Optical Receiver Circuit Damping for Preamplifier Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical receiver circuits face challenges in suppressing oscillation in preamplifiers due to resonance peaks caused by inductance in the RLC resonance circuit, particularly in high-frequency ranges, as the existing techniques for reducing wiring length and parasitic inductance are limited by manufacturing constraints.
Innovation Solution
Incorporating a resistive element on the submount substrate between the bias voltage wiring and the cathode pad of the light receiving element, with a resistance value determined to suppress the resonance peak and prevent oscillation in the preamplifier, thereby reducing the influence of inductance in the RLC resonance circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wiring length is reduced to decrease parasitic inductance, then oscillation suppression improves, but manufacturing complexity increases due to additional constraints
Solution Approach 1:
A damping resistor is introduced as an intermediary element between the light receiving element and the preamplifier. This resistor serves as a mediator that suppresses oscillation by reducing the Q value of the RLC resonance circuit, thereby decreasing parasitic inductance effects without requiring complex manufacturing processes or wiring length reductions.
2Reliability
If decoupling capacitors are added to suppress resonance peaks, then oscillation suppression improves, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for additional decoupling capacitors by incorporating a damping resistor directly into the existing circuit path. This removes the requirement for separate resonance suppression components, thereby reducing device complexity while maintaining oscillation suppression effectiveness.
3Power
If preamplifier gain is increased to improve signal amplification, then signal strength improves, but oscillation tendency increases due to phase difference reaching 180°
Solution Approach 1:
A damping resistor is incorporated beforehand into the circuit to reduce the Q value of the RLC resonance circuit. This prior cushioning measure suppresses resonance peaks and prevents phase difference from reaching 180°, thereby allowing the preamplifier to operate at higher gain levels without inducing oscillation.
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 approach effectively suppresses oscillation in the preamplifier without additional manufacturing constraints, improving manufacturing yield and eliminating the need for extra components like decoupling capacitors, while maintaining a compact footprint.
Implementation Method 1
the optical receiver circuit can be regarded as one RLC resonance circuit when represented by an equivalent circuit and viewed from the side of the input terminal of the preamplifier, and a resonance peak occurs at a specific frequency
Implementation Method 2
A resistance value of the first resistive element is determined such that a resonance peak between the preamplifier and ground is suppressed
Data Source
AI summary
An optical receiver circuit includes a light receiving element to convert an optical signal into a current signal, a submount substrate on which the light receiving element is mounted, a wiring connected to an anode pad of the light receiving element and a wire connected to a preamplifier on the submount substrate, a wiring to which a bias voltage is applied on the submount substrate; a wiring connected to a cathode pad of the light receiving element on the submount substrate; and a resistor connected to the wiring to serve as a path when the bias voltage is applied to the light receiving element via the wiring on the submount substrate. A resistance value of the resistor is determined such that a resonance peak between the preamplifier and ground is suppressed and that oscillation in the preamplifier is suppressed.