Class AB Common-Source Amplifier for Ultrasound Probe Impedance Matching

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Solution Overview

Problem

Ultrasonic transducer handles face challenges in transmitting sufficient electrical signal power to drive cables, leading to insufficient power transmission and impedance mismatch issues, which affect the quality of received signals and bandwidth in medical ultrasound applications.

Innovation Solution

A high-impedance, low-noise transconductance amplifier with a common-source class AB configuration and series-series local feedback is implemented, using complementary MOSFETs and operational amplifiers to enhance signal power transmission and impedance matching, reducing distortion and noise while maintaining low power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a transimpedance amplifier is used to maximize received current signal, then input impedance is low, but electrical impedance matching is not suitable

Engineering Contradiction:

Improvereceived current signalVSAvoidelectrical impedance matching

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent transforms the amplifier configuration from a transimpedance type to a transconductance type with high input impedance. This parameter change in the amplifier's electrical characteristics enables both high input impedance for current signal acquisition and adaptability for electrical impedance matching, resolving the contradiction between measurement precision and adaptability

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a common-source single or two-stage voltage amplifier is used for voltage sensing, then voltage sensing capability is improved, but bandwidth is limited

Engineering Contradiction:

Improvevoltage sensingVSAvoidbandwidth

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent replaces the conventional voltage sensing amplifier architecture with a transconductance amplifier architecture. This substitution fundamentally changes the sensing mechanism from voltage-based to current-based operation, enabling simultaneous achievement of voltage sensing capability through transconductance conversion and wide bandwidth performance

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Power

If the transducer handle transmits electrical signals, then signal power transmission is needed, but insufficient power is transmitted to drive the cable

Engineering Contradiction:

Improveelectrical signal powerVSAvoidsignal transmission efficiency

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The patent changes the amplifier configuration to a transconductance type with high input impedance, which optimizes the power transfer characteristics. This parameter change enables the amplifier to deliver sufficient electrical signal power to drive the cable while maintaining high transmission efficiency, resolving the contradiction between power transmission capability and transmission efficiency

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10469043B2Class AB common-source amplifier with constant transconductance

Publication Date: 2019.11.05 MICROCHIP TECHNOLOGY INC

AI summary

An ultrasound probe buffer is provided. The ultrasound probe buffer may include a high impedance amplifier having a common-source core stage with series-series local feedback. The high impedance amplifier may include a first MOSFET and a second MOSFET, wherein a source terminal of the first MOSFET is coupled to a source terminal of the second MOSFET.