Amplifier Supply Circuit With Smooth Voltage Tracking
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Solution Overview
Problem
Existing power amplifier circuits face inefficiencies and distortion issues due to their design, with class-A amplifiers being inefficient, class-B amplifiers having high distortion, class-G amplifiers experiencing glitches, and class-H amplifiers being complex and expensive.
Innovation Solution
A voltage supply circuit that uses two fixed voltage levels (Vlow and Vhigh) to set the amplifier supply voltage based on the output signal, switching between them smoothly to optimize power efficiency and linearity, with a control circuit managing the transition between Vlow and tracking the output voltage when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If class-G amplifier switches between two different supply voltage levels, then power efficiency is improved, but linearity is reduced and glitches occur in the output signal
Solution Approach 1:
The patent implements dynamic supply voltage switching between Vlow and Vhigh based on the instantaneous amplitude of the output signal. The control circuit monitors the output signal and dynamically selects the appropriate supply voltage level, allowing the amplifier to adapt its power consumption to the actual signal requirements while maintaining signal quality through smooth transitions.
Solution Approach 2:
The patent introduces a control circuit as an intermediary between the output signal and the supply voltage selection. This control circuit processes the output signal and generates appropriate control signals to switch between supply voltages, acting as a mediator that coordinates the switching action to minimize glitches and maintain linearity.
2Loss of energy
If class-H amplifier varies the supply voltage to track the output voltage level, then power efficiency and linearity are improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic supply voltage tracking where the supply voltage varies continuously to follow the output signal envelope. The control circuit generates a tracking voltage that dynamically adjusts the supply voltage level, enabling the amplifier to maintain optimal headroom across varying signal levels while improving efficiency.
Solution Approach 2:
The patent employs feedback mechanisms where the output signal is monitored and fed back to the control circuit, which then adjusts the supply voltage accordingly. This feedback loop ensures that the supply voltage tracks the output signal level, maintaining linearity and efficiency while managing complexity through systematic control.
3Reliability
If amplifier always operates at high power levels, then linearity is maintained, but power efficiency deteriorates
Solution Approach 1:
The patent dynamically adjusts the supply voltage based on the instantaneous signal level. During low-power periods, the amplifier operates at lower supply voltage (Vlow) to improve efficiency, while during high-power periods, it switches to higher supply voltage (Vhigh) to maintain linearity. This dynamic operation allows the amplifier to optimize both efficiency and linearity across different operating conditions.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on the signal characteristics. By adjusting the supply voltage level according to the output signal amplitude, the amplifier can operate efficiently at low power levels while maintaining linearity at high power levels, effectively resolving the contradiction between efficiency and linearity.
Data Source
AI summary
The present disclosure relates to a circuit for setting an amplifier supply voltage for an amplifier. The circuit comprises a switch circuit having a first transistor arranged to switchably couple a first supply voltage to a supply terminal of the amplifier and a second transistor arranged to switchably couple a second supply voltage to the supply terminal of the amplifier, wherein a magnitude of the first supply voltage is greater than a magnitude of the second supply voltage. The circuit further comprises a control circuit arranged to control the switch circuit to set an amplifier supply voltage at the supply terminal of the amplifier based on an output signal of the amplifier. The control circuit is configured to set the amplifier supply voltage to substantially equal the second supply voltage when a magnitude of a tracking voltage is less than the magnitude of the second supply voltage and set the amplifier supply voltage to track the amplifier output signal when the magnitude of the tracking voltage is greater than the magnitude of the second supply voltage.