Diode-less Half-wave Rectifier Circuit for Low-level Signal Detection
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Solution Overview
Problem
Conventional half-wave rectifier circuits using diodes fail to pass low-level signals below the conduction level, limiting their effectiveness in AC to DC conversion and requiring costly AGC circuits in applications like wireless two-way voice systems.
Innovation Solution
A diode-less half-wave rectifier circuit utilizing an operational amplifier with a capacitor and resistors in a negative feedback loop, allowing low-level signals to be converted to half-wave rectified DC signals, thereby extending the dynamic range of rectification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode is used in a conventional half-wave rectifier circuit, then the circuit can block negative portions of AC signals, but low-level signals below the diode conduction level cannot pass through
Solution Approach 1:
The patent removes the diode from the conventional half-wave rectifier circuit, extracting the component that causes the conduction threshold problem. By eliminating the diode, the circuit can now process low-level signals below the typical 0.7V diode drop while maintaining rectification functionality through the operational amplifier-based configuration.
Solution Approach 2:
The patent changes the operating parameters of the rectifier circuit by using an operational amplifier with high gain to replace the diode's nonlinear characteristic. This allows the circuit to maintain rectification behavior for high-level signals while being sensitive enough to detect and rectify low-level signals below the original diode conduction threshold.
2Device complexity
If a diode is used in the half-wave rectifier circuit, then the circuit structure is simple, but costly AGC circuits are required to handle low-level signals
Solution Approach 1:
The operational amplifier-based rectifier circuit performs multiple functions: it rectifies high-level signals like a conventional diode circuit while simultaneously being sensitive to low-level signals, eliminating the need for separate AGC circuitry. This multi-functionality reduces both component count and manufacturing cost.
Solution Approach 2:
The patent merges the rectification function and the low-level signal detection function into a single circuit configuration. The operational amplifier circuit simultaneously provides half-wave rectification for high-level signals and sufficient gain for low-level signals, combining what were previously separate functional requirements.
3Reliability
If a conventional half-wave rectifier is used, then the circuit can provide AC to DC conversion, but the accuracy of VOX detection is reduced for low-level signals
Solution Approach 1:
The patent changes the sensitivity parameters of the detection circuit by using the operational amplifier's high open-loop gain. This allows the circuit to maintain accurate DC voltage representation for VOX detection while being sensitive enough to detect low-level acoustic signals that would otherwise be below the diode conduction threshold.
Data Source
AI summary
A half-wave rectifier including an input port for receiving an incoming AC signal, an output port for outputting a half-wave rectified signal, an operational amplifier including inverting and non-inverting input terminals and an output terminal, the inverting input terminal connected to a ground reference and a non-inverting input terminal coupled to a negative feedback loop and a first resistor. The negative feedback loop including a second resistor coupled between a first node and a second node, the first node coupling the output terminal and the output port and the second node coupling the non-inverting input terminal and the second resistor. A capacitor is coupled to the input port and in series with the first resistor.