Differential Pair Amplifier Gain Control Using Cross-Over Current Feedback
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Solution Overview
Problem
In high-frequency amplifier systems, particularly in wireless communication, the phase variations due to process, voltage, and temperature (PVT) effects cause cross-over currents, leading to power loss and inaccurate gain control, especially in areas with low transmit request levels.
Innovation Solution
An amplifier system comprising a main amplifier, a cross-over current detector, and a controller, where the cross-over current detector identifies the overlapped current from the differential pair, and the controller generates a control signal to adjust the gain based on the output and cross-over current, improving accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is applied to control amplifier gain, then gain control capability is improved, but cross-over current affects accuracy of gain control
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the cross-over current detected by the detector and adjusts the amplifier gain accordingly. The controller generates a control signal based on the detected cross-over current to compensate for its effects, ensuring accurate gain control despite the presence of cross-over current. This closed-loop feedback approach resolves the contradiction by actively counteracting the harmful effect while maintaining control capability.
2Power
If differential pair transistors are used in main amplifier, then amplification capability is improved, but cross-over current is generated causing power loss
Solution Approach 1:
The patent employs a feedback mechanism where the cross-over current detector monitors the actual cross-over current in the differential pair, and the controller adjusts the amplifier operation to minimize power loss. By continuously detecting and compensating for cross-over current, the system maintains the amplification benefits of the differential pair while reducing the associated energy waste.
Solution Approach 2:
The patent converts the harmful cross-over current into a useful signal for control. The cross-over current detector transforms the previously harmful overlapped current into detectable information that the controller uses to optimize amplifier performance. This approach turns the problematic cross-over current into a beneficial control parameter, allowing the system to compensate for and reduce its own power losses.
Data Source
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AI summary
An amplifier system (100) includes a main amplifier (110), a cross-over current detector (120) and a controller (130). The main amplifier (110) includes at least a first driving transistor (MD1) and a second driving transistor (MD2) serving as a differential pair, wherein the first driving transistor (MD1) and the second driving transistor (MD2) are arranged to receive a first input signal and a second input signal, respectively. The cross-over current detector (120) is coupled to the main amplifier (110), and is arranged for detecting a cross-over current of the main amplifier (110), wherein the cross-over current of the main amplifier (110) is an overlapped current from the differential pair. The controller (130) is coupled to the main amplifier (110) and the cross-over current detector (120), and is arranged for generating a control signal to control a gain of the main amplifier (110) according to an output of the main amplifier (110) and the cross-over current of the main amplifier (110).