Diode Linearizer Circuit for Intermodulation Distortion Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic circuits, particularly radar receivers, face significant challenges in reducing intermodulation distortion due to non-linear components, which current solutions like high power amplifiers or complex distortion cancellation techniques fail to address effectively, often increasing noise and complexity.
Innovation Solution
A novel linearizer circuit using a starved limiter configuration with biased diodes and reactive elements is introduced to provide gain expansion that counteracts gain compression in non-linear devices, improving linearity and reducing third-order intermodulation distortion by creating a level-dependent load that decreases loss as signal levels increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If higher linearity components such as high power amplifiers are used, then intermodulation distortion is reduced, but device size, power consumption, and cost increase
Solution Approach 1:
The system separates the distortion generation and cancellation functions into distinct components: the non-linear device generates the signal and distortion, while the linearizer circuit separately generates and subtracts the distortion components. This segmentation allows using a simple non-linear device without requiring the entire system to be high-linearity.
Solution Approach 2:
The linearizer circuit acts as an intermediary that processes the output signal, extracts distortion components, and subtracts them from the original signal. This intermediary approach enables distortion reduction without modifying the original non-linear device or requiring high-power amplifiers.
2Object-generated harmful factors
If distortion cancellation techniques such as feedforward cancellation or predistortion modulation are employed, then intermodulation distortion is reduced, but circuit complexity increases and noise figure deteriorates
Solution Approach 1:
The linearizer circuit focuses its action locally on the distortion frequency components rather than processing the entire signal spectrum. By targeting only the intermodulation products for cancellation, the circuit achieves effective distortion reduction with simpler architecture and lower noise impact.
3Object-generated harmful factors
If distortion cancellation techniques are used, then intermodulation distortion is reduced, but noise figure increases
Solution Approach 1:
The linearizer creates a copy of the distortion components present in the original signal and subtracts this copy from the main signal path. This copying approach allows precise distortion cancellation while maintaining a separate, low-noise processing path that does not directly impact the main signal's noise figure.
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 linearizer effectively increases the third-order intercept point (IP3) by up to 7 dBm, enhancing linearity and reducing distortion with minimal added complexity and noise, suitable for various frequency ranges and signal levels.
Implementation Method 1
The circuit includes a starved limiter in shunt with the device, implemented using a pair of biased diodes D1 and D2
Implementation Method 2
a plurality of reactive elements for increasing the operational bandwidth of the linearizer
Data Source
AI summary
A linearizer for reducing intermodulation distortion in a non-linear device. The novel linearizer includes an input port for receiving a signal from the device and a circuit for effecting gain expansion on the signal that counteracts a gain compression of the device. In an illustrative embodiment, the circuit includes a starved limiter in shunt with the device, implemented using a pair of biased diodes D1 and D2. The first diode D1 is connected to ground and the second diode D2 is coupled to the signal. In an alternate embodiment, the linearizer also includes a second pair of biased diodes D3 and D4, D3 connected to ground and D4 coupled to the signal, and a plurality of reactive elements for increasing the operational bandwidth of the linearizer.