Afshin Momtaz
Broadcom
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Featured researches published by Afshin Momtaz.
IEEE Journal of Solid-state Circuits | 2002
Jun Cao; Michael M. Green; Afshin Momtaz; Kambiz Vakilian; David Chung; Keh-Chee Jen; Mario Caresosa; Xin Wang; Wee-Guan Tan; Yijun Cai; L. Fujimori; Armond Hairapetian
This paper presents the first fully integrated SONET OC-192 transmitter and receiver fabricated in a standard 0.18-/spl mu/m CMOS process. The transmitter consists of an input data register, 16-b-wide first-in-first-out (FIFO) circuit, clock multiplier unit (CMU), and 16:1 multiplexer to give a 10-Gb/s serial output. The receiver integrates an input amplifier for 10-Gb/s data, clock and data recovery circuit (CDR), 1:16 demultiplexer, and drivers for low-voltage differential signal (LVDS) outputs. An on-chip LC-type voltage-controlled oscillator (VCO) is employed by both the transmitter and receiver. The chipset operates at multiple data rates (9.95-10.71 Gb/s) with functionality compatible with the multisource agreement (MSA) for 10-Gb transponders. Both chips demonstrate SONET-compliant jitter characteristics. The transmitter 10.66-GHz output clock jitter is 0.065 UI/sub pp/ (unit interval, peak-to-peak) over a 50-kHz-80-MHz bandwidth. The receiver jitter tolerance is more than 0.4 UI/sub pp/ at high frequencies (4-80 MHz). A high level of integration and low-power consumption is achieved by using a standard CMOS process. The transmitter and receiver dissipate a total power of 1.32 W at 1.8 V and are packaged in a plastic ball grid array with a footprint of 11/spl times/11 mm/sup 2/.
IEEE Journal of Solid-state Circuits | 2010
Jun Cao; Bo Zhang; Ullas Singh; Delong Cui; Anand Vasani; Adesh Garg; Wei Zhang; Namik Kocaman; Deyi Pi; Bharath Raghavan; Hui Pan; Ichiro Fujimori; Afshin Momtaz
This paper presents the design of an analog-front-end (AFE) integrated into a DSP-based transceiver for both serial 10 Gbps KR-backplane and long-reach-multimode-fiber (LRM) applications. The receiver consists of a programmable gain amplifier (PGA) and a 6-bit 4-way time-interleaved ADC, which is digitally calibrated to compensate for the offset, gain and phase mismatches between the interleaved channels. With a 5 GHz input signal, the ADC achieves overall SNDR of 29 dB, while the measured SNDR of flash sub-ADC is 31.6 dB. The power efficiency FoM of the complete interleaved ADC is 1.4 pJ per conversion step. The PLL uses a calibrated LC-VCO and the TX features a full-rate 3-tap de-emphasis at the output. Inductively tuned buffers connected in tandem are employed to distribute the 10 GHz clock. Random and deterministic jitter measured at the TX output are 0.38 psrms and 2.65 pspp, respectively. Implemented in 65 nm CMOS technology, the AFE occupies an area of 3 mm2 and consumes 500 mW from a 1 V supply. BER of less than 10-15 is measured over legacy backplanes with 26 dB loss at Nyquist and the measured transceiver optical sensitivity is less than -13 dBm for all four LRM stressors, exceeding both the KR and the LRM specifications.
IEEE Journal of Solid-state Circuits | 2010
Afshin Momtaz; Michael M. Green
A 7-tap 40 Gb/s FFE using a 65 nm standard CMOS process is described. A number of broadbanding and calibration techniques are used, which allow high-speed operation while consuming 80 mW from a 1 V supply. ESD protection is added to 40 Gb/s IOs and an inexpensive plastic package is used to make the chip closer to a commercial product. The measured tap delay frequency response variation is less than 1 dB up to 20 GHz and tap-to-tap delay variation is less than 0.3 ps. More than 50% vertical and 70% horizontal eye opening from a closed input eye are observed. The use of a CMOS process enables further integration of this core into a DFE equalizer or a CDR/Demux based receiver.
IEEE Journal of Solid-state Circuits | 2001
Afshin Momtaz; Jun Cao; Mario Caresosa; Armond Hairapetian; David Chung; Kambiz Vakilian; Michael M. Green; Wee-Guan Tan; Keh-Chee Jen; Ichiro Fujimori; Yijun Cai
This paper presents the first fully integrated, SONET OC-48 (2.488/2.666 Gb/s) transceiver using a standard CMOS process. Careful design methodology combined with a standard CMOS technology allows performance exceeding SONET requirements with the added benefits of reduced power dissipation, higher integration levels, and simplified manufacturability as compared to other fabrication technologies. This chip, designed using a standard 0.18-/spl mu/m CMOS technology, has a total power dissipation of 500 mW and an rms jitter of 1 ps.
