Pseudo Differential Amplifier Bias Control for Even-Order Distortion
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Solution Overview
Problem
In pseudo differential type power amplifiers, even number-order distortion is difficult to remove due to mismatches in single-phase circuitries amplifying differential input signals, leading to output signal distortion.
Innovation Solution
An amplifier circuitry comprising a first and second amplifier, a voltage generating circuitry, and a control circuitry that adjusts bias voltages to minimize the difference between the DC components of the outputs from both amplifiers, thereby reducing second-order distortion by using a balun, capacitors, resistors, and a comparator circuit to control the bias voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pseudo differential type power amplifier is used, then even number-order distortion is ideally canceled at output, but mismatch in single-phase circuitries causes even number-order distortion to remain
Solution Approach 1:
The patent employs a feedback mechanism where the DC components of the output signals from both amplifiers are detected and fed back to the bias voltage generation circuitry. This feedback loop allows the system to automatically adjust the bias voltages to minimize the difference between the DC components, thereby compensating for mismatches in the single-phase circuitries and reducing even number-order distortion.
Solution Approach 2:
The patent dynamically adjusts the bias voltage parameters applied to each amplifier based on the detected DC component difference. By changing the bias voltage parameters in response to the mismatch conditions, the system optimizes the operating points of the amplifiers to minimize distortion while maintaining the benefits of the pseudo differential configuration.
2Object-affected harmful factors
If bias voltage is applied to minimize DC component difference, then second-order distortion is reduced, but additional circuitry is required
Solution Approach 1:
The bias voltage generation circuitry serves multiple functions: it provides the necessary bias voltages for amplifier operation and simultaneously acts as a correction mechanism by adjusting these voltages based on feedback from the DC component detection. This multi-functionality reduces the need for separate correction circuits, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent introduces intermediary components such as the DC component detection circuitry and the voltage correction circuitry that mediate between the amplifiers and the bias voltage sources. These intermediaries enable automatic adjustment of bias voltages to minimize distortion without requiring complex manual calibration or additional active control elements.
Data Source
AI summary
An amplifier circuitry includes a first amplifier, a second amplifier, a voltage generating circuitry, and a control circuitry. The first amplifier circuitry configured to amplify a first signal. The second amplifier circuitry configured to amplify a second signal which forms differential signals together with the first signal. The voltage generating circuitry configured to generate at least one of a first bias voltage to be applied to the first signal and a second bias voltage to be applied to the second signal. The control circuitry configured to control the voltage generation circuitry so as to decrease a difference between a DC component of an output of the first amplifier circuitry and a DC component of an output of the second amplifier circuitry.