Wideband Variable Gain Amplifier Clipping for ADC Overload Control
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Solution Overview
Problem
Conventional variable gain amplifiers in ultrasound systems often amplify analog receive signals beyond the allowable range for ADC input, leading to potential ADC malfunction and inaccurate ultrasound image formation due to signal overload.
Innovation Solution
A wide-band variable gain amplifier with clipping functions, utilizing input and output units, first and second clipping units, and amplifiers to regulate signal amplitudes within predetermined voltage ranges, preventing overload and ensuring proper ADC operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the variable gain amplifier amplifies analog receive signals with high gain to compensate for signal attenuation, then the signal amplitude is increased for better image quality, but the signal may exceed the allowable amplitude range for ADC input causing overload and malfunction
Solution Approach 1:
A clipping circuit is introduced as an intermediary component between the variable gain amplifier and the ADC. This clipping circuit acts as a mediator that limits the signal amplitude to within the ADC's allowable range, preventing overload while allowing the amplifier to operate at high gain for improved signal compensation.
Solution Approach 2:
The clipping function is applied in advance before the signal enters the ADC. By preliminarily limiting the amplitude range of the amplified signal, the system prevents potential overload conditions before they can cause ADC malfunction, ensuring reliable operation.
2Measurement precision
If the variable gain amplifier increases gain to compensate for deep tissue signal attenuation, then distant tissue signals become detectable, but the recovery time increases due to overload conditions
Solution Approach 1:
The clipping circuit serves as a protective intermediary that prevents overload conditions while maintaining high gain operation. By limiting the maximum amplitude before it reaches the ADC, the clipping circuit eliminates the recovery time penalty that would otherwise occur during overload events, allowing continuous high-gain operation for deep tissue detection.
3Measurement precision
If conventional variable gain amplifiers amplify signals beyond ADC input range, then signal compensation is improved, but ADC malfunction occurs leading to inaccurate ultrasound image formation
Solution Approach 1:
The clipping circuit is positioned as an intermediary between the amplifier and ADC, ensuring that signal compensation can be performed with high gain while the clipping function prevents amplitude excursions that would cause ADC malfunction and image distortion.
Solution Approach 2:
The clipping circuit provides automatic amplitude control through its inherent limiting characteristic, continuously monitoring and restricting the signal amplitude to remain within the safe operating range of the ADC, thereby preventing image formation errors.
Data Source
AI summary
The present invention relates to a variable gain amplifier. The variable gain amplifier includes an input unit including first and second input nodes and an output node, the input unit being configured to receive first and second input signals. The variable gain amplifier further includes a first clipping unit operable to clip a voltage level at the output node to be equal to or lower than a level of a first reference voltage and a second clipping unit operable to clip a voltage level at the output node to be equal to or greater than a level of a second reference voltage, wherein the second reference voltage is lower than the first reference voltage. A predetermined level of a voltage is outputted through an output unit included in the variable gain amplifier based on the clipped voltage level.