Superconducting single flux quantum 20 Gb/s clock recovery circuit
- Conductus, 969 West Sunnyvale, California 94086 (United States)
- University of California, Berkeley, California 94720 (United States)
A clock recovery circuit has been successfully tested at frequencies up to 20 GHz. This cell is designed for a rapid-single-flux-quantum (RSFQ) telecommunication data switch. It serves to set the receiver clock in phase with the incoming digital signal. The circuit consists of a dc-to-SFQ converter, ring oscillator [(RO) is a closed-loop RSFQ Josephson transmission line], confluence buffer, and an 8-bit binary counter. The input signal transforms to SFQ pulses, and each pulse resets the phase of the ring oscillator, giving a locking time of 1 bit. Thus, the pull-in (capture) range and hold-in (tracking) range are the same, and strictly depend on the encoding of the input signal. This range is estimated to be about 1 GHz at frequency 20 GHz, if the sequence of consecutive ONEs or ZEROs does not exceed 20 bits. The quality factor Q{sub RO} of ring oscillator is about 2000, which gives a jitter of 50 fs for a 35-junction RO. A sampling technique was used to demonstrate phase recovery (phase locking) with only one incoming pulse per 512 clock periods. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 531710
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 1 Vol. 71; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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