Optical Receiving Circuit Temperature Compensation
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Solution Overview
Problem
Optical receivers in optically coupled and transmission devices face challenges in reducing temperature dependency of transmission delay time and input sensitivity, as existing technologies do not sufficiently mitigate the effects of temperature changes on these parameters.
Innovation Solution
The optical-receiving circuit incorporates a first photodiode, a trans-impedance amplifier with a negative feedback resistor, and an output circuit with a temperature-controlled voltage source, utilizing a polysilicon resistance and PTAT/CTAT current sources to manage temperature coefficients and reduce transmission delay time and input sensitivity fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical receiver components are used, then the device can perform basic optical signal reception, but the transmission delay time and input sensitivity show significant temperature dependency
Solution Approach 1:
The patent applies parameter changes by carefully selecting the temperature coefficient of the power supply voltage Vreg to be positive, which compensates for the negative temperature coefficient of Vbe. This parameter selection ensures that the cutoff frequency fc remains stable across temperature variations, thereby maintaining consistent transmission delay time and input sensitivity without requiring complex additional circuits.
Solution Approach 2:
The patent creates an equipotential condition by designing the power supply voltage Vreg to have a temperature coefficient that exactly compensates for the temperature drift of Vbe. This balancing approach ensures that the critical voltage parameter (Vreg - M×Vbe) remains constant with temperature, achieving temperature-independent operation of the trans-impedance amplifier while keeping the circuit structure relatively simple.
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 configuration effectively reduces temperature dependency of the cutoff frequency, transmission delay time, and input sensitivity, enabling stable high-speed data transmission across a wide temperature range.
Implementation Method 1
a first photodiode converting an optical signal into a current signal
Data Source
AI summary
An optical-receiving circuit includes a first photodiode converting an optical signal into a current signal, a first trans-impedance amplifier to which a first power supply voltage of Vreg is supplied and which has a negative feedback resistor and to which the current signal is input and which outputs a voltage signal, and an output circuit to which the voltage signal output from the first trans-impedance amplifier is input and which outputs a voltage signal to the outside. A temperature coefficient of a voltage of (Vreg−MVbe) is positive, in which Vbe is a base-emitter voltage of a transistor contained in the first trans-impedance amplifier and M is a coefficient that does not depend on the temperature.