MOS Envelope Detector Feedback Biasing for Wider Dynamic Range
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Solution Overview
Problem
Conventional electronic envelope detection circuits face challenges in dynamically adapting their biasing point and conversion gain to variations in the average power of radiofrequency input signals, leading to limited dynamic range and signal distortion, especially in wireless communication applications.
Innovation Solution
An electronic envelope detection circuit with a MOS transistor-based input signal detecting circuit and a processing circuit that dynamically regulates the biasing point using a control signal, allowing the circuit to adapt to changes in input signal power, featuring a transformer configuration that applies the input and control signals to the transistors' gates and sources to control the biasing point and enhance conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional envelope detector with a fixed biasing point amplifier is used, then the circuit structure is simple, but the dynamic range is limited and signal distortion occurs when input signal power varies
Solution Approach 1:
The patent implements dynamic biasing point adjustment by introducing a control signal that varies the gate voltage of the MOS transistor based on the average power of the input signal. This transforms the previously fixed biasing point into a dynamic parameter that adapts to input signal conditions, thereby extending the dynamic range and preventing signal distortion while maintaining reasonable circuit complexity.
2Measurement precision
If the biasing point is configured for maximum conversion gain, then sensitivity is maximized, but the dynamic range is reduced
Solution Approach 1:
The patent resolves this contradiction by making the biasing point dynamic rather than fixed. The control signal adjusts the gate voltage to maintain optimal conversion gain across varying input signal power levels, allowing the circuit to adapt between maximum sensitivity and extended dynamic range based on real-time input conditions.
Solution Approach 2:
The patent changes the biasing point parameter dynamically based on input signal power. By varying the gate voltage of the MOS transistor through the control signal, the circuit adjusts its operating parameters to optimize performance across different input power levels, resolving the trade-off between conversion gain and dynamic range.
3Adaptability or versatility
If feedback circuit is added to adapt biasing point dynamically, then dynamic range is extended, but circuit complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the average power of the input signal is detected and used to generate a control signal that adjusts the biasing point. This feedback loop enables dynamic range extension by automatically adapting the biasing point to input signal conditions while maintaining manageable circuit complexity through efficient feedback implementation.
Data Source
AI summary
An electronic envelope detection circuit includes an input signal detecting circuit having at least one MOS transistor configured to receive a radiofrequency input signal and to deliver an internal signal on the basis of the input signal. The biasing point of the at least one transistor is controlled by the input signal and a control signal. A processing circuit that is coupled to the input signal detecting circuit is configured to deliver a low-frequency output signal on the basis of the internal signal and further deliver the control signal on the basis of the output signal. In operation, the value of the control signal decreases when the average power of the input signal increases, and vice versa.