Configurable Pulser Circuit for Harmonic Distortion Trimming
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Solution Overview
Problem
Ultrasound machine pulser amplifiers face challenges in maintaining compliance with second harmonic distortion criteria due to variations in supply and handle potentials, affecting the accuracy of the machine's performance.
Innovation Solution
A semiconductor device with a high side and low side transistor configuration, utilizing trim storage and an encoder to determine and adjust the number of selectable transistor units based on measured saturation currents and source-to-handle voltages, ensuring matching rise and fall times to meet the distortion criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of transistor units is fixed, then the device structure is simple, but the second harmonic distortion specification cannot be met across varying supply voltages
Solution Approach 1:
The transistor is divided into multiple selectable units (first transistor units for high side, second transistor units for low side) that can be independently configured. This segmentation allows the system to adjust the effective number of transistor units based on supply voltage conditions, enabling compliance with second harmonic distortion specifications across varying voltage ranges while managing device complexity through modular configuration.
Solution Approach 2:
The system dynamically adjusts the number of active transistor units based on measured supply voltage and handle voltage. The encoder determines target numbers of transistor units to select, and gate drivers configure the appropriate number of units in real-time. This dynamic adaptation ensures that the transmitter meets distortion specifications under different operating conditions without requiring a completely different device design.
2Measurement precision
If trim values are stored and used, then the transmitter can be accurately trimmed across voltage ranges, but additional memory and control circuitry are required
Solution Approach 1:
Trim values are pre-calculated and stored in trim storage during manufacturing or initialization, based on expected supply voltage ranges. The encoder retrieves appropriate trim values and uses them to determine the target number of transistor units to select. This preliminary preparation allows accurate voltage compensation without requiring complex real-time calculations during operation, balancing measurement precision with acceptable control circuitry complexity.
Solution Approach 2:
The system performs self-configuration by automatically measuring supply voltage and handle voltage, determining the appropriate number of transistor units to activate, and configuring itself without external intervention. The encoder and gate drivers work together to autonomously adjust the transistor unit configuration based on measured conditions, reducing the need for external calibration equipment or complex manual control circuits.
Data Source
AI summary
A semiconductor device includes a trim storage and an encoder. The trim storage stores trim values. The encoder determines a magnitude of a supply voltage, determines a magnitude of a handle voltage, determines a source-to-handle voltage of a first transistor, and determines a source-to-handle voltage of a second transistor. Further, the encoder determines a target number of selectable first transistor units comprising the first transistor to select for the first transistor. Based on a trim value from the trim storage, the source-to-handle voltage of the first transistor and the source-to-handle voltage of the second transistor, the encoder determines a target number of selectable second transistor units comprising the second transistor to select for the second transistor. The encoder asserts control signals to select the target number of selectable first transistor units and the target number of selectable second transistor units.