Light Sensor Circuit Design to Reduce Dark Current and Capacitance
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Summary
Problems
Existing light sensor circuits face issues with junction capacitance and dark current in photodiodes, affecting the accuracy and linearity of sensor measurements, particularly in analog-to-digital converters.
Innovation solutions
A light sensor circuit design that maintains the cathode voltage of a photodiode at the same level as the anode, effectively reducing apparent junction capacitance and dark current influence by using a first and second amplifier, an active load, and switches to control the integration process without requiring a capacitor.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a conventional integrating unit operating under a reference voltage VCM is used, then the circuit can function as an analog-to-digital converter, but the junction capacitance of the photodiode cannot be reduced and dark current affects measurement accuracy
Why choose this principle:
The patent changes the operating voltage parameter from a fixed reference voltage VCM to a dynamically controlled voltage that tracks the anode voltage. By making the cathode voltage track the anode voltage through the amplifier circuit, the voltage difference across the photodiode junction is minimized, effectively reducing the apparent junction capacitance and dark current effects without requiring additional capacitors.
Principle concept:
If a conventional integrating unit operating under a reference voltage VCM is used, then the circuit can function as an analog-to-digital converter, but the junction capacitance of the photodiode cannot be reduced and dark current affects measurement accuracy
Why choose this principle:
The patent replaces the traditional capacitor-based voltage holding mechanism with an amplifier-based voltage tracking system. Instead of using a capacitor to maintain the cathode voltage at a fixed reference level, the invention uses an amplifier to actively track and replicate the anode voltage at the cathode, substituting passive energy storage with active voltage control.
Application Domain
Data Source
AI summary:
A light sensor circuit design that maintains the cathode voltage of a photodiode at the same level as the anode, effectively reducing apparent junction capacitance and dark current influence by using a first and second amplifier, an active load, and switches to control the integration process without requiring a capacitor.
Abstract
The present application discloses a light sensor circuit comprising a first amplifier, a second amplifier and an active load. An integration circuit is formed by the operation of this light sensor circuit and connected to a photodiode. The cathode of the photodiode is controlled to maintain an identical or approximate voltage level with the anode of the photodiode, which significantly reduces the influence of the dark current from the photodiode. Consequently, when applied to an analog-to-digital conversion device, the light sensor circuit effectively maintains the performance and accuracy of the device. Additionally, this design significantly reduces circuit complexity and manufacturing costs.