international solid-state circuits conference | 2002
Michael M. Green; Afshin Momtaz; Kambiz Vakilian; Xin Wang; Keh-Chee Jen; David Chung; Jun Cao; Mario Caresosa; Armond Hairapetian; Ichiro Fujimori; Yijun Cai
A fully integrated SONET OC-192 transmitter IC using a standard CMOS process consists of an input data register, FIFO, CMU, and 16:1 multiplexer to give a 10Gb/s serial output. A higher FEC rate, 10.7Gb/s, is supported. This chip, using a 0.18/spl mu/m process, exceeds SONET requirements, dissipating 450mW.
international solid-state circuits conference | 2009
Jun Cao; Bo Zhang; Ullas Singh; Delong Cui; Anand Vasani; Adesh Garg; Wei Zhang; Namik Kocaman; Deyi Pi; Bharath Raghavan; Hui Pan; Ichiro Fujimori; Afshin Momtaz
The demand for bandwidth has fueled the deployment of 10Gb/s traffic over legacy data links such as serial backplanes (10GBase-KR) and multimode fiber (10GBase-MMF) which were originally intended for much lower data rates [1,2]. Under severe channel impairments, a DSP-based transceiver provides robust performance and enables power/area scaling with processes [3–5]. This work describes a 65nm CMOS AFE integrated in a DSP-based PHY for 10Gb/s KR/MMF applications.
IEEE Journal of Solid-state Circuits | 2007
Afshin Momtaz; David Chung; Namik Kocaman; Jun Cao; Mario Caresosa; Bo Zhang; Ichiro Fujimori
A 10 Gb/s receiver, containing an adaptive equalizer, a clock and data recovery, and a de-multiplexer, is implemented in 0.13-mum CMOS. The chip is intended for long-haul optical fiber links where chromatic and polarization mode dispersions are reach-limiting factors. The equalization is performed by a continuous time filter and a two-tap decision feedback equalizer while automatic threshold and phase adjustments are embedded in the CDR. Use of an analog equalizer with digital adaptation garners total power dissipation of 950 mW. Error-free operation over 200 km of single mode fiber is demonstrated. With 140 km of single mode fiber, optical signal to noise ratio penalty is only 2dB. Differential group delay of 100 ps can also be tolerated
international solid-state circuits conference | 2001
Afshin Momtaz; Jun Cao; Mario Caresosa; A. Hairapitian; David Chung; K. Vakitian; Michael M. Green; B. Tan; Keh-Chee Jen; Ichiro Fujimori; G. Gutierrez; Yijun Cai
A fully-integrated transceiver in standard 0.18 /spl mu/m CMOS exceeds all SONET OC-48 requirements. The serial interfaces are 2.488 or 2.667 Gb/s CMC and the parallel ones are 622 or 666 Mb/s LVDS. The output clock rms jitter is 1 ps and total power consumption including all the input/output interfaces is 500 mW.
IEEE Journal of Solid-state Circuits | 2013
Namik Kocaman; Siavash Fallahi; Mahyar Kargar; Mehdi Khanpour; Ali Nazemi; Ullas Singh; Afshin Momtaz
An 8.5-11.5Gbps SONET transceiver with a referenceless CDR employing an algorithmic frequency acquisition scheme (without using any training sequence) is designed in a 65nm digital CMOS process. A modified digital quadricorrelator frequency detector (M-DQFD) is incorporated into an LC-based VCO coarse tuning adjustment. The transceiver complies with stringent SONET OC-192 jitter requirements. Within a 400μs acquisition time, the RX achieves a high-frequency jitter tolerance of 0.58UIpp at 10mVpp-diff input sensitivity. The TX serial output exhibits a random jitter (RJ) of 205fs (rms). The transceiver occupies 0.97mm2 and consumes 141mA at 1.0V.
IEEE Journal of Solid-state Circuits | 2014
Ullas Singh; Adesh Garg; Bharath Raghavan; Nick Huang; Heng Zhang; Zhi Chao Huang; Afshin Momtaz; Jun Cao
This paper describes a reconfigurable 4 × 28 Gb/s transceiver supporting 100 GbE/40 GbE standards. In each lane, the transmitter incorporates a 3-tap FIR with independent output phase adjustment, and the receiver has a half-rate CDR with a dedicated eye-monitor channel. There is a global resonant clock distribution network implemented using programmable distributed on-chip inductors. Implemented in a 40 nm CMOS process, the TX output measures 1.87 pspp DJ and 202 fsrms RJ. The RX jitter tolerance is 0.46 UIpp at 80 MHz with an input sensitivity of 27 mVpp-diff. The transceiver achieves BER on a channel with 20 dB loss at Nyquist, dissipating only 780 mW from a 0.9 V supply for all four lanes at 28 Gb/s operation.