Switchable Feedback Capacitor Circuit for Low-Kickback Amplifiers

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Solution Overview

Problem

Capacitive amplifiers experience perturbations at switchable terminals of feedback capacitors during switching, leading to kickback into the circuitry connected to the amplifier's input, which can negatively impact transient performance.

Innovation Solution

The integration of kickback limiter circuitry connected to a switchable node of the capacitive amplifier helps mitigate these perturbations by holding the voltage level at the switchable node during switching, thereby reducing kickback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If feedback capacitors are switched around the amplifier during pre-charge phase, then the amplifier can perform pre-charge operation, but perturbations occur at the switchable terminals causing kickback into the input circuitry

Engineering Contradiction:

Improvepre-charge operation capabilityVSAvoidkickback into input circuitry

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A kickback limiter circuit is introduced as an intermediary component between the switched feedback capacitor and the amplifier input. This limiter circuit absorbs and dissipates the perturbation energy generated during capacitor switching, preventing it from propagating back into the sensitive input circuitry while allowing the pre-charge operation to proceed normally

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If switchable feedback capacitors are used in capacitive amplifiers, then the amplifier achieves versatile signal processing capability, but transient performance is degraded due to perturbations during reconnection

Engineering Contradiction:

Improvesignal processing capabilityVSAvoidtransient performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The kickback limiter circuit is designed to anticipate and counteract the perturbation effects before they can significantly degrade transient performance. By being pre-configured in the feedback path, the limiter is ready to immediately suppress any voltage spikes or oscillations that occur during capacitor reconnection, thereby protecting the transient response of the amplifier

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS12244278B2Capacitive amplifier with low kickback from switchable feedback capacitors

Publication Date: 2025.03.04 ANALOG DEVICES INT UNLTD CO

AI summary

A capacitive amplifier device and technique for mitigating the perturbation within the switchable terminals of a feedback capacitor which is produced by the switching activity performed as part of the device's operation. The capacitive amplifier contains feedback components which can be switched without producing significant kickback or poorly behaved transitions due to the inclusion of at least one dedicated circuit. The dedicated circuit is a kickback limiter circuitry which is connected to a switchable node and is designed to reduce the kickback. The technique for reducing the kickback produced can be achieved by connecting and activating the kickback limiter circuitry.