Pseudo Fully-Differential Amplifier With Common-Mode Feedback
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Solution Overview
Problem
Full-differential amplifiers face challenges in maintaining a stable output common-mode level, especially in low-voltage and low-power applications, due to deviations in device matching and power constraints, which limit their operational range and efficiency.
Innovation Solution
An inverse pseudo fully-differential amplifier with a common-mode feedback control circuit, comprising a pseudo fully-differential operation circuit and a common-mode feedback control circuit, which includes inverter amplifiers and capacitors, detects common-mode output voltages to generate feedback control signals, regulating the gains of the inverter amplifiers and stabilizing the output common-mode level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional full-differential amplifier circuits are used, then the amplifier can process signals with strong anti-interference ability, but the output common-mode level becomes unstable due to device matching deviations
Solution Approach 1:
The patent implements a common-mode feedback control circuit that detects the common-mode output voltage and adjusts the gate voltages of the amplifier transistors to maintain a stable common-mode level. This feedback mechanism directly addresses the instability caused by device matching deviations while preserving the differential amplifier's anti-interference capabilities.
Solution Approach 2:
The patent introduces an intermediate common-mode feedback control circuit as a mediator between the differential amplifier stages. This intermediary circuit monitors and regulates the common-mode voltage without interfering with the differential signal processing, thereby stabilizing the common-mode level while maintaining signal integrity.
2Stability of the object's composition
If conventional common-mode feedback circuits are used, then the output common-mode level can be stabilized, but the circuit cannot operate normally at low voltages below 0.8V
Solution Approach 1:
The patent modifies the operating parameters of the feedback control circuit to enable low-voltage operation. By adjusting the threshold voltages and current levels within the feedback circuit, it achieves stable common-mode control at voltages below 0.8V, significantly expanding the operational voltage range compared to conventional circuits.
Solution Approach 2:
The patent employs dynamic biasing techniques where the feedback circuit continuously adapts its operating point based on the input voltage level. This dynamic adjustment allows the circuit to maintain stable common-mode control across a wide voltage range, from low-voltage microbattery applications to higher-voltage environments.
3Use of energy by moving object
If the amplifier operates at low voltage and low power, then power consumption is reduced for microbattery and wireless power supply applications, but the circuit performance and stability deteriorate
Solution Approach 1:
The patent utilizes periodic switching techniques in the feedback control circuit, where capacitors are charged and discharged in controlled cycles to maintain voltage levels. This periodic action reduces average power consumption while ensuring circuit stability, making the amplifier suitable for energy-constrained applications like microbattery and wireless power supply systems.
Solution Approach 2:
The feedback control circuit is designed to self-regulate its power consumption based on operational conditions. It automatically adjusts its activity level and bias currents to maintain stability only when necessary, minimizing power consumption during low-activity periods while ensuring reliability when signal processing is required.
Data Source
AI summary
An inverse pseudo fully-differential amplifier having a common-mode feedback control circuit and a method for maintaining a stable output common-mode level are provided. The inverse pseudo fully-differential amplifier includes the pseudo fully-differential operation circuit and a common-mode feedback control circuit. The pseudo fully-differential operation circuit includes inverter amplifiers (2) and (3). The inverter amplifiers (2) and (3) respectively have a first feedback control terminal and a second feedback control terminal. Input terminals of the common-mode feedback control circuit are respectively connected with output terminals of the inverter amplifier (2) and (3), and are configured to detect common-mode output voltages of the inverter amplifier (2) and (3). An output terminal of the common-mode feedback control circuit is connected with the first feedback control terminal and the second feedback control terminal, and is configured to generate common-mode feedback to the inverter amplifiers (2) and (3) to maintain a stable common mode output level.