Optical Reception Circuit With Reference-Voltage Offset Compensation
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Solution Overview
Problem
Existing reception circuits for optical communication struggle to effectively compensate for offsets in differential voltage signals, leading to reduced accuracy and increased noise, especially when the average voltage value of the input current changes.
Innovation Solution
The proposed reception circuit includes an input terminal for receiving an input current, a voltage signal circuit for converting the current signal into a voltage signal, a reference voltage circuit for generating a reference voltage, a differential amplifier circuit for generating a differential signal, and an offset control circuit that adjusts feedback currents to maintain the offset of the differential signal within a tolerance, regardless of the average voltage value of the input current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional automatic offset control circuit draws a portion of the input current to compensate for offset, then the offset of the differential voltage signal can be reduced, but the accuracy deteriorates when the average voltage value of the input current changes
Solution Approach 1:
The patent introduces a reference voltage circuit as an intermediary element that generates a reference voltage based on the input current. The differential amplifier then compares the voltage signal with this reference voltage to generate the differential output signal. This intermediary reference voltage mechanism enables accurate offset compensation that remains stable even when the average voltage value of the input current changes, resolving the contradiction between offset reduction accuracy and compensation stability.
2Measurement precision
If the offset control circuit adjusts feedback current to compensate for offset, then the differential signal offset is reduced, but noise increases due to current extraction from input signal
Solution Approach 1:
The patent segments the offset compensation function into two independent parts: (1) a reference voltage circuit that generates reference voltage based on the input current, and (2) a differential amplifier that subtracts the reference voltage from the voltage signal. This segmentation allows offset compensation without extracting current from the input signal path, thereby reducing differential signal offset accuracy while minimizing noise generation.
3Device complexity
If a simple voltage-to-current conversion circuit is used, then device complexity is reduced, but manufacturing precision deteriorates due to inability to maintain offset tolerance under varying input conditions
Solution Approach 1:
The patent implements a feedback mechanism where the reference voltage circuit continuously generates a reference voltage based on the input current, and the differential amplifier continuously compares this reference voltage with the voltage signal. This feedback loop ensures that the offset of the differential signal remains within tolerance even when input conditions vary, achieving manufacturing precision without excessive complexity.
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
This solution effectively reduces the offset of the differential signal to within a tolerance, improving the accuracy and reducing noise in the reception circuit, even when the average voltage value of the input current varies.
Implementation Method 1
A reception circuit for optical communication receives a current signal converted from an optical signal by a photodiode or the like as an input current
Implementation Method 2
a voltage signal circuit having an input node, the voltage signal circuit being configured to convert a current signal into a voltage signal
Data Source
AI summary
A reception circuit includes an input terminal configured to receive an input current; a voltage signal circuit being configured to convert a current signal into a voltage signal; a reference voltage circuit configured to generate a reference voltage in accordance with a first feedback current; a differential amplifier circuit configured to generate a differential signal in accordance with a voltage difference between the voltage signal and the reference voltage; and an offset control circuit configured to generate the first feedback current and a second feedback current, adjust the first feedback current when the voltage signal has an average voltage value greater than the reference voltage, and subtract the second feedback current from the input current such that the offset of the differential signal falls within the tolerance when the voltage signal has an average voltage value smaller than the reference voltage.