Publications by Author: Agrawal, Ankur

2011
Ankur Agrawal, Kumar Hanumolu, and Gu Wei. 9/19/2011. “Area efficient phase calibration of a 1.6 GHz multiphase DLL.” In 2011 IEEE Custom Integrated Circuits Conference (CICC), Pp. 1–4. IEEE. Publisher's VersionAbstract
This paper describes a digital calibration scheme that corrects for phase spacing errors in a multiphase clock generating delay-locked loop (DLL). The calibration scheme employs sub-sampling using a frequency-offset clock with respect to the DLL reference clock, to measure phase-offsets. The phase-correction circuit uses one digital-to-analog converter across eight variable-delay buffers to reduce the area consumption by 62%. The test-chip, designed in a 130 nm CMOS process, demonstrates a 8-phase 1.6 GHz DLL with a worst-case phase error of 450 fs.
Area efficient phase calibration of a 1.6 GHz multiphase DLL
2009
Ankur Agrawal, Andrew Liu, Pavan Kumar Hanumolu, and Gu-Yeon Wei. 8/2009. “An 8$, times, $5 Gb/s Parallel Receiver With Collaborative Timing Recovery.” IEEE Journal of Solid-State Circuits, 44, 11, Pp. 3120–3130. Publisher's VersionAbstract
This paper presents the design of an 8 channel, 5 & Gb/s per channel parallel receiver with collaborative timing recovery and no forwarded clock. The receiver architecture exploits synchrony in the transmitted data streams in a parallel interface and combines error information from multiple phase detectors in the receiver to produce one global synthesized clock. This collaborative timing recovery scheme enables wideband jitter tracking without increasing the dithering jitter in the synthesized clock. Circuit design techniques employed to implement this receiver architecture are discussed. Experimental results from a 130 nm CMOS test chip demonstrate the enhanced tracking bandwidth and lower dithering jitter of the recovered clock.
An 8$, times, $5 Gb/s Parallel Receiver With Collaborative Timing Recovery
2008
Ankur Agrawal, Pavan Kumar Hanumolu, and Gu-Yeon Wei. 9/21/2008. “A 8 x 5 Gb/s source-synchronous receiver with clock generator phase error correction.” In 2008 IEEE Custom Integrated Circuits Conference, Pp. 459–462. IEEE. Publisher's VersionAbstract
This paper describes the design and implementation of a 8times5 Gb/s source-synchronous receiver in a 0.13 mum CMOS technology. The receiver employs a cascaded-DLL architecture that avoids filtering of the jitter on the received clock to enhance jitter tolerance bandwidth. A technique is proposed to correct phase spacing mismatch in DLLs that reduces the error standard deviations by more than 40% and improves receiver timing margins.
A 8 x 5 Gb/s source-synchronous receiver with clock generator phase error correction