Variable-Current TIA Biasing for Low-Noise Ultrasound Signals
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Solution Overview
Problem
Ultrasound devices face challenges in effectively amplifying ultrasound signals while managing noise levels and power consumption, as existing amplifiers often prioritize one aspect over the other, leading to suboptimal performance and increased power usage.
Innovation Solution
A variable-current trans-impedance amplifier (TIA) with a differential input stage using N-P transistors and dynamic current biasing, allowing independent control of noise and linearity, and incorporating a variable feedback impedance to adjust power consumption and signal amplification during signal acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a constant current amplifier is used to maintain low noise floor, then noise performance is improved, but power consumption increases
Solution Approach 1:
The patent implements a variable current amplifier where the bias current is dynamically adjusted based on the signal acquisition phase. During the acquisition phase, higher current is used to maintain low noise floor for accurate signal detection. After acquisition, the current is reduced to minimize power consumption. This dynamic adaptation resolves the contradiction between maintaining low noise and reducing power usage.
Solution Approach 2:
The amplifier's operating current parameter is changed over time - using a first current value during signal acquisition to ensure low noise performance, and a second, lower current value during non-acquisition periods to reduce power consumption. This parameter variation allows the system to optimize both noise performance and energy efficiency at different operational stages.
2Reliability
If amplifier current is increased to improve signal amplification quality, then signal amplification is improved, but power consumption increases
Solution Approach 1:
The amplifier dynamically adjusts its current based on operational requirements. During signal acquisition when high amplification quality is needed, the amplifier operates at higher current. During idle or non-critical periods, it reduces current to save power while maintaining acceptable performance through other means such as oversampling or digital signal processing.
Solution Approach 2:
The amplifier operates in periodic cycles of high-current signal acquisition mode followed by low-current idle mode. This periodic switching between high and low current states allows the system to achieve high signal quality when needed while averaging lower power consumption over time.
Data Source
AI summary
A variable-current trans-impedance amplifier (TIA) for an ultrasound device is described. The TIA may be coupled to an ultrasonic transducer to amplify an output signal of the ultrasonic transducer representing an ultrasound signal received by the ultrasonic transducer. During acquisition of the ultrasound signal by the ultrasonic transducer, one or more current sources in the TIA may be varied. The variable-current trans-impedance amplifier may include multiple stages, including a first stage having N-P transistor pairs configured to receive an input signal and produce a single-ended amplified signal.