WLAN Receiver AGC with Single-Rail Power Estimation
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Solution Overview
Problem
WLAN devices spend significant power due to continuous operation of both in-phase and quadrature power estimators during listen mode, which is necessary for automatic gain control, leading to high power consumption.
Innovation Solution
Implement a receiver with a power estimator that selectively activates either the in-phase or quadrature power estimator, using single-rail power estimation during listen mode and switching to IQ power estimation upon detecting a WLAN frame, thereby conserving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both in-phase and quadrature power estimators are operated continuously during listen mode, then automatic gain control accuracy is maintained, but power consumption increases significantly
Solution Approach 1:
The power estimation function is segmented into two separate estimators (in-phase and quadrature), allowing selective activation. During listen mode, only one estimator is activated while the other remains inactive, reducing power consumption. When a frame is detected, both estimators are activated to maintain AGC accuracy during data reception.
Solution Approach 2:
The system dynamically switches between different operational states: during listen mode, only one power estimator is active; upon frame detection, the system transitions to activating both estimators. This dynamic adaptation allows the system to optimize power consumption based on operational requirements while maintaining measurement precision when needed.
2Use of energy by moving object
If single-rail power estimation is used during listen mode, then power consumption is reduced, but measurement capability is limited compared to IQ power estimation
Solution Approach 1:
During listen mode, the system employs partial action by activating only one power estimator instead of both, accepting reduced measurement capability in exchange for significant power savings. When a frame is detected, the system transitions to full action by activating both estimators, ensuring complete measurement capability is available when needed for accurate AGC operation during data reception.
Data Source
Figure 1A~1B
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AI summary
An example receiver includes: a first power estimator operable to receive an in-phase signal; a second power estimator operable to receive a quadrature signal; a combiner coupled to outputs of the first and second power estimators, the combiner having an output that supplies estimated signal power; and an automatic gain controller coupled to the output of the combiner, the automatic gain controller operable to, in a first mode, turn off one of the first or second power estimators such that the one of the first or second power estimators is an inactive power estimator and the other is an active power estimator, and control the combiner to generate the estimated signal power using a function of an output of active power estimator.