Receiver PIM Compensation Using Auxiliary IMP Estimation
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Solution Overview
Problem
Existing methods for compensating for Passive Intermodulation (PIM) distortion in wireless communication devices require excessive digital resources or make restrictive assumptions about non-linear behavior, making them inefficient and inaccurate, especially for multi-carrier or multi-band systems.
Innovation Solution
A system that includes a tunable non-linear circuit and an adaptive filter to generate and estimate PIM distortion, using a low-power auxiliary transmitter and digital filter to model the difference between the main and auxiliary transmit paths, thereby reducing PIM distortion in the receiver output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a polynomial model is used to estimate PIM distortion in the digital domain, then PIM distortion can be modeled, but a very large number of polynomial orders are required which prohibitively increases digital resources
Solution Approach 1:
The patent replaces the digital domain polynomial modeling approach with an analog domain circuit-based approach. A tunable non-linear circuit generates IMP signals that replicate the PIM distortion characteristics, eliminating the need for high-order polynomial calculations in the digital domain while maintaining estimation accuracy.
Solution Approach 2:
The patent creates a copy of the PIM distortion characteristics using the tunable non-linear circuit. This circuit generates IMP signals that are copies of the actual PIM distortion produced by the passive device, allowing the distortion to be estimated and compensated without requiring complex digital polynomial models.
2Adaptability or versatility
If the non-linear behavior of the PIM source is assumed to be similar to the power amplifier's non-linearity, then compensation can be applied, but this assumption is very restrictive and inaccurate for different PIM sources
Solution Approach 1:
The patent makes the non-linear circuit tunable to dynamically adjust its characteristics. The circuit can be tuned to match the specific non-linear behavior of different PIM sources by adjusting component values or operating conditions, allowing accurate modeling of various PIM sources without restrictive assumptions.
Solution Approach 2:
The patent customizes the non-linear circuit to match the specific local characteristics of each PIM source. By tuning the circuit parameters to match the particular IMP ratios and distortion characteristics of a specific passive device, the system achieves accurate modeling for that local condition rather than using a generic model.
Data Source
AI summary
The present disclosure relates to compensation for Passive Intermodulation (PIM) distortion in a receiver. In one embodiment, a main receiver receives a radio frequency receive signal and outputs a main receiver output signal. In order to compensate for PIM distortion, a tunable non-linear circuit generates an Intermodulation Products (IMP) signal that includes a number of IMPs as a function of a signal that is indicative of the radio frequency transmit signal. An auxiliary receiver receives the IMP signal and outputs an auxiliary receiver output signal that includes only a subset of the IMPs that fall within a passband of the main receiver. The auxiliary receiver output signal is adaptively filtered to provide a PIM estimate signal, which is then subtracted from the main receiver output signal to provide a compensated output signal.