Ultrasonic Probe Precharge Circuit for Fast Echo Switching

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Solution Overview

Problem

Ultrasonic probes face challenges in switching between transmitting and receiving configurations due to protection requirements for low-voltage read circuits from high transmission voltages, which can lead to disturbance and incorrect echo reception, especially in arrays with shared terminals, necessitating fast and stable biasing to enable sonographic investigation in near fields.

Innovation Solution

The ultrasonic probe incorporates a bias circuit, a selector with high-voltage and low-voltage switches, and a precharge circuit to alternately couple and decouple the transducer and amplification stage, using a current-mirror configuration for precharge and bias currents to stabilize the intermediate node voltage, allowing for efficient switching between configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the read circuits are protected from high transmission voltages by switching, then the reliability of the read circuits is improved, but the switching time increases and fast switching is compromised

Engineering Contradiction:

Improveprotection of read circuitsVSAvoidswitching speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The precharge circuit performs preliminary action by precharging the intermediate node to the bias voltage before the switching operation. This preliminary preparation eliminates voltage transients and discharge currents that would otherwise occur during switching, enabling immediate stable reception without extending switching time.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the transducers are connected with shared terminals to reduce dimensions and production costs, then the manufacturing cost and device size are reduced, but the stability of biasing during switching deteriorates

Engineering Contradiction:

Improveproduction cost and dimensionsVSAvoidbiasing stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The intermediate node serves as an intermediary between the transducer and the read circuit, with the precharge circuit specifically managing its voltage state. By precharging this intermediate node, the system maintains stable biasing conditions during the shared-terminal configuration, preventing discharge currents that would destabilize the biasing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the amplification stage is quickly coupled to the transducer for near-field investigation, then the productivity for near-field imaging is improved, but noise and disturbance from voltage transients increase

Engineering Contradiction:

Improvenear-field investigation capabilityVSAvoidnoise and disturbance

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The precharge circuit performs preliminary action by establishing the correct voltage on the intermediate node before coupling occurs. This eliminates voltage transients and associated noise/disturbance, enabling immediate accurate reception of near-field echoes without the harmful effects that would normally accompany fast switching.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables fast and stable switching between transmitting and receiving configurations, minimizing noise and ensuring accurate echo reception, even in near-field sonographic investigations, while reducing power consumption and maintaining probe integrity.

Implementation Method 1

a precharge circuit configured to determine a precharge voltage on the intermediate node as a function of the bias voltage before the amplification stage and the transducer are coupled by the control unit

Methodology Applied

Scientific EffectElectrical precharging: Electrical Accumulator

Implementation Method 2

The transducers are configured to convert pressure waves into electrical signals and vice versa and may, for example, be piezoelectric transducers

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

The transducers are configured to convert pressure waves into electrical signals and vice versa and may, for example, be piezoelectric transducers or else membrane capacitive transducers

Methodology Applied

Scientific EffectCapacitive transduction: Capacitance

Implementation Method 4

the precharge generator is fitted into current-mirror configuration to the bias generator. In an embodiment, the precharge current and the bias current are in a mirror ratio

Methodology Applied

Scientific EffectCurrent mirror effect:

Data Source

PatentUS10114114B2Ultrasonic probe with precharge circuit and method of controlling an ultrasonic probe

Publication Date: 2018.10.30 STMICROELECTRONICS SRL

AI summary

An ultrasonic probe includes: an ultrasonic transducer; an amplification stage; a bias circuit, which determines a bias voltage on an input terminal of the amplification stage; and a selector having an intermediate node, a high-voltage switch between the intermediate node and the transducer, and a first low-voltage switch between the intermediate node and the input terminal. A control unit controls the high-voltage switch and the first low-voltage switch so as to alternately couple and decouple the amplification stage and the transducer. A precharge circuit determines a precharge voltage on the intermediate node as a function of the bias voltage, before the amplification stage and the transducer are coupled.