Amplifier Phase Compensation Using HPF for Fast Stable Response

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional phase compensation circuits in differential amplifiers result in slow response speeds due to low open loop gain frequency, leading to potential oscillation issues regardless of the capacitance value of the output capacitor.

Innovation Solution

A phase compensation circuit incorporating a high-pass filter and a transconductance amplifier to filter signals above a specified frequency, preventing oscillation while maintaining fast response speed by adjusting impedance and pole placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional phase compensation circuit with capacitor and resistor is used, then oscillation is prevented regardless of output capacitor capacitance, but the response speed becomes slow due to low open loop gain frequency

Engineering Contradiction:

Improveoscillation preventionVSAvoidresponse speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The invention changes the frequency characteristics of the phase compensation circuit by replacing the conventional capacitor-resistor configuration with a high-pass filter and transconductance amplifier. This parameter change in the circuit topology allows the open loop gain frequency to be increased, thereby improving response speed while maintaining oscillation prevention capability across different output capacitor capacitance values.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention substitutes the passive capacitor-resistor phase compensation mechanism with an active high-pass filter and transconductance amplifier system. This substitution enables dynamic control of the compensation characteristics, allowing fast response speed to be achieved while maintaining reliability across varying capacitance conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If the open loop gain frequency is increased to improve response speed, then response speed improves, but oscillation may occur with certain output capacitor capacitance values

Engineering Contradiction:

Improveresponse speedVSAvoidoscillation prevention

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The high-pass filter and transconductance amplifier configuration provides universal oscillation prevention that works across a wide range of output capacitor capacitance values. The circuit design achieves this by creating compensation characteristics that are less sensitive to variations in output capacitance, allowing the same circuit topology to maintain both fast response speed and reliable oscillation prevention regardless of the specific capacitance value used.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250309846A1Phase compensation circuit and amplifier including the same

Publication Date: 2025.10.02 ABLIC INC

AI summary

Provided is an amplifier. An amplifier includes a differential amplifier; and a phase compensation circuit including an input port and an output port. The phase compensation circuit includes a transconductance amplifier including a first input port, a second input port, and an output port connected to an output node of the differential amplifier; and a high-pass filter (HPF) configured to pass, among signals output from the differential amplifier, a signal having a frequency at a specified frequency or higher and supply it to the first input port and the second input port.