RF Power Amplifier Turn-On Gain Compensation for WiFi Bursts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
RF power amplifiers in WiFi transmitters face linearity degradation due to power amplifier non-linearity, noise, bandwidth limitations, and transient turn-on gain variations, which affect error vector magnitude (EVM), especially during bursted signal excitation.
Innovation Solution
A power amplification apparatus with an open loop transient gain compensation circuit that generates a transient compensation current to be added to the bias current, using a memory circuit with registers and capacitors to control the compensation current's amplitude and time constant, specifically addressing transient turn-on gain variations during transmission bursts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power amplifier is used to amplify RF signals in WiFi transmitters, then signal transmission capability is improved, but transient turn-on gain variations occur during bursted signal excitation
Solution Approach 1:
The patent applies preliminary action by generating a transient compensation current before the power amplifier's gain transient settles. The compensation current is generated in response to a transient compensation signal that is applied to a current input of the power amplifier prior to the signal being amplified, allowing the amplifier to maintain stable gain during bursted signal excitation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a transient compensation signal and transient compensation current as intermediate elements. These compensation signals are generated by circuitry within the power amplifier and used to counteract the gain variations, serving as a mediator between the input signal and the amplified output.
2Productivity
If the power amplifier operates during bursted signal excitation, then data transmission is enabled, but transient turn-on gain variation degrades error vector magnitude
Solution Approach 1:
The compensation mechanism is activated in advance during the transient turn-on period of the power amplifier. The transient compensation signal is generated and applied to the current input before the amplified signal output occurs, allowing the system to maintain precision during high-speed data transmission bursts.
Solution Approach 2:
The patent implements a feedback mechanism where the transient compensation signal is generated based on the detection of gain transients in the power amplifier. The compensation current is continuously adjusted in response to the transient conditions, improving error vector magnitude through dynamic feedback control during bursted transmission.
3Stability of the object's composition
If transient compensation current is added to bias current, then transient turn-on gain variation is compensated, but circuit complexity increases
Solution Approach 1:
The patent merges the transient compensation function with the existing power amplifier circuitry. The transient compensation signal is generated within the power amplifier itself, and the compensation current is combined with the bias current through shared circuit elements, reducing overall system complexity while maintaining gain stability.
Solution Approach 2:
The power amplifier circuitry is designed to perform multiple functions: amplifying the RF signal, generating the transient compensation signal, and providing the compensation current. This multi-functionality reduces the need for separate dedicated compensation circuits, thereby limiting the increase in device complexity.
Data Source
AI summary
A power amplifier includes a power amplifier stage configured to amplify a signal received from an attenuator or from a variable gain amplifier. An open loop transient gain compensation circuit compensates a transient turn-on gain variation of the power amplifier stage with a transient compensation current added to a bias current supplied to the attenuator or supplied to the variable gain amplifier.