Transactions on Machine Intelligence

Transactions on Machine Intelligence

A Novel Frequency Compensation Scheme for Stabilizing Three-Stage Amplifiers for a Wide range of Load Capacitors

Document Type : Original Article

Author
Department of Electrical Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran
Abstract
This paper introduces an innovative frequency compensation method designed to enhance the stability of three-stage amplifiers without imposing limitations on capacitive loads (CL). Traditional multistage amplifiers often encounter stability challenges due to varying CLs, but the proposed scheme overcomes this issue through an advanced compensation strategy. The approach integrates Miller capacitors in series with embedded current buffers and incorporates a feedback network connecting the second stage to the first. By effectively tuning the quality factor of non-dominant poles, the method achieves robust stability across a broad range of capacitive loads. The design was implemented using standard 180 nm CMOS technology, operating at a nominal supply voltage of 1.8 V. The compact layout occupies only 0.0026 mm² and consumes 23.38 µA of current. Open-loop frequency response simulations across different CL values, ranging from 0 to 100 nF, demonstrated a high gain of 119.3 dB. The average unity-gain bandwidths were measured at 4.872 MHz, 2.4 MHz, and 90.11 kHz for no load, 0.1 nF, and 100 nF loads, respectively. The paper also evaluates the amplifier's output settling performance under varying load conditions. Configured as a buffer with a 0.4 V input step, the amplifier exhibited stable behavior across all tested CLs. The measured 1% settling times were 0.48 µs for a 100 pF load and 19.92 µs for a 100 nF load, highlighting the effectiveness of the proposed compensation scheme in ensuring stability and performance for three-stage amplifiers.
Keywords

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Volume 7, Issue 4
Autumn 2024
Pages 286-295

  • Receive Date 02 August 2024
  • Revise Date 29 September 2024
  • Accept Date 22 December 2024