Common-Gate Common-Source Amplifier With Difference Output for Low Noise

Solution Overview

Problem

Unified common-gate and common-source amplifiers in RFICs face a trade-off between noise performance and input matching range, with prior art techniques failing to significantly reduce the noise figure of such amplifiers.

Innovation Solution

A common-gate common-source amplifier design that incorporates a difference block with both NMOS and PMOS transistors to convert the voltage difference between common-gate and common-source outputs into a single-ended output, enhancing gain and noise performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a common-source amplifier is used, then noise performance is improved, but input matching range becomes narrow

Engineering Contradiction:

Improvenoise performanceVSAvoidinput matching range

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The amplifier is divided into two separate amplification paths: a common-source amplifier path and a common-gate amplifier path. Each path processes the input signal independently, allowing the noise advantages of common-source and the input matching advantages of common-gate to be utilized separately and then combined at the output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The outputs of the common-source amplifier and common-gate amplifier are merged through a difference block that combines the two output signals. This merging allows the beneficial characteristics of both amplifier topologies to be realized simultaneously in a single unified amplifier structure.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If a common-gate amplifier is used, then input matching range is improved, but noise figure increases

Engineering Contradiction:

Improveinput matching rangeVSAvoidnoise figure

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The amplifier is divided into two separate amplification paths: a common-source amplifier path and a common-gate amplifier path. Each path processes the input signal independently, allowing the noise advantages of common-source and the input matching advantages of common-gate to be utilized separately and then combined at the output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The outputs of the common-source amplifier and common-gate amplifier are merged through a difference block that combines the two output signals. This merging allows the beneficial characteristics of both amplifier topologies to be realized simultaneously in a single unified amplifier structure.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If prior art techniques for unifying common-gate and common-source topologies are used, then both topologies are combined in a single amplifier, but noise figure remains high

Engineering Contradiction:

Improveunified topologyVSAvoidnoise figure

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The amplifier is divided into two separate amplification paths: a common-source amplifier path and a common-gate amplifier path. Each path processes the input signal independently, allowing the noise advantages of common-source and the input matching advantages of common-gate to be