APC Loop Filtering for Multi-Transmitter RF Interference

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Solution Overview

Problem

Unwanted interference from signals associated with different radio access technologies can disrupt the power control loop in wireless communications circuitry, leading to incorrect power levels for transmitted radio-frequency signals.

Innovation Solution

Incorporating a filter circuit within the control loop to reject interfering signals from secondary transceivers, using a radio-frequency coupler to couple feedback signals from both primary and secondary transceivers, and employing digital filters to ensure accurate power control adjustments based on filtered feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a radio-frequency coupler is used to couple feedback signals from both primary and secondary transceivers, then the power control loop can receive comprehensive feedback, but interfering signals from secondary transceivers disrupt the power control loop causing incorrect power levels

Engineering Contradiction:

Improvepower control accuracyVSAvoidinterference from secondary transceivers

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The feedback signal is segmented into separate frequency components corresponding to different transceivers. The filter circuit separates the primary transceiver feedback from secondary transceiver interference, allowing independent processing of each signal component to eliminate interference while maintaining comprehensive feedback.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A filter circuit is introduced as an intermediary component between the radio-frequency coupler and the power control loop. This filter acts as a mediator that selectively passes desired feedback signals while blocking interfering signals from secondary transceivers, enabling accurate power control without interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If multiple transceivers share a common antenna, then device complexity is reduced, but signals from different radio access technologies interfere with each other

Engineering Contradiction:

Improveantenna configurationVSAvoidinterference between transceivers

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The harmful interference components are extracted and removed from the combined feedback signal using frequency-selective filtering. The filter circuit identifies and extracts only the relevant feedback signals for the primary transceiver while taking out (removing) interfering signals from secondary transceivers, enabling clean power control.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The presence of multiple transceiver signals in the feedback path, which initially appears harmful, is converted into a benefit by using frequency-selective filtering to recover useful information. The interference signals provide frequency discrimination opportunities that enable precise separation and selection of desired feedback components for accurate power control.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If digital filtering is applied to the feedback signal, then interference suppression is improved, but additional circuitry increases device complexity

Engineering Contradiction:

Improveinterference suppressionVSAvoidfilter circuit implementation

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Analog or RF filtering approaches are replaced with digital filtering implementation. The filter circuit operates in the digital domain after analog-to-digital conversion, using software-based or programmable digital signal processing to achieve interference suppression. This substitution provides flexible, reconfigurable filtering with precise frequency selectivity while reducing hardware complexity compared to high-performance analog filters.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20240364366A1Wireless Circuitry having Power Control Loop with Interference Suppression Filter

Publication Date: 2024.10.31 APPLE INC

AI summary

Wireless circuitry may include at least first and second transmit paths coupled to one or more antennas via a radio-frequency coupler. The radio-frequency coupler can receive via switching and filter circuitry a first radio-frequency signal from the first transmit path and a second radio-frequency signal from the second transmit path. The radio-frequency coupler can be coupled to an automatic power control (APC) loop for dynamically adjusting a signal power level of the first radio-frequency signal. The APC loop can include a feedback receiver and a power control circuit having first and second inputs. A first digital filter can be coupled at the first input of the power control circuit and can be configured to reject the second radio-frequency signal. A second digital filter matching the first digital filter can be coupled at the second input of the power control circuit and can be configured to filter a reference baseband signal.