Transceiver Self-Calibration via RSSI Feedback Loop

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Solution Overview

Problem

Existing transceiver designs face challenges in meeting design specifications due to RF analog block imperfections, leading to increased power consumption, design complexity, and manufacturing costs, particularly in requiring factory calibration for compensation.

Innovation Solution

A self-calibrating transceiver system that uses a calibration control state machine to set frequencies and gain for the transmitter and receiver chains, measuring RSSI and applying digital gain compensation values, allowing for on-device compensation of analog imperfections without factory calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If factory calibration is used to compensate for analog imperfections, then manufacturing precision is improved, but productivity deteriorates due to increased factory calibration time

Engineering Contradiction:

Improvecompensation accuracyVSAvoidfactory calibration time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs calibration actions preliminarily during device manufacturing by injecting test signals and measuring responses to determine offset values that are stored for later use. This preliminary calibration eliminates the need for time-consuming factory calibration procedures while maintaining compensation accuracy through pre-determined offset values.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The transceiver device performs self-calibration by automatically injecting test signals through its own transmitter chain and measuring the received signals using its receiver chain. The device determines its own offset values without requiring external calibration equipment or factory intervention, thereby eliminating factory calibration time while maintaining manufacturing precision.

Inventive Principle:

Principle #25Self-service

2Device complexity

If digital compensation circuits are added to support factory calibration, then device complexity is reduced compared to analog-only design, but productivity deteriorates due to increased factory calibration requirements

Engineering Contradiction:

Improvecircuit design complexityVSAvoidfactory calibration time

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The transceiver performs self-calibration using its own transmitter and receiver chains to automatically determine offset values for digital compensation circuits. This self-service approach eliminates the need for factory calibration procedures while maintaining the simplified digital compensation architecture, thereby resolving the contradiction between reduced device complexity and increased factory calibration time.

Inventive Principle:

Principle #25Self-service

3Productivity

If self calibration is implemented using existing transmitter and receiver chains, then productivity is improved by eliminating factory calibration, but measurement precision may deteriorate due to signal leakage paths

Engineering Contradiction:

Improvefactory calibration timeVSAvoidsignal measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent extracts and measures the signal leakage path characteristics by having the transmitter chain transmit test signals that leak through the duplexer or switch to the receiver chain. By separately measuring this leakage path and using it to determine offset values, the system compensates for the imperfections introduced by the leakage path, thereby maintaining measurement precision while achieving self-calibration.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful effect of signal leakage through the duplexer or switch into a beneficial measurement opportunity. By intentionally measuring the leaked test signals and using them to determine offset values for digital compensation, the system transforms the previously harmful leakage path into a useful calibration mechanism that maintains measurement precision while enabling factory calibration-free operation.

Inventive Principle:

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

Data Source

PatentUS10476612B2Transceiver system supporting receiver self calibration and methods of performing the same

Publication Date: 2019.11.12 SPREADTRUM COMMUNICATIONS USA INC

AI summary

A self-calibrating transceiver includes a baseband processor, a receiver chain comprising an amplifier and a digital front end (DFE), and a transmitter chain, and a calibration control state machine. The state machine stores amplifier gain steps and is in communication with the transmitter chain, the receiver chain, and the baseband processor. The state machine can set a receiver chain frequency at a predefined frequency and set a transmitter chain frequency to be offset relative to the receiver chain frequency. For each of the amplifier gain steps, the state machine can set a gain of the receiver chain and set a power of the transmitter chain. The baseband processor can measure an RSSI and transmit the measured RSSI to the state machine. The state machine can determine a digital gain compensation value based on the one or more measured RSSIs and apply the determined digital gain compensation value.