Single-Ended Receiver Amplifier With Differential Output Noise Reduction

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Solution Overview

Problem

Prior art receivers with amplifiers suffer from high noise figures due to the need for baluns to couple single-ended antennas to differential inputs, resulting in signal losses and increased noise, which is exacerbated by impedance mismatching and the introduction of noise-generating resistors.

Innovation Solution

A receiver amplifier design with a single-ended input and differential output that reduces common mode input impedance using a differential inductor with a center tap and a coupling factor of 0.5 to 1.0, eliminating the need for noise-generating resistors and allowing for on-chip realization, while maintaining input power match.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a balun is used to couple a single-ended antenna to a differential input, then the amplifier can receive the antenna signal, but the chip area increases and signal losses increase

Engineering Contradiction:

Improveability to receive antenna signalVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent extracts and eliminates the balun component from the system by redesigning the amplifier input stage. Instead of using a separate balun to convert single-ended to differential signals, the amplifier directly accepts single-ended input through a simplified input stage with a first transistor and associated impedance matching network, thereby removing the source of signal losses and chip area consumption.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the functions of the balun and the amplifier input stage into a single integrated structure. The single-ended input stage combines impedance matching, signal reception, and amplification functions that were previously separated into distinct components (balun + differential amplifier input), reducing overall chip area while maintaining signal integrity.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If a balun is used to couple a single-ended antenna to a differential input, then the amplifier can receive the antenna signal, but signal losses increase and noise figures increase

Engineering Contradiction:

Improveability to receive antenna signalVSAvoidsignal losses and noise

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the balun component that causes signal losses and noise figure degradation. By directly coupling the single-ended antenna to a purpose-designed single-ended input stage, the system eliminates the conversion losses and noise addition that occur in differential-to-single-ended conversion paths.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the input configuration parameters from differential to single-ended, and adjusts the impedance matching network parameters (inductors and capacitors) to optimize signal transfer. This parameter change eliminates the need for balun conversion and reduces signal losses while improving noise figure.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If only one first main electrode is used as amplifier input to avoid balun, then chip area is reduced, but impedance mismatching occurs resulting in signal losses

Engineering Contradiction:

Improvechip areaVSAvoidsignal losses from impedance mismatching

Core Design Contradiction:

Area of stationary objectVSLoss of energy

Solution Approach 1:

The patent applies local quality optimization by designing a dedicated single-ended input stage with specifically tailored impedance matching components (first inductor, second inductor, third capacitor, fourth capacitor) that are optimized for single-ended signal reception. This localized optimization ensures proper impedance matching at the input stage without requiring a balun, eliminating signal losses while maintaining compact chip area.

Inventive Principle:

Principle #3Local quality

4Loss of energy

If an impedance matching resistor is introduced to reduce impedance mismatching, then signal losses are reduced, but noise figure increases

Engineering Contradiction:

Improvesignal losses from impedance mismatchingVSAvoidnoise figure

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the noise-generating impedance matching resistor with a reactive impedance matching network consisting of inductors and capacitors. These reactive components provide impedance matching without dissipating signal power as heat or adding thermal noise, effectively substituting a noisy component with quieter alternatives that achieve the same impedance transformation function.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS7812675B2Receiver comprising an amplifier

Publication Date: 2010.10.12 STMICROELECTRONICS INT NV

AI summary

The invention relates to a receiver (1) comprising an amplifier (31-34) for amplifying an antenna signal, which amplifier (31-34) comprises an amplifier input (11a) and an amplifier output (12a,12b), the amplifier input (11a) being a single ended input for receiving the antenna signal, the amplifier output (12a, 12b) being a differential output, and the amplifier (31-34) comprising circuit (41,42) for reducing a common mode input impedance of the amplifier (31-34).