DC Offset Cancellation Circuit With Pre-Charged Gate Control
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Solution Overview
Problem
Conventional methods for canceling direct current offset current in optical communication systems are slow and inefficient, leading to distorted voltage signals due to the slow turn-on speed of field effect transistors, which affects the accuracy and stability of the voltage signal output by amplifiers.
Innovation Solution
A direct current offset current cancellation circuit comprising an optical detection module, first amplification module, first filtering module, acceleration module, charging module, and direct current cancellation module, where the acceleration module rapidly charges the charging module to provide a cancellation voltage correlated with the direct current offset voltage, enabling quick and accurate cancellation of the offset current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an offset voltage is extracted from a voltage signal and applied to a gate of a field effect transistor to cancel direct current offset current, then the offset current cancellation is achieved, but the turn-on speed of the field effect transistor is slow and the extraction speed of the offset current is slow
Solution Approach 1:
The patent applies preliminary action by pre-charging a capacitor with the offset voltage before it is needed for cancellation. The capacitor is charged in advance during periods when the offset voltage is stable, so that when cancellation is required, the pre-charged capacitor can immediately provide the necessary voltage to the field effect transistor gate, eliminating the slow turn-on delay
Solution Approach 2:
The patent implements dynamics by using a switchable circuit configuration that can operate in different modes. The circuit dynamically switches between a charging mode (where the capacitor is being charged from the voltage signal) and a cancellation mode (where the pre-charged capacitor provides voltage to the field effect transistor), optimizing performance for each operational state
2Reliability
If the offset voltage is slowly increased from zero to the offset voltage, then the field effect transistor turns on gradually, but this results in slow extraction speed of the direct current offset current
Solution Approach 1:
The capacitor is charged in advance to the required offset voltage level before cancellation operation begins. This preliminary charging action stores the necessary energy in the capacitor, enabling immediate high-speed cancellation when needed, rather than gradually building up the voltage
Solution Approach 2:
The patent creates a copy of the offset voltage in the form of a pre-charged capacitor. Instead of directly applying and slowly increasing the offset voltage from the voltage signal, the circuit creates a replicated voltage source in the capacitor that can be instantly applied to the field effect transistor gate
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
The proposed circuit accelerates the charging rate of the charging module, allowing for rapid and precise cancellation of direct current offset current, thereby stabilizing and enhancing the accuracy of the voltage signal output by the amplifier.
Implementation Method 1
an optical detector converts an optical signal into a current signal
Implementation Method 2
The charging module comprises a capacitor connected between the second end of the direct current cancellation module and ground
Data Source
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AI summary
Embodiments of this application disclose a direct current offset current cancellation circuit and method, and a related device, to improve accuracy and a speed of canceling a direct current offset current. An optical detection module included in the cancellation circuit in this application is configured to output a current signal. A first amplification module is configured to convert and amplify the current signal into a voltage signal. A first filtering module is configured to filter the voltage signal to obtain a direct current offset voltage. An acceleration module is configured to provide a target voltage for a charging module. The charging module is configured to output a cancellation voltage based on the target voltage and the direct current offset voltage. A direct current cancellation module is configured to cancel a direct current offset current in the current signal based on the cancellation voltage.