Digital RSSI Circuit for Accurate Signal Detection

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Solution Overview

Problem

Conventional RSSI circuits in wireless communication devices suffer from high die area requirements, high power consumption, and imprecision due to analog summing amplifiers, process variations, and temperature variations, which affect the accuracy and speed of signal strength indication.

Innovation Solution

A digital RSSI circuit that converts analog input signals into progressively larger DC voltages, which are then compared to an internally generated reference voltage to produce digital values, eliminating the need for analog summing and reducing errors, with single-bit or multi-bit ADCs used to generate a digital RSSI value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an analog summing amplifier is used in the RSSI circuit, then the circuit can process multiple analog voltages, but the die area and power consumption increase

Engineering Contradiction:

Improvesignal processing capabilityVSAvoiddie area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent replaces the analog summing amplifier (mechanical/electrical system) with a digital processing system. Multiple analog voltages are converted to digital values by individual ADCs, then processed digitally to generate the RSSI value. This substitution eliminates the need for a large analog summing amplifier, reducing die area while maintaining the capability to process multiple signal inputs.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If an analog summing amplifier is used in the RSSI circuit, then the circuit can process multiple analog voltages, but power consumption increases

Engineering Contradiction:

Improvesignal processing capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent replaces the power-hungry analog summing amplifier with a digital processing architecture. Each input voltage is converted to digital by a dedicated ADC, then digital logic processes these values to compute the RSSI. Digital processing consumes significantly less power than high-precision analog summing, especially when using single-bit or low-resolution ADCs that can be implemented with minimal power.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the resolution parameter of the ADCs, using single-bit or low-bit ADCs instead of high-resolution analog-to-digital converters. This parameter change reduces the power consumption of the conversion process while still providing sufficient precision for RSSI measurement, thereby reducing overall power consumption of the circuit.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If conventional analog RSSI circuits are used, then the circuit can operate with existing receiver components, but measurement precision decreases due to process and temperature variations

Engineering Contradiction:

Improvecompatibility with receiver componentsVSAvoidsignal strength indication accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces the analog summing amplifier with individual ADCs for each input voltage. This substitution moves the conversion process to the digital domain, where precision is determined by the ADC reference voltage and digital logic rather than analog component matching. Digital processing is inherently more immune to process and temperature variations, improving measurement precision while maintaining compatibility with the existing receiver's analog output stages.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates separate ADC copies for each input voltage instead of using a single shared analog summing path. Each ADC independently converts its input voltage to digital, creating redundant conversion paths that eliminate the need for precise analog component matching. This copying approach ensures that each measurement path has its own precision reference, improving overall measurement accuracy.

Inventive Principle:

Principle #26Copying

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 digital RSSI circuit reduces die area and power consumption, enhances accuracy and speed, and eliminates errors associated with analog summing, enabling quicker AGC threshold detection and improved system throughput.

Implementation Method 1

converting the analog input signal into a plurality of DC voltages, where each successive DC voltage is progressively larger than a previous DC voltage, and converting the plurality of progressively larger DC voltages into a plurality of digital values

Methodology Applied

Scientific EffectAnalog to digital conversion:

Data Source

PatentUS7660567B1Digital received signal strength indicator (RSSI) circuit and method for detecting the strength of a received signal

Publication Date: 2010.02.09 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

An improved Received Signal Strength Indicator (RSSI) circuit and method is provided herein for quickly and accurately detecting the strength of a received signal. The circuit described herein provides a more accurate RSSI signal, while consuming less power and die area, by utilizing digital rather than analog summing.