An adaptively pipelined mixed synchronous-asynchronous digital FIR filter chip operating at 1.3 gigahertz

  • Authors:
  • Montek Singh;Jose A. Tierno;Alexander Rylyakov;Sergey Rylov;Steven M. Nowick

  • Affiliations:
  • Department of Computer Science, University of North Carolina, Chapel Hill, NC;IBM Thomas J. Watson Research Center, Yorktown Heights, NY;IBM Thomas J. Watson Research Center, Yorktown Heights, NY;IBM Thomas J. Watson Research Center, Yorktown Heights, NY;Department of Computer Science, Columbia University, New York, NY

  • Venue:
  • IEEE Transactions on Very Large Scale Integration (VLSI) Systems
  • Year:
  • 2010

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Abstract

A high-throughput low-latency digital finite impulse response (FIR) filter has been designed for use in partial-response maximum-likelihood (PRML) read channels of modern disk drives. The filter is a hybrid synchronous-asynchronous design. The speed-critical portion of the filter is designed as a high-performance asynchronous pipeline sandwiched between synchronous input and output portions, making it possible for the entire filter to be embedded within a clocked system. A novel feature of the filter is that the degree of pipelining is dynamically variable, depending upon the input data rate. This feature is critical in obtaining a very low filter latency throughout the range of operating frequencies. The filter is a ten-tap six-bit FIR filter, fabricated in a 0.18-µm CMOS process. Resulting chips were fully functional over a wide range of supply voltages, and exhibited throughputs of over 1.3 giga-items/s, and latencies of 2-5 clock cycles. Interestingly, the filter throughput was limited by the synchronous portion of the chip; the internal asynchronous pipeline was estimated to be capable of significantly higher throughputs, around 1.8 giga-items/s. More importantly though, the adaptively pipelined nature of the filter allows it to offer a worst-case latency of only 10 ns, which is half the worst-case latency of the best previously reported comparable fully-synchronous implementation by Rylov et al.