Log-Linear RF Power Detector for Wide Dynamic Range Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF power detectors exhibit low sensitivity at low power levels and high sensitivity at high power levels, leading to an exponential response that is difficult to accurately read, necessitating a power detector with increased dynamic range and consistent sensitivity across the entire power range.
Innovation Solution
A log-linear power detector comprising a transconductance element that outputs a rectified detection current increasing exponentially with RF signal power, and at least one p-n junction based device, where the output voltage is a function of the voltage across the p-n junction, providing a linear relationship between detector output voltage and logarithmic input power, along with comparing circuitry to compensate for temperature non-linearity and adjust current paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional power detector is used, then the detector can measure RF signal power, but the sensitivity varies exponentially with power level, providing low sensitivity at low power levels and high sensitivity at high power levels
Solution Approach 1:
The patent transforms the exponential parameter relationship into a linear one by using a logarithmic function. The output voltage is made proportional to the logarithm of the input power level, which converts the exponential sensitivity variation into a linear response across the entire dynamic range, providing consistent sensitivity from low to high power levels
Solution Approach 2:
The patent introduces an intermediate logarithmic processing stage between the RF input and the voltage output. This intermediary transformation layer converts the exponential power-voltage relationship into a linear logarithmic relationship, enabling consistent measurement sensitivity across different power levels
2Speed
If the detector output voltage changes rapidly at higher power outputs, then the detector responds to power changes, but the rapid change exceeds the ability to properly read the signal
Solution Approach 1:
The patent changes the functional relationship from exponential to linear by applying a logarithmic transformation. This parameter change slows down the rate of voltage change at high power levels while maintaining proportional response, making the output readable across the entire power range without exceeding measurement capabilities
3Measurement precision
If a linear power detector response is desired, then consistent sensitivity across power levels is achieved, but conventional detectors provide exponential response instead
Solution Approach 1:
The patent achieves linear response by changing the mathematical parameter relationship from exponential to logarithmic. This is accomplished through circuit design that implements the logarithmic function, providing consistent sensitivity across power levels while maintaining a practical detector structure suitable for integrated circuit implementation
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 achieves a linear relationship between detector output voltage and input power, enhancing sensitivity and dynamic range, allowing for accurate monitoring of RF signal power across the entire range, from low to high intensities.
Implementation Method 1
at least one p-n junction based device, a function of the rectified detection current arranged to flow there through. The output of the power detector is a function of the voltage across the at least one p-n junction based device
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A power detector constituted of: a transconductance element arranged to output a rectified detection current, the magnitude thereof arranged to increase exponentially responsive to a linear increase in the amplitude of an input signal; and at least one p-n junction based device, a function of the rectified 5 detection current arranged to flow there through. The output of the power detector is a function of the voltage across the at least one p-n junction based device.