RSSI Generation Using AGC and ADC Codes for Wide RF Dynamic Range

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Solution Overview

Problem

RF communications devices face challenges in supporting a wide dynamic range of signal strengths due to varying coupling conditions, requiring efficient methods to adjust signal amplification without separate RSSI measurement devices.

Innovation Solution

A method and system that generate an RSSI value by combining attenuation factor codes and ADC codes through bit shift operations, using AGC devices with programmable resistive or capacitive voltage dividers, and signal envelope detection, to produce a combined RSSI value that adjusts amplifier gains effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a separate RSSI measurement device is used to measure signal strength, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvesignal strength measurementVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the RSSI measurement function with the existing AGC and ADC circuits. The AGC circuit generates an attenuation factor code that reflects signal strength, and the ADC converts the attenuated signal to a digital code. These two codes are combined through bit shift operations to produce the RSSI value, eliminating the need for a separate RSSI measurement device while maintaining measurement accuracy.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The AGC circuit is given a dual function: it not only controls gain to maintain signal levels but also provides attenuation information for RSSI measurement. The ADC similarly serves both to convert the signal for processing and to provide digital code data for RSSI calculation. This multi-functionality reduces overall device complexity while preserving measurement capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If traditional separate RSSI measurement and AGC circuits are used, then measurement accuracy is maintained, but power consumption increases

Engineering Contradiction:

ImproveRSSI measurement accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent combines the RSSI measurement path with the existing signal processing path (AGC and ADC). Instead of having separate circuits for RSSI measurement and signal processing, the system reuses the attenuation factor code from AGC and the digital code from ADC, combining them through efficient bit shift operations. This sharing of circuit resources significantly reduces power consumption while maintaining measurement accuracy.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If attenuation factor code and ADC code are combined through bit shift operation, then device complexity is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecircuit complexityVSAvoidbit alignment precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent replaces complex analog signal combining circuits with digital bit shift operations. Instead of using precision analog components to combine attenuation and signal level information, the system uses digital logic to shift and combine binary codes. This substitution reduces device complexity and improves manufacturability, as digital logic is more tolerant of manufacturing variations than precision analog circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach allows RF communications devices to seamlessly handle both long and short distance communications with reduced power consumption and circuit complexity, supporting a wide dynamic range while minimizing energy costs and thermal emissions.

Implementation Method 1

obtaining the attenuation factor code involves obtaining the attenuation factor code using a programmable resistive voltage divider

Methodology Applied

Scientific EffectVoltage division: Ohm's Law

Implementation Method 2

obtaining the attenuation factor code involves obtaining the attenuation factor code using a programmable capacitive voltage divider

Methodology Applied

Scientific EffectVoltage division: Capacitance

Implementation Method 3

obtaining the ADC code involves converting the buffered signal envelope into the ADC code

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Implementation Method 4

the method for generating the RSSI value that corresponds to the RF signal further involves detecting a signal envelope of the signal that results from the AGC operation

Methodology Applied

Scientific EffectSignal envelope detection:

Data Source

PatentUS9853752B2Method and system for generating a received signal strength indicator (RSSI) value that corresponds to a radio frequency (RF) signal

Publication Date: 2017.12.26 NXP BV

AI summary

Embodiments of a method and a system for generating a received signal strength indicator (RSSI) value that corresponds to a radio frequency (RF) signal are disclosed. In an embodiment, a method for generating an RSSI value that corresponds to an RF signal involves obtaining an attenuation factor code in response to applying an automatic gain control (AGC) operation to the RF signal, obtaining an analog-to-digital converter (ADC) code in response to applying an ADC operation to a signal that results from the AGC operation, and combining the attenuation factor code and the ADC code to generate an RSSI value. Other embodiments are also described.