MOS Envelope Detection Circuit With Dynamic Bias Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electronic envelope detectors face challenges in maintaining a precise bias point and maximizing conversion gain due to variations in average power of the radio frequency input signal, leading to distortion and limited dynamic range, especially in wireless communication applications.
Innovation Solution
An electronic envelope detection circuit with a detection stage using MOS transistors and a processing stage that dynamically adjusts the gate bias voltage based on the average power of the input signal, utilizing a three-way transformer to control the bias point and enhance conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional envelope detector uses a fixed bias point to maximize conversion gain, then the sensitivity is improved, but the dynamic range is limited and distortion occurs when input signal power varies
Solution Approach 1:
The patent implements dynamic bias point adjustment by introducing a control signal that varies the gate bias voltage of the MOS transistor based on the detected envelope level. This transforms the static biasing system into a dynamic one that adapts to input signal conditions, resolving the contradiction between fixed conversion gain and variable dynamic range requirements
Solution Approach 2:
The invention changes the bias voltage parameter dynamically according to the input signal's envelope power level. By modulating the gate bias voltage in response to signal conditions, the system optimizes conversion gain at each operating point while preventing clipping, thus expanding the effective dynamic range without sacrificing sensitivity
2Adaptability or versatility
If a feedback stage is added to adapt the DC output signal according to average input power, then the dynamic range is extended, but the device complexity increases
Solution Approach 1:
The patent merges the envelope detection function with the automatic gain control function into a single integrated circuit. The same MOS transistor and associated components perform both envelope detection and dynamic bias adjustment, eliminating the need for separate feedback stages and reducing overall circuit complexity while maintaining extended dynamic range capability
Solution Approach 2:
The envelope detector circuit is designed to perform multiple functions simultaneously: it detects the envelope of the input signal, generates a control signal proportional to the envelope power, and uses this control signal to dynamically adjust its own bias point. This multi-functionality reduces the need for additional dedicated components for each function
3Measurement precision
If the bias point is fixed during manufacturing, then the conversion gain is maximized at that point, but variations in input signal power or temperature cause distortion and reduce performance
Solution Approach 1:
The patent implements a feedback mechanism where the detected envelope signal is used to control the bias point of the amplifier. This automatic feedback loop continuously adjusts the operating point to match the current input signal conditions, maintaining optimal conversion gain and preventing distortion across varying signal powers and temperature conditions
Solution Approach 2:
The envelope detector performs self-adjustment by using its own output signal to control its bias point. The circuit automatically adapts to changing conditions without external intervention, maintaining optimal performance through self-regulation of the bias voltage based on real-time signal conditions
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 solution allows for dynamic adaptation of the polarization point and conversion gain, extending the dynamic range of the envelope detector and reducing distortion, enabling efficient signal processing across varying input power levels.
Implementation Method 1
a three-way transformer being for receiving the input signal and for delivering the control signal to the gates of the first and second transistors
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The envelope detection electronic circuit includes a detection stage (7) having at least one MOS transistor (T1, T2, T5, T6, T7) configured to receive a radio frequency input signal (SER) and to deliver an internal signal (SI) from the input signal (SER), the average gate bias voltage of said at least one transistor (T1, T2, T5, T6, T7) being controlled by a control signal (SC), and a processing stage (8) coupled to the detection stage (7) and configured to deliver a low frequency output signal (SSB) from the internal signal (SI) and to deliver the control signal (SC) from the internal signal (SI), such that the value of the control signal (SC) decreases when the average power of the input signal (SER) increases, and vice versa.