Buffered Voltage Follower for Bandwidth and Linearity

Solution Overview

Problem

Conventional source followers suffer from reduced performance and signal quality due to nonlinear parasitic capacitance caused by electrically connecting the body and source, which affects bandwidth and linearity.

Innovation Solution

A voltage follower design that decouples the body and source of the transistor, using a buffer circuit to maintain equal body and source voltages, thereby eliminating the body effect and reducing parasitic capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the body and source are electrically connected to eliminate the body effect, then the body effect is eliminated, but nonlinear parasitic capacitance is introduced which reduces bandwidth and linearity

Engineering Contradiction:

Improvebody effect eliminationVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent segments the body and source connections by introducing a buffer circuit that electrically isolates the body from the source while maintaining voltage equality. This segmentation eliminates the direct parasitic capacitance path while preserving the body effect elimination through buffered voltage coupling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buffer circuit acts as an intermediary between the source and body connections. It receives the source voltage signal and provides it to the body terminal, maintaining voltage equality without creating direct parasitic capacitance. This intermediary approach resolves the contradiction by mediating the voltage relationship while avoiding the harmful direct connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the body and source are electrically connected to eliminate the body effect, then the body effect is eliminated, but the linearity of the output signal is reduced

Engineering Contradiction:

Improvebody effect eliminationVSAvoidsignal linearity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent segments the body and source connections by introducing a buffer circuit that electrically isolates the body from the source while maintaining voltage equality. This segmentation eliminates the direct parasitic capacitance path while preserving the body effect elimination through buffered voltage coupling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buffer circuit acts as an intermediary between the source and body connections. It receives the source voltage signal and provides it to the body terminal, maintaining voltage equality without creating direct parasitic capacitance. This intermediary approach resolves the contradiction by mediating the voltage relationship while avoiding the harmful direct connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250251748A1Voltage follower

Publication Date: 2025.08.07 REALTEK SEMICON CORP

AI summary

A voltage follower has a first input terminal and a first output terminal and includes a transistor, a first load, and a buffer circuit. The transistor has a gate, a source, a drain, and a body. The gate is coupled to the first input terminal, the source is coupled to the first output terminal, and the drain is coupled to a first reference voltage. The first load is coupled between the source and a second reference voltage. The buffer circuit has a second input terminal and a second output terminal. The second input terminal is coupled to the gate, and the second output terminal is coupled to the body.