase rotator with the proposed harmonic distortion compensator. In addition, a frequency tracking loop is proposed using a bang-bang phase detector-based natural frequency detector to align the natural frequency of the injection-locked oscillator with the input data rate, thereby suppressing the injection spur. The test chip fabricated in a 40 nm CMOS exhibits a power efficiency of 4.72 mW/Gb/s, while generating a recovered clock jitter of 976 fsrms at a data rate of 25.78125 Gb/s.

An Electronic Dispersion Compensation Transceiver for 10- and 28-Gb/s Directly Modulated Lasers-Based Optical Links

This paper presents an electronic dispersion compensation (EDC) transceiver to encompass extended reach of both 10- and 28-Gb/s directly modulated lasers (DMLs). In DML-based links, direct modulation of laser diodes induces power-dependent frequency chirp on the generated optical signals, which causes severe chromatic dispersion as well as pattern dependence on the received signal after optical fiber transmission. Such time-varying nature of the dispersion makes conventional equalization methods ineffective for compensation. The proposed EDC-based clock and data recovery (CDR) IC overcomes the chirp-induced dispersion via a linear equalizer followed by a double-sampling decision feedback equalizer (DFE) at the receiver and a pattern-dependent pulse shaping filter at the transmitter. The chirp-managed EDC improves the receiver sensitivity at a bit error rate (BER) of 10−6 by 1.3 dB in a 3-km link using a DML at a modulation rate of 28 Gb/s, where transient chirp is dominant, and by more than 7 dB in a 105-km link at 10 Gb/s, where adiabatic chirp is dominant. The chip prototype is fabricated in a 40-nm CMOS process and packaged in a flip-chip ball grid array (BGA). The single-chip IC containing dual-lane transceivers and a global clock generator (CG) occupies an active area of 2.8 mm2. The test chip consumes 236 mW, wherein a single-lane transceiver consumes 105.5 mW and a global CG consumes 25 mW from a 0.9-V supply at 28 Gb/s.

A DC-to-12.5 Gb/s 9.76 mW/Gb/s All-Rate CDR With a Single <italic>LC</italic> VCO in 90 nm CMOS

A dual-lane DC-to-12.5 Gb/s all-rate clock and data recovery (CDR) IC with a single LC voltage-controlled oscillator is fabricated in a 90 nm CMOS. An all-rate clock divider with an asynchronous phase calibration scheme is employed to generate all-rate clock signals without a phase mismatch or duty cycle distortion. The IC features an automatic loop gain control scheme that adjusts the bandwidth of a CDR in the background for optimal bit error rate (BER) performance by monitoring the phase difference between the incoming data and the recovered clock signal. The proposed CDR consumes 244 mW at 12.5 Gb/s under dual-lane operation with an input sensitivity of 12 mVpp,diff. The CDR supports referenceless allrate operation with a BER <; 10 -12 on PRBS31 and compensates for 20 dB of channel loss using a continuous-time linear equalizer (CTLE), a one-tap decision feedback equalizer (DFE), and a three-tap pre-emphasis filter. The power efficiency of the test chip is 9.76 mW/Gb/s.

A 400 Mb/s∼2.5 Gb/s Referenceless CDR IC Using Intrinsic Frequency Detection Capability of Half-Rate Linear Phase Detector

A 400 Mb/s∼2.5 Gb/s referenceless clock and data recovery (CDR) IC is presented. This paper shows that the half-rate linear phase detector (PD) has not only phase detection capability but also single-sided frequency detection capability in itself. By using this intrinsic frequency detection capability of the half-rate linear PD, a CDR can be implemented in the single loop architecture without both an external reference clock and a separate frequency detector. For verification, a prototype CDR IC was fabricated in a 0.13 $\mu\text{m}$ CMOS process. With 2.5 Gb/s, $2^{31} - 1$ pseudorandom binary sequence (PRBS), the measurement results show that the frequency acquisition time is 17 $\mu\text{s}$ , the bit error rate (BER) is better than 10−12, the jitter of the recovered clock is 8.6 $\text{ps}_{\mathrm{rms}}$ and the out-of-band jitter tolerance is 0.32 $\text{UI}_{\mathrm{pp}}$ .

0.6–2.7-Gb/s Referenceless Parallel CDR With a Stochastic Dispersion-Tolerant Frequency Acquisition Technique

A 0.6-2.7-Gb/s phase-rotator-based four-channel digital clock and data recovery (CDR) IC featuring a low-power dispersion-tolerant referenceless frequency acquisition technique is presented. A quasi-periodic reference clock signal extracted directly from a dispersed input signal is distributed to digitally controlled phase rotators in the CDR ICs for phase acquisition. A multiphase frequency acquisition scheme is employed for the reduction of the clock jitter. The measurement results show that the proposed design offers a lower frequency offset and clock noise floor under channel dispersion, as compared with conventional designs. The proposed four-channel digital CDR IC is fabricated in a 90-nm CMOS process. The figure of merit for a single channel is 8 mW/Gb/s such as a feedforward equalizer, a decision-feedback equalizer, and a referenceless CDR.

A 10-Gb/s CMOS CDR and DEMUX IC With a Quarter-Rate Linear Phase Detector

This paper presents a 10-Gb/s clock and data recovery (CDR) and demultiplexer IC in a 0.13-mum CMOS process. The CDR uses a new quarter-rate linear phase detector, a new data recovery circuit, and a four-phase 2.5-GHz LC quadrature voltage-controlled oscillator for both wide phase error pulses and low power consumption. The chip consumes 100 mA from a 1.2-V core supply and 205 mA from a 2.5-V I/O supply including 18 preamplifiers and low voltage differential signal (LVDS) drivers. When 9.95328-Gb/s 231-1 pseudorandom binary sequence is used, the measured bit-error rate is better than 10-15 and the jitter tolerance is 0.5UIpp, which exceeds the SONET OC-192 standard. The jitter of the recovered clock is 2.1 psrms at a 155.52MHz monitoring clock pin. Multiple bit rates are supported from 9.4 Gb/s to 11.3 Gb/s

Input-Matching and Offset-Cancelling Networks for Limiting Amplifiers in Optical Communication Systems

The diffusion of optical communication systems in the access network and for short-haul datacom applications requires the use of low-cost plastic packages: the functional block most affected is the limiting amplifier, that is often the first stage of the Clock and Data Recovery (CDR) IC. In this paper we illustrate the design issues of the input-matching and offset-cancelling network for a differential limiting amplifier for optical communication systems, with particular emphasis on the effect of bond wires. We discuss the limitations of passive feedback networks when used both for offset suppression and for input matching, and propose a topology that overcomes such limitations by using an active feedback loop. A 50 ?-loaded differential pair is used to achieve input matching and high offset suppression, and its buffering action desensitizes the input matching from the effect of the bond wires connecting off-chip filtering capacitors. Very good performance even with low cost plastic packages can be achieved by solving the trade-off between power consumption, offset suppression and the value of the low-pass filtering capacitors. Design examples of CDR IC's for 2.5 Gb/s optical systems are presented to compare the proposed topology with solutions based on passive feedback networks.

Acquisition-time estimation for over 10 Gbit/s clock and data recovery ICs

A method to estimate the acquisition time for the clock and data recovery (CDR) IC using the linear phase-locked loop (PLL) technique is proposed. Estimations using the method follow the measured acquisition time for the PLL with any loop parameters, which makes it possible to design the CDR IC for various targets.

PLL design technique by a loop-trajectory analysis taking decision-circuit phase margin into account for over-10-Gb/s clock and data recovery circuits

A design technique for an over-10-Gb/s clock and data recovery (CDR) IC provides good jitter tolerance and low jitter. To design the CDR using a PLL that includes a decision circuit with a certain phase margin affecting the pull-in performance, we derived a simple expression for the pull-in range of the PLL, which we call the limited pull-in range, and used it for the pull-in performance evaluation. The method allows us to quickly and easily compare the pull-in performance of a conventional PLL with a full-rate clock and a PLL with a half-rate clock, and we verified that the half-rate PLL is advantageous because of its wider frequency range. For verification of the method, we fabricated a half-rate CDR with a 1:16 DEMUX IC using commercially available Si bipolar technology with f/sub T/=43 GHz. The half-rate clock technique with a linear phase detector, which is adopted to avoid using the binary phase detector often used for half-rate CDR ICs, achieves good jitter characteristics. The CDR IC operates reliably up to over 15 Gb/s and achieves jitter tolerance with wide margins that surpasses the ITU-T specifications. Furthermore, the measured jitter generation is less than 0.4 ps rms, which is much lower than the ITU-T specification. In addition, the CDR IC can extract a precise clock signal under harsh conditions, such as when the bit error rate of input data is around 2/spl times/10/sup -2/ due to a low-power optical input of -24 dBm.

A 40-43-Gb/s clock and data recovery IC with integrated SFI-5 1:16 demultiplexer in SiGe technology

A fully integrated OC-768 clock and data recovery IC with SFI-5 1:16 demultiplexer is designed in a 120-GHz/100-GHz (f/sub T//f/sub MAX/) SiGe technology. The 16 2.5-Gb/s outputs and additional deskew channel are compliant with the Serdes Framer Implementation Agreement Level 5 specification. The measured bit-error rate is <10/sup -15/. The measured jitter tolerance exceeds the mask specified in G.8251. The IC operates with 1.8-V and -5.2-V supplies and dissipates 7.5 W.

Clock and data recovery IC for 40-Gb/s fiber-optic receiver

The integrated clock and data recovery (CDR) circuit is a key element for broad-band optical communication systems at 40 Gb/s. We report a 40-Gb/s CDR fabricated in indium-phosphide heterojunction bipolar transistor (InP HBT) technology using a robust architecture of a phase-locked loop (PLL) with a digital early-late phase detector. The faster InP HBT technology allows the digital phase detector to operate at the full data rate of 40 Gb/s. This, in turn, reduces the circuit complexity (transistor count) and the voltage-controlled oscillator (VCO) requirements. The IC includes an on-chip LC VCO, on-chip clock dividers to drive an external demultiplexer, and low-frequency PLL control loop and on-chip limiting amplifier buffers for the data and clock I/O. To our knowledge, this is the first demonstration of a mixed-signal IC operating at the clock rate of 40 GHz. We also describe the chip architecture and measurement results.

A fully integrated 40-Gb/s clock and data recovery IC with 1:4 DEMUX in SiGe technology

In this paper, a fully integrated 40-Gb/s clock and data recovery (CDR) IC with additional 1:4 demultiplexer (DEMUX) functionality is presented. The IC is implemented in a state-of-the-art production SiGe process. Its phase-locked-loop-based architecture with bang-bang-type phase detector (PD) provides maximum robustness. To the authors' best knowledge, it is the first 40-Gb/s CDR IC fabricated in a SiGe heterojunction bipolar technology (HBT). The measurement results demonstrate an input sensitivity of 42-mV single-ended data input swing at a bit-error rate (BER) of 10/sup -10/. As demonstrated in optical transmission experiments with the IC embedded in a 40-Gb/s link, the CDR/DEMUX shows complete functionality as a single-chip-receiver IC. A BER of 10/sup -10/ requires an optical signal-to-noise ratio of 23.3 dB.

SiGe clock and data recovery IC with linear-type PLL for 10-Gb/s SONET application

An integrated 10 Gb/s clock and data recovery (CDR) circuit is fabricated using SiGe technology, It consists of a linear-type phase-locked loop (PLL) based on a single-edge version of the Hogge phase detector, a LC-tank voltage-controlled oscillator (VCO) and a tri-state charge pump. A PLL equivalent model and design method to meet SONET jitter requirements are presented. The CDR was tested at 9.529 GB/s in full operation and up to 13.25 Gb/s in data recovery mode. Sensitivity is 14 mV/sub pp/ at a bit error rate (BER)=10/sup -9/. The measured recovered clock jitter is less than 1 ps RMS. The IC dissipates 1.5 W with a -5 V power supply.

A 2.5-Gb/s clock and data recovery IC with tunable jitter characteristics for use in LANs and WANs

A 2.5-Gb/s monolithic clock and data recovery (CDR) IC using the phase-locked loop (PLL) technique is fabricated using Si bipolar technology. The output jitter characteristics of the CDR can be controlled by designing the loop-gain design and by using the switched-filter PLL technique. The CDR IC can be used in local-area networks (LANs) and in long-haul backbone networks or wide-area networks (WANs). Its power consumption is only 0.4 W. For LANs, the jitter generation of the CDR when the loop gain is optimized is 1.2 ps (0.003 UI). The jitter characteristics of the CDR optimized for WANs meet all three types of STM-I6 jitter specifications given in ITU-T Recommendation G.958. This is the first report on a CDR that can be used for both LAN's and WAN's. This paper also describes the design method of the jitter characteristics of the CDR for LANs and WANs.

Jitter-suppressed low-power 2.5 Gbit/s clock anddata recovery IC without high-Q components

A 2.5 bit/s monolithic clock and data recovery (CDR) IC using a PLL technique is fabricated using Si bipolar technology. The CDR IC provides suppressed jitter characteristics with a low power consumption. To our knowledge, this is the first report of a single-chip 2.5 Gbit/s CDR IC, the jitter characteristics of which meet all three types of STM-16 jitter specifications described in ITU-T recommendations.