Pipelined ADC Stage Layout With Uniform Op-Amp Gain Correction
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Solution Overview
Problem
Conventional pipelined AD converters face difficulties in layout design and gain error measurement, requiring time and labor, and struggle to improve linearity and S/N ratio due to varying op-amp gains across stages.
Innovation Solution
A pipelined AD converter design with cascaded stages featuring op-amps of the same configuration connected in parallel, allowing for easy layout design and gain error determination, along with digital correction circuits to adjust current drive capability and capacitance values, ensuring uniform gain across stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If op-amps are designed with different gain and current drive capability for each conversion stage, then amplification precision is optimized for each stage, but layout design becomes difficult and the number of design man-hours increases
Solution Approach 1:
The patent changes the parameter of op-amp configuration from stage-specific customization to uniform configuration across all stages. By using the same op-amp design for every conversion stage, the layout design process is simplified significantly, reducing design complexity and man-hours while maintaining acceptable amplification precision through digital correction techniques.
2Measurement precision
If gain errors of op-amps are measured individually for each conversion stage, then accurate digital correction can be applied, but measurement time and labor increase significantly
Solution Approach 1:
The patent changes the measurement approach from individual stage measurement to measurement of a single representative stage. Since all op-amps have the same configuration, measuring the gain error of one op-amp provides information about all others, dramatically reducing measurement time and labor while maintaining sufficient accuracy for digital correction.
3Manufacturing precision
If different gain values are used in different conversion stages, then each stage can be optimized for its specific requirements, but the linearity of input/output characteristic deteriorates and S/N ratio improvement becomes difficult
Solution Approach 1:
The patent changes the gain parameter from stage-specific variation to uniform value across all stages. This uniform gain configuration improves the linearity of the input/output characteristic and enables effective S/N ratio improvement through digital correction, while stage-specific optimization requirements are met through software-based correction algorithms.
4Manufacturing precision
If capacitor values and op-amp specifications are optimized for each conversion stage, then performance is maximized, but circuit scale and power consumption increase
Solution Approach 1:
The patent changes the component specification approach from stage-specific optimization to uniform specifications across all stages. By using the same capacitor values and op-amp specifications for every stage, the overall circuit scale is reduced and power consumption is lowered, while performance requirements are still met through digital correction techniques.
Data Source
AI summary
A pipelined AD converter (1) includes a plurality of conversion stages (11, 11, . . . ). In each of the conversion stages, an analog-to-digital conversion circuit (101) converts an input voltage (Vin) from the preceding stage to a digital code (Dout). A digital-to-analog conversion circuit (102) converts the digital code obtained by the analog-to-digital conversion circuit to an intermediate voltage (Vda). A charge operation circuit (103) has: a capacitor section (C1, C2) for sampling the input voltage; and an amplifier section (104) for amplifying a mixed voltage of the input voltage sampled by the capacitor section and the intermediate voltage obtained by the digital-to-analog conversion circuit. The amplifier section (104) includes a plurality of op-amps (amp1, amp1, . . . ) having the same configuration and connected in parallel with each other.