VRF Equalizer Circuit for Doherty ET Ripple Cancellation
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Solution Overview
Problem
Envelope tracking for Doherty power amplifiers results in non-linear currents and undesirable ripples due to load modulation, which affects the efficiency and performance of power amplifiers in wireless communication devices.
Innovation Solution
A virtual radio frequency (VRF) equalizer is integrated into the envelope tracking integrated circuit (ETIC) to cancel ripple caused by load modulation, using circuitry that includes a first transform function and additional components to compensate for the amplifier, improving overall performance and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If load modulation is used for envelope tracking in Doherty power amplifiers, then efficiency requirements are met, but non-linear currents and undesirable ripples are generated
Solution Approach 1:
The patent applies ripple cancellation circuitry that converts the harmful ripple effect into a beneficial outcome by generating an equal and opposite ripple signal to cancel the original ripple. The cancellation circuitry processes the envelope signal to extract ripple components and generates compensating signals that when combined with the original signal, eliminate the harmful ripple while preserving the load modulation benefits for efficiency.
Solution Approach 2:
The patent introduces ripple cancellation circuitry as an intermediary component between the envelope tracking signal source and the power amplifier load. This intermediary circuit processes the envelope signal, extracts ripple components, and generates compensating signals that mediate the interaction between the amplifier and load, thereby eliminating ripple without removing the efficiency-providing load modulation.
2Use of energy by moving object
If load modulation is used for envelope tracking in Doherty power amplifiers, then efficiency requirements are met, but non-linear currents are generated
Solution Approach 1:
The patent applies ripple cancellation circuitry that converts the harmful non-linear current effect into a beneficial outcome by generating equal and opposite current components to cancel the non-linearity. The cancellation circuitry processes the envelope signal to extract non-linear current components and generates compensating signals that when combined with the original signal, linearize the current while preserving the load modulation benefits for efficiency.
Solution Approach 2:
The patent introduces ripple cancellation circuitry as an intermediary component that processes the envelope signal and generates compensating signals. This intermediary linearizes the non-linear current by adding corrective current components, thereby mediating between the non-linear load modulation and the requirement for linear current, allowing both efficiency and current linearity to be achieved.
3Object-generated harmful factors
If ripple cancellation circuitry is added to the ETIC, then ripple is reduced, but device complexity increases
Solution Approach 1:
The patent merges the ripple cancellation functionality with the existing envelope tracking integrated circuit (ETIC) by integrating ripple cancellation circuitry within the same device. The cancellation circuitry shares common components and signal paths with the envelope tracking functionality, combining multiple functions into a single integrated circuit rather than adding separate external components, thereby reducing overall system complexity.
Solution Approach 2:
The patent implements multi-functional circuitry within the ETIC that simultaneously performs envelope tracking and ripple cancellation. The same integrated circuit processes the envelope signal for both tracking purposes and ripple extraction/cancellation purposes, making the device universal in its functionality and avoiding the need for separate dedicated ripple cancellation hardware, thus minimizing complexity increase.
Data Source
AI summary
A virtual radio frequency (VRF) equalizer for an envelope tracking integrated circuit (ETIC) is disclosed. In one aspect, an ETIC provides envelope tracking (ET) for a barely Doherty (BD) power amplifier stage. The VRF equalizer includes circuitry that provides ripple cancellation that is caused by load modulation of the BD power amplifier stage. Additional circuitry is included to compensate for an amplifier within the ETIC. By canceling the ripple within the ETIC, the overall performance and efficiency of the BD power amplifier stage is improved, resulting in better performance of a transmitter in a wireless communication device.