Differential ADC Testing Using a Single-Ended DAC and Amplifier
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Solution Overview
Problem
Traditional methods for testing analog-to-digital converters (ADCs) require sophisticated equipment in a factory setting, making it difficult to perform ADC testing within a system or application, especially for higher resolution ADCs that are sensitive to environmental conditions.
Innovation Solution
A method and system that uses a digital-to-analog converter (DAC) to provide test signals to a differential analog-to-digital converter (ADC) through an amplifier stage, allowing for testing within a customer's system by generating differential output voltages based on test codes and determining parameters like integral non-linearity and gain error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional factory-based testing with sophisticated equipment is used, then measurement precision is improved, but device complexity and ease of operation worsen
Solution Approach 1:
The system uses on-chip components (DAC, amplifier, ADC) to perform self-testing without external sophisticated equipment. The DAC generates test signals, the amplifier conditions them, and the ADC converts them back to digital form for evaluation, enabling the system to test itself using existing internal resources.
Solution Approach 2:
The on-chip DAC and amplifier are designed to serve dual purposes: normal operational functions and test signal generation. This multi-functionality eliminates the need for separate dedicated test equipment, reducing overall device complexity while maintaining testing capabilities.
2Measurement precision
If traditional factory-based testing with sophisticated equipment is used, then measurement precision is improved, but ease of operation worsens
Solution Approach 1:
The system enables end-users to perform ADC testing themselves using integrated on-chip components without requiring access to external sophisticated test equipment or specialized factory facilities, dramatically improving ease of operation.
Solution Approach 2:
The on-chip DAC and amplifier act as intermediaries that bridge the gap between available on-chip resources and the need for precise ADC testing. These components transform readily available on-chip signals into appropriate test signals, making precise testing accessible without external equipment.
3Ease of operation
If on-chip components are used for testing, then ease of operation is improved, but measurement precision may worsen
Solution Approach 1:
The amplifier stage serves as a critical intermediary that conditions test signals to achieve full-scale differential voltages at the ADC input. This ensures that even though testing is performed using on-chip components, the measurement precision is maintained by properly scaling and conditioning the test signals.
Solution Approach 2:
The system dynamically adjusts signal parameters (amplitude, differential voltage levels) through the amplifier stage to optimize test signal characteristics. By changing parameters such as gain and voltage levels, the system maintains measurement precision despite using integrated on-chip components.
Data Source
AI summary
A method and circuit for testing an analog-to-digital converter (ADC) are provided. The method comprises: coupling a single-ended output of an analog signal source to a differential input of an amplifier; coupling a differential output of the amplifier to a differential input of the ADC; alternately providing first and second test signals from the single-ended output of the analog signal source to first and second input terminals of the differential input of the amplifier; amplifying the first and second test signals to generate amplified differential signals at the differential output of the amplifier; providing the amplified differential signals to the differential input of the ADC; and determining if an output of the ADC is as expected. An offset may also be provided to the differential output of the amplifier. The method allows an ADC having a differential input to be tested using a digital-to-analog converter (DAC) having a single-ended output.