ADC Gain Control Using Peak-to-Average Ratio Under RF Interference
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Solution Overview
Problem
Existing receivers, such as GPS receivers, face inefficiencies in dynamic range utilization due to radio frequency interference, as RMS-based automatic gain control circuits fail to maintain optimal operation when interference is present, leading to suboptimal performance.
Innovation Solution
A method and system that estimate the peak-to-average ratio of an analog signal from digital samples to determine a peak value, allowing the automatic gain control circuit to adjust the gain and maintain the signal magnitude at the ADC input, effectively controlling the receiver's operating range and detecting narrow band interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RMS based automatic gain control circuit is used, then the dynamic range of ADC is efficiently utilized when only desired signal is present, but the dynamic range utilization deteriorates when RF interference is present
Solution Approach 1:
The patent changes the control parameter from RMS (root-mean-square) to peak-to-average ratio (PAR). The PAR metric better characterizes signals with interference by comparing peak amplitude to average power, allowing the AGC to maintain optimal ADC utilization even when RF interference is present. This parameter change enables the system to distinguish between desired signal characteristics and interference characteristics.
Solution Approach 2:
The patent replaces the traditional RMS-based AGC mechanism with a PAR-based AGC mechanism. By substituting the mathematical foundation from second-order statistics (RMS) to a combination of peak detection and average power calculation, the system achieves better performance in interference environments while maintaining efficiency in clean environments.
2Stability of the object's composition
If gain is reduced to maintain constant RMS amplitude in presence of interference, then combined RMS amplitude is kept constant, but signal quality deteriorates
Solution Approach 1:
The patent changes the control parameter from RMS to peak-to-average ratio (PAR). Instead of controlling gain based on RMS amplitude which conflates signal and interference, the PAR-based control separates peak signal characteristics from average power, allowing the system to maintain signal quality while accounting for interference presence. The PAR metric remains stable for the desired signal even when interference varies the RMS amplitude.
3Reliability
If high SQNR is required to handle high magnitude RF interference, then interference management is improved, but system feasibility deteriorates
Solution Approach 1:
The patent introduces PAR as an intermediary metric between the raw signal and the AGC control decision. Rather than directly responding to high-magnitude interference that would require high SQNR, the PAR metric serves as a mediator that characterizes the desired signal's peak-to-average relationship, allowing the AGC to adjust gain based on signal characteristics rather than absolute magnitude, thus avoiding the need for high SQNR in interference environments.
Data Source
AI summary
Automatic gain control in a receiver. A method for controlling operating range of an analog-to-digital converter (ADC) by an automatic gain control circuit includes estimating a peak-to-average ratio corresponding to an analog signal from digital samples of the analog signal. The method includes determining a peak value corresponding to the analog signal based on the peak-to-average ratio. Further, the method includes maintaining magnitude of the analog signal at an input of the ADC and gain of the receiver based on the peak value.