Improved Frequency Compensation Technique for Three-Stage Amplifiers

Abstract

Improved frequency compensation is proposed for a three-stage amplifier with reduced total capacitance, improved slew rate, and reduced settling time. The proposed compensation uses an auxiliary feedback to increase the total effective compensation capacitance without loading the output node. The proposed compensation scheme is validated in simulation by implementing a three-stage amplifier driving 10 pF load capacitor in a 0.18 μm CMOS process. A detailed comparison of the compensation with a conventional nested Miller compensation is also presented. The simulation results showed a reduction in total compensation capacitance and improvement in slew rate compared to conventional nested Miller compensation and the other reported techniques in the literature.

Keywords

• frequency compensation
• nested Miller compensation
• high slew rate
• low settling time
• three-stage amplifier
• Routh–Hurwitz stability criterion