De-Gain Amplifier Architecture for High-Frequency Class-AB Efficiency
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Solution Overview
Problem
Conventional class-AB amplifiers suffer from efficiency losses due to capacitive coupling between driving signals, causing both PMOS and NMOS to be enabled simultaneously, which reduces efficiency, especially at high frequencies, making them behave like class-A amplifiers.
Innovation Solution
The design incorporates a de-gain stage with a low-pass filter and control circuit to provide different path gain control for the P-side and N-side paths, stabilizing the driving signals by filtering and generating control signals to limit signal swings, preventing unwanted current draw and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional class-AB amplifier architecture is used, then the amplifier can operate at high frequency, but the efficiency deteriorates due to simultaneous enablement of PMOS and NMOS caused by capacitive coupling
Solution Approach 1:
A de-gain stage is introduced as an intermediary between the amplifier stage and power stage. This stage includes a first control circuit that receives the second driving signal and generates a first control signal to limit the swing of the first driving signal, preventing simultaneous enablement of PMOS and NMOS while maintaining high-frequency operation capability
Solution Approach 2:
The de-gain stage dynamically adjusts the gain parameter of the first driving signal based on the second driving signal. By changing the signal swing parameter through the control circuit, the system prevents both transistors from being enabled simultaneously while preserving the ability to operate at high frequencies
2Loss of information
If capacitor coupling is used between stages, then signal transmission is achieved, but harmful capacitive coupling effect causes both PMOS and NMOS to be enabled simultaneously
Solution Approach 1:
The harmful capacitive coupling effect is extracted and addressed separately through the de-gain stage. The control circuit specifically processes the second driving signal to generate a control signal that counteracts the harmful coupling effect, allowing signal transmission while eliminating the leakage current problem
Solution Approach 2:
The de-gain stage converts the potentially harmful capacitive coupling effect into a beneficial control mechanism. By using the second driving signal (which causes the harmful effect) as the input to the control circuit, the system generates a compensating control signal that prevents simultaneous transistor enablement, turning the harmful coupling into a useful control relationship
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 effectively stabilizes the driving signals, preventing simultaneous enablement of PMOS and NMOS, thereby enhancing the amplifier's efficiency and reducing its operation to behave more like a class-AB amplifier even at high frequencies.
Implementation Method 1
The de-gain stage comprises a low-pass filter and a control circuit, wherein the low-pass filter is configured to filter the second driving signal to generate a filtered control signal
Data Source
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AI summary
The present invention provides an amplifier including an input stage, an amplifier stage, a power stage and a de-gain stage. The input stage is configured to receive an input signal to generate an amplified signal. The amplifier stage is configured to generate a first driving signal and a second driving signal according to the amplified signal. The power stage comprises a first input terminal and a second input terminal, wherein the power stage is coupled to a supply voltage and a ground voltage, for receiving the first driving signal and the second driving signal from the first input terminal and the second input terminal, respectively, and generating an output signal.