Sampled-Data Reference Circuits With Level-Crossing Switch Control
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Solution Overview
Problem
In sampled-data analog circuits, operational amplifiers face challenges in providing sufficient open-loop gain, low noise, and fast settling times, especially with low power supply voltages and device gain limitations, which affect the accuracy and efficiency of signal integration and voltage reference applications.
Innovation Solution
The implementation of zero-crossing detectors and voltage reference circuits that utilize level-crossing detection signals to control sampling switches and waveform generators, reducing power consumption while maintaining noise performance and speed in switched-capacitor circuits and analog-to-digital converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If operational amplifiers are used to provide sufficient open-loop gain and fast settling time in sampled-data circuits, then signal integration accuracy is improved, but power consumption increases and device gain limitations are exacerbated
Solution Approach 1:
The patent extracts the voltage reference generation function from the operational amplifier and implements it separately using switched-capacitor circuits with level-crossing detection. This separation allows the operational amplifier to focus on signal processing while the dedicated reference circuit provides accurate voltage references with lower power consumption.
Solution Approach 2:
The patent employs periodic switching of capacitors in the voltage reference circuit, where capacitors are charged during one phase and discharged during another phase. This periodic action enables the circuit to maintain accurate voltage references through time-averaged operation, reducing the continuous power consumption requirements.
2Speed
If operational amplifiers are designed for fast settling time, then sampling speed is improved, but power consumption and device gain limitations worsen
Solution Approach 1:
The patent implements dynamic voltage reference generation using switched-capacitor circuits that adapt their operation to the sampling phase. The circuit dynamically switches between charging and discharging modes, enabling fast response to sampling events without requiring continuous high-power operation.
Solution Approach 2:
The patent changes the operational parameters of the voltage reference circuit by using time-varying capacitor switching patterns. This allows the circuit to achieve fast settling when needed (during sampling phases) while consuming less power during non-critical periods, effectively decoupling speed requirements from continuous power consumption.
3Stability of the object's composition
If voltage reference circuits operate continuously to maintain accuracy, then reference voltage stability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic switching of capacitors in the voltage reference circuit, where capacitors are charged during one phase and discharged during another phase. This periodic action enables the circuit to maintain accurate voltage references through time-averaged operation, reducing the continuous power consumption requirements.
Solution Approach 2:
The patent ensures continuous useful action by maintaining the voltage reference availability through carefully timed capacitor charging and discharging cycles. The switched-capacitor network ensures that the reference voltage remains stable and available throughout the sampling process without requiring continuous high-power operation.
Data Source
AI summary
A switched capacitor circuit includes a first level-crossing detector to generate a level-crossing detection signal when an input signal crosses a first predetermined level. A first waveform generator generates a first predetermined waveform and a second waveform generator generates a second predetermined waveform. A second level-crossing detector generates a second level-crossing detection signal when said second predetermined waveform crosses a voltage reference level a second time. A second switch is coupled to the second level-crossing detector, and a third switch is coupled to the first level-crossing detector. The second switch turns OFF when the second level-crossing detection signal indicates the second predetermined waveform crossed the voltage reference level a second time. The third switch turns OFF when the first level-crossing detection signal indicates the input signal crossed the first predetermined level.