Operational Transconductance Amplifier With Class-B Slew-Rate Boosting for Fast High-Performance Switched-Capacitor Circuits
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© 2004-2012 IEEE. In this paper, a technique for slew-rate (SR) boosting suitable for switched-capacitor circuits is proposed. The proposed technique makes use of a class-B auxiliary amplifier that generates a compensating current only when high SR is demanded by large signals. The proposed architecture employs simple circuitry to detect the need for a large output current by employing a highly sensitive pre-amplifier followed by a class-B amplifier. The functionality of the class-B transconductance amplifier is dictated by a predefined hysteresis, and operates in parallel with the main amplifier. The proposed solution demands small static power (under 20% of main amplifier power) due to its class-B nature. The experimental results in a 40-nm CMOS technology show more than 45% reduction in slew time, and a 28% shorter slew time for 1% settling time when used in a typical 4.5 bit/stage block commonly used in pipelined analog-to-digital converters. Compared with the core amplifier, HD3 at 500 MHz reduces by more than 10 dB when the SR boosting circuit is activated.
author list (cited authors)
Naderi, M. H., Prakash, S., & Silva-Martinez, J.