Optical Receiver Impedance Switching for Resonance Suppression
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Solution Overview
Problem
Optical receivers face resonance phenomena due to parasitic inductance and capacitance in the circuit, affecting gain bandwidth and frequency response, which existing technologies fail to adequately suppress.
Innovation Solution
An optical receiver design incorporating a transimpedance amplifier circuit with a bypass circuit and a filter circuit, controlled by a control circuit, which adjusts input impedance to mitigate resonance by activating or deactivating the bypass and damping functions based on output voltage, using MOSFETs and field effect transistors to vary resistance and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a bypass circuit is activated to subtract a portion of the current signal, then the linearity of the optical receiver is improved, but the input impedance decreases which may cause resonance phenomenon
Solution Approach 1:
The patent employs dynamic control of the bypass circuit and filter circuit based on the output voltage level. When the output voltage exceeds a threshold, the bypass circuit is activated to improve linearity; when it falls below the threshold, the bypass circuit is deactivated and the filter circuit is activated to suppress resonance. This dynamic switching resolves the contradiction by adapting the circuit configuration to real-time operating conditions.
Solution Approach 2:
The patent changes the input impedance parameter dynamically by switching between different circuit configurations. The bypass circuit decreases input impedance to improve linearity, while the filter circuit increases input impedance to suppress resonance. The control circuit monitors output voltage and switches between these parameter states to maintain optimal performance across different operating ranges.
2Manufacturing precision
If the bypass circuit is activated to improve linearity, then the frequency response characteristics are improved, but the resonance phenomenon is exacerbated due to decreased input impedance
Solution Approach 1:
The control circuit uses feedback from the output voltage to determine the activation state of the bypass and filter circuits. When output voltage indicates good linearity (above threshold), the bypass circuit remains active to maintain frequency response characteristics. When output voltage indicates degraded linearity (below threshold), the control circuit deactivates the bypass circuit and activates the filter circuit to suppress resonance, thus using feedback to resolve the contradiction between frequency response and resonance suppression.
Solution Approach 2:
The system dynamically switches between bypass circuit activation (for improved frequency response) and filter circuit activation (for resonance suppression) based on real-time output voltage monitoring. This dynamic adaptation allows the system to optimize frequency response characteristics when conditions permit while suppressing resonance when necessary, resolving the contradiction through conditional circuit configuration.
3Manufacturing precision
If the input impedance is decreased to improve linearity, then the gain bandwidth is improved, but the resonance phenomenon occurs due to interaction with parasitic inductance and capacitance
Solution Approach 1:
The patent changes the input impedance parameter dynamically by switching between bypass circuit activation (lower impedance for linearity) and filter circuit activation (higher impedance for resonance suppression). The control circuit monitors output voltage and switches between these impedance states, allowing the system to achieve low impedance benefits when conditions permit while preventing resonance through high impedance configuration when necessary.
Solution Approach 2:
The system employs dynamic impedance control through the coordinated switching of bypass and filter circuits. When output voltage indicates acceptable linearity, the bypass circuit maintains lower input impedance to preserve gain bandwidth. When linearity degrades, the control circuit switches to the filter circuit configuration with higher input impedance to suppress resonance, thus dynamically resolving the contradiction between linearity improvement and resonance suppression.
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
Effectively suppresses resonance phenomena, maintaining linearity and improving bandwidth and gain characteristics of the optical receiver, regardless of bypass circuit activation status.
Implementation Method 1
a photodiode receives an optical signal from an external optical waveguide (for example, an optical fiber) and converts the optical signal into a photocurrent
Implementation Method 2
The bypass circuit is configured to decrease a first input impedance of the bypass circuit viewed from the input terminal and subtracts a portion of the current signal from the current signal, when the bypass circuit is activated by a first control signal
Implementation Method 3
The filter circuit is configured to increase a second input impedance of the filter circuit viewed from the bias terminal, when a damping function of the filter circuit is activated by a second control signal
Data Source
AI summary
An optical receiver disclosed includes a bias terminal, an input terminal, a photodiode, an amplifier circuit, a first resistor, a bypass circuit, a filter circuit, and a control circuit. The photodiode receives a bias from the filter circuit through the bias terminal, and outputs a current signal to the amplifier circuit through the input terminal. The amplifier circuit converts an input current to an output voltage. The bypass circuit electrically connected to the input terminal decreases a first input impedance viewed from the input terminal, when activated, and increases the first input impedance, when deactivated. The filter circuit increases a second input impedance viewed from the bias terminal, when a dumping function thereof is activated, and decreases the second input impedance, when the dumping function is deactivated. The control circuit activates the dumping function and the bypass circuit, when the output voltage is larger than a certain voltage.