Optical Signal Receiving Circuit for ADC-Matched Differential Output
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Solution Overview
Problem
Optical sensing apparatuses face challenges in converting photocurrent signals into differential voltage signals that match the input requirements of analog-to-digital converters (ADCs) to avoid signal distortion.
Innovation Solution
The optical signal receiving circuit includes a transimpedance amplifier and a single-ended-to-differential converter, along with adjustment circuits and level shifters, to convert photocurrent signals into differential voltage signals with matching DC voltages for ADC input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple transimpedance amplifier is used to convert photocurrent to voltage, then the conversion process is simple, but the output voltage signal does not match the DC input requirements of ADCs causing signal distortion
Solution Approach 1:
The optical signal receiving circuit is divided into three functional modules: a transimpedance amplifier for current-to-voltage conversion, an adjustment circuit for DC voltage level adjustment, and a single-ended-to-differential converter for signal format conversion. This segmentation allows each module to perform its specific function optimally, ensuring the final output matches ADC requirements while maintaining overall system manageability.
Solution Approach 2:
The adjustment circuit acts as an intermediary between the transimpedance amplifier and the single-ended-to-differential converter. It receives the first voltage signal from the amplifier, adjusts its DC voltage level using level shifters, and provides the adjusted signal to the converter, thereby mediating the voltage level mismatch issue.
2Reliability
If voltage level adjustment circuits and level shifters are added to match ADC input requirements, then signal quality is improved, but device complexity increases
Solution Approach 1:
The adjustment circuit combines multiple level shifter circuits into a unified module that receives a single input signal and generates properly level-adjusted output signals. This merging approach reduces the need for separate adjustment circuits for each signal path, thereby limiting the increase in overall device complexity while still achieving the necessary voltage level matching.
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 ensures that the differential voltage signals generated by the optical signal receiving circuit have DC voltages that match the ADC inputs, preventing signal distortion and maintaining signal quality.
Implementation Method 1
an optoelectronic detector configured to generate a photocurrent signal in response to an optical signal
Implementation Method 2
a transimpedance amplifier coupled to the optoelectronic detector and configured to convert the photocurrent signal from the optoelectronic detector into a first voltage signal
Data Source
AI summary
An optical sensing apparatus includes an optical signal receiving circuit configured to receive a photocurrent signal from an optoelectronic detector and generate a differential voltage signal. The optical signal receiving circuit includes a transimpedance amplifier coupled to the optoelectronic detector and configured to convert the photocurrent signal from the optoelectronic detector into a first voltage signal. The optical signal receiving circuit includes a first power source configured to provide a first bias voltage for the optoelectronic detector. The optical signal receiving circuit includes an adjustment circuit coupled to the transimpedance amplifier and configured to adjust the first voltage signal to generate a second voltage signal. The optical signal receiving circuit includes a single-ended-to-differential converter coupled to the adjustment circuit and configured to convert the second voltage signal into the differential voltage signal.