SEMICONDUCTOR INTEGRATED CIRCUITS

A low-power low-voltage slew-rate enhancement circuit for two-stage operational amplifiers

Shu Chen, Xu Jun, Ye Fan and Ren Junyan

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Abstract: A novel circuit is presented in order to enhance the slew rate of two-stage operational amplifiers. The enhancer utilizes the class-AB input stage to improve current efficiency, while it works on an open loop with regard to the enhanced amplifier so that it has no effect on the stability of the amplifier. During the slewing period, the enhancer detects input differential voltage of the amplifier, and produces external enhancement currents for the amplifier, driving load capacitors to charge/discharge faster. Simulation results show that, for a large input step, the enhancer reduces settling time by nearly 50%. When the circuit is employed in a sample-and-hold circuit, it greatly improves the spur-free dynamic range by 44.6 dB and the total harmonic distortion by 43.9 dB. The proposed circuit is very suitable to operate under a low voltage (1.2 V or below) with a standby current of 200 μA.

Key words: slew-rate enhancementtwo-stage operational amplifierlow-voltage operationlow-power consumption

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    Received: 20 August 2015 Revised: 07 May 2012 Online: Published: 01 September 2012

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      Shu Chen, Xu Jun, Ye Fan, Ren Junyan. A low-power low-voltage slew-rate enhancement circuit for two-stage operational amplifiers[J]. Journal of Semiconductors, 2012, 33(9): 095007. doi: 10.1088/1674-4926/33/9/095007 Shu C, Xu J, Ye F, Ren J Y. A low-power low-voltage slew-rate enhancement circuit for two-stage operational amplifiers[J]. J. Semicond., 2012, 33(9): 095007. doi: 10.1088/1674-4926/33/9/095007.Export: BibTex EndNote
      Citation:
      Shu Chen, Xu Jun, Ye Fan, Ren Junyan. A low-power low-voltage slew-rate enhancement circuit for two-stage operational amplifiers[J]. Journal of Semiconductors, 2012, 33(9): 095007. doi: 10.1088/1674-4926/33/9/095007

      Shu C, Xu J, Ye F, Ren J Y. A low-power low-voltage slew-rate enhancement circuit for two-stage operational amplifiers[J]. J. Semicond., 2012, 33(9): 095007. doi: 10.1088/1674-4926/33/9/095007.
      Export: BibTex EndNote

      A low-power low-voltage slew-rate enhancement circuit for two-stage operational amplifiers

      doi: 10.1088/1674-4926/33/9/095007
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      National Science

      • Received Date: 2015-08-20
      • Accepted Date: 2012-01-16
      • Revised Date: 2012-05-07
      • Published Date: 2012-08-21

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