RF Crest Factor Detection Using Shared RMS and Peak Sensing
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Solution Overview
Problem
Conventional RF detectors face challenges in accurately measuring peak and average power levels of modulated RF signals due to part-to-part, process, and temperature variations, requiring complex and costly matching circuitry and dividers, and suffer from reduced dynamic range and frequency dependence.
Innovation Solution
A wide-dynamic range RF detector that uses a single detector array for both average and instantaneous/peak power detection, employing a feedback control loop to normalize instantaneous power to average power, eliminating the need for an accurate divider and simplifying the system by using a variable gain detection subsystem with squaring detectors and interpolators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional parallel processing techniques are used to measure both average power and peak power, then both power levels can be obtained, but part-to-part, process, and temperature variations between different detectors degrade measurement accuracy and require complex matching circuitry
Solution Approach 1:
The patent combines both average power detection and peak power detection functions into a single detector by integrating an envelope detector and an average power detector. This unified detector processes the input signal through shared circuitry including a squarer, integrator, and feedback control loop, eliminating the need for separate detectors and their associated matching circuitry. The single detector architecture ensures that both power measurements are subject to the same environmental variations, thereby improving measurement accuracy without requiring complex matching.
Solution Approach 2:
The detector is designed to perform multiple functions simultaneously: it detects both the envelope (peak power) and the average power of the input signal using a single integrated circuit. The detector includes circuitry that can operate in different modes to provide both peak power detection and average power detection, making it a universal power measurement device that eliminates the need for multiple specialized detectors and their matching network.
2Adaptability or versatility
If separate detectors are used for average power and peak power detection, then both measurements can be obtained, but the system requires an RF coupler to drive both channels and increases overall system complexity
Solution Approach 1:
The patent merges the average power detection channel and the envelope detection channel into a single integrated detector. The input signal is processed through shared components including a squarer, integrator, and feedback control loop that serve both detection functions. This eliminates the need for an RF coupler to split the signal to multiple detectors and removes the complexity of driving separate detection channels.
3Measurement precision
If an accurate divider is used to calculate crest factor from peak and average power measurements, then measurement accuracy is improved, but the divider must handle nonlinear calculations and may require complex and expensive circuitry
Solution Approach 1:
The patent employs a feedback control loop that uses the average power detection output to control a variable gain amplifier in the envelope detection path. This feedback mechanism automatically adjusts the gain to compensate for variations in the input signal level, ensuring that the crest factor calculation remains accurate without requiring a complex divider circuit. The feedback loop linearizes the overall response and eliminates the need for nonlinear division operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides accurate indications of average power, instantaneous power, and peak-to-average power ratio over a wide range of input power levels and modulation complexities, improving accuracy and reducing system complexity and cost.
Implementation Method 1
detecting the plurality of representations of the input signal at the plurality of gain levels includes squaring the plurality of representations of the input signal
Implementation Method 2
an integrator coupled to the variable gain detection subsystem and configured to receive the detector output signal and a reference signal and to provide an integrator output signal which is representative of an average power level of the input signal
Data Source
AI summary
An RF detector configured to provide two outputs, one being a function of the true RMS power level of an RF input signal, and the other being a function of the instantaneous/peak power of the RF input signal, normalized to the average power level. The RF detector includes a variable gain detection subsystem including a single detector or detector array that provides a representation of the power level of the RF input signal. The detector or detector array is common to both the RMS power detection channel and the instantaneous/peak power detection channel of the RF detector. A method of RF detection includes providing representations of the RF input signal at different gain levels, selecting one or more of the representations, and averaging the selected signals. The gain levels of the selected representations is adjusted to provide information about the average power level of the RF input signal.