Stabilizing Reference Voltage in Switched Capacitor Circuits
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Solution Overview
Problem
Switched capacitor circuits in analog-to-digital converters (ADCs) face instability in reference voltage due to code-dependent load currents, leading to voltage fluctuations that degrade linearity and accuracy.
Innovation Solution
A stabilizing circuit is introduced to manage the reference voltage by supplying or drawing a stabilizing charge based on the states of the switched capacitor circuit, making the sum of switched capacitor and stabilizing charges independent of these states, and using a feedback circuit and buffer to compensate for errors and replenish depleted charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switched capacitor circuits are used in ADCs, then data conversion functionality is achieved, but reference voltage instability occurs due to code-dependent load currents
Solution Approach 1:
A feedback circuit is introduced that monitors the reference voltage at the reference node and provides feedback signals to control switches. This feedback mechanism detects voltage deviations caused by code-dependent load currents and adjusts the switched capacitor circuit operation to maintain stable reference voltage, thereby resolving the contradiction between achieving data conversion functionality and maintaining reference voltage stability.
Solution Approach 2:
An intermediate control circuit is introduced between the switched capacitor circuit and the reference voltage source. This intermediary circuit manages the code-dependent load currents by controlling switch operations based on feedback signals, preventing direct voltage fluctuations from affecting the reference node while still enabling data conversion functionality.
2Productivity
If code-dependent load current is drawn from reference voltage, then ADC conversion operation is enabled, but voltage fluctuations occur that degrade linearity and accuracy
Solution Approach 1:
The feedback circuit monitors reference voltage and generates control signals that adjust the switched capacitor circuit operation in real-time. This feedback control compensates for voltage fluctuations caused by code-dependent load currents, maintaining both ADC conversion operation and measurement precision by preventing linearity and accuracy degradation.
Solution Approach 2:
The system dynamically changes operating parameters (switch control signals) based on feedback from the reference voltage monitoring circuit. By adjusting switch timing and capacitance configuration in response to detected voltage variations, the system maintains accurate linear operation while enabling continuous ADC conversion productivity.
3Stability of the object's composition
If stabilizing circuit is added to manage reference voltage, then reference voltage stability is improved, but device complexity increases
Solution Approach 1:
A feedback circuit is introduced that monitors the reference voltage at the reference node and provides feedback signals to control switches. This feedback mechanism detects voltage deviations caused by code-dependent load currents and adjusts the switched capacitor circuit operation to maintain stable reference voltage, thereby resolving the contradiction between achieving data conversion functionality and maintaining reference voltage stability.
Solution Approach 2:
The stabilizing circuit is designed to perform multiple functions: monitoring reference voltage, generating feedback control signals, and adjusting switched capacitor operations. By making the stabilizing circuit multi-functional, the patent reduces overall system complexity while achieving reference voltage stability, as one integrated circuit performs what would otherwise require multiple separate components.
Data Source
AI summary
A system includes a switched capacitor circuit and a stabilizing circuit. The switched capacitor circuit receives a reference voltage from a reference node, transitions from a first state to a second state, and draws or supplies a switched capacitor charge from or to the reference node in response to transitioning from the first state to the second state. The second state is a function of the first state, an input of the switched capacitor circuit, or a combination of both. The stabilizing circuit stabilizes the reference voltage by supplying or drawing a stabilizing charge to or from the reference node based on the first and second states of the switched capacitor circuit.