Optical Receiving Circuit Temperature Compensation
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Solution Overview
Problem
Optical receiving circuits face a decrease in current signal efficiency due to the negative temperature coefficient of photodiodes at high ambient temperatures, leading to deteriorated characteristics such as propagation delay time and input sensitivity.
Innovation Solution
Incorporating a current compensation circuit with a voltage source and current source circuit that generates a positive temperature coefficient current to supplement the photoelectric conversion current of the photodiode, ensuring the current signal remains above a specified threshold even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If photodiode is used for photoelectric conversion, then optical signal can be converted to electrical signal, but current signal decreases at high temperature due to negative temperature coefficient
Solution Approach 1:
The patent applies preliminary anti-action by introducing a compensation current with positive temperature coefficient to counteract the negative temperature coefficient effect on the photodiode current signal. The compensation current is generated in advance through a current source circuit that detects temperature changes and produces an opposing current to maintain stable total current signal output.
2Temperature
If ambient temperature increases, then photodiode generates more thermal noise, but photoelectric conversion efficiency decreases causing current signal to drop
Solution Approach 1:
The patent implements feedback by using a current source circuit that continuously monitors the temperature-dependent current signal from the photodiode and adjusts the compensation current accordingly. The feedback mechanism ensures that as temperature changes affect the photodiode performance, the compensation current is automatically adjusted to maintain stable output signal and input sensitivity.
3Power
If transimpedance circuit converts current signal to voltage, then output voltage is generated, but output voltage decreases when current signal decreases at high temperature
Solution Approach 1:
The patent applies parameter changes by modifying the current signal parameters through temperature compensation. The current source circuit changes the compensation current parameter based on temperature conditions, ensuring that the total current signal (photodiode current + compensation current) remains stable across temperature variations, thereby maintaining stable output voltage from the transimpedance circuit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively stabilizes the current signal level at high temperatures, maintaining the optical receiving circuit's performance across a wide temperature range and preventing decreases in signal amplitude and sensitivity.
Implementation Method 1
a photodiode that photoelectrically converts an optical signal to generate a current signal
Implementation Method 2
The current compensation circuit generates a first current having a positive temperature coefficient
Implementation Method 3
a transimpedance circuit that current-voltage-converts the current signal to generate an output voltage
Data Source
AI summary
According to an embodiment, the optical receiving circuit includes a current compensation circuit, a photodiode, and a transimpedance circuit. The current compensation circuit generates a first current having a positive temperature coefficient. The photodiode receives an optical signal, generates a first current signal including a photoelectric conversion current having a negative temperature coefficient, and outputs a second current signal which is the sum of the first current and the first current signal. The transimpedance circuit has a negative feedback resistor and receives the second current signal and generates an output voltage by current-voltage-converting the second current signal.