Comparator-Based Switched-Capacitor Circuit With Linearity Compensation
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Solution Overview
Problem
The linearity of conventional comparator-based switched-capacitor circuits is compromised due to the dependence of the output current on the drain-source voltage of the current source, leading to excessive discharge or charge of the load capacitor, which affects the circuit's performance.
Innovation Solution
A comparator-based switched-capacitor circuit is designed with a compensation circuit that includes multiple capacitors and switches, allowing for the generation and application of voltage differences to offset the fluctuations in current, thereby maintaining the circuit's linearity by balancing the discharge and charge of the load capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional current source is used in the comparator-based SC circuit, then the circuit structure is simple, but the output current is dependent on the drain-source voltage, causing excessive discharge of the load capacitor and decreasing linearity
Solution Approach 1:
The current source is segmented into two independent parts: a digital control terminal that receives digital control signals, and an analog output terminal that provides stable analog current. This segmentation allows the current source to operate independently of drain-source voltage variations, resolving the linearity issue while maintaining structural simplicity.
Solution Approach 2:
A compensation circuit is introduced as an intermediary between the comparator output and the current source. This compensation circuit generates compensation signals that counteract the effects of drain-source voltage variations, thereby improving linearity without requiring a completely complex current source design.
2Reliability
If the output current of the current source is used to control the load capacitor, then the circuit operates as intended, but the current fluctuates with drain-source voltage, causing excessive discharge and affecting performance
Solution Approach 1:
The compensation circuit implements a feedback mechanism by monitoring the comparator output and generating compensation signals that are fed back to the current source. This feedback actively counteracts current fluctuations caused by drain-source voltage changes, ensuring stable and reliable circuit performance.
Solution Approach 2:
The compensation circuit performs preliminary anti-action by generating compensation currents in advance that oppose the harmful discharge effects. When the load capacitor tends to discharge excessively due to current fluctuations, the compensation circuit preemptively applies counteracting current to maintain stable operation.
Data Source
AI summary
A comparator-based switched-capacitor circuit (SC circuit) has a first output terminal and a second output terminal, which output a first output signal and a second output signal, respectively. The comparator-based SC circuit includes a switch-capacitor network, a first current source, a second current source, and a compensation circuit. The first current source is coupled to the switch-capacitor network and the first output terminal. The second current source is coupled to the switch-capacitor network and the second output terminal. The compensation circuit is coupled to the first output terminal and the second output terminal and configured to generate a first and second voltage differences corresponding respectively to the first and second output signals and apply the first and second voltage differences to the second and first output terminals, respectively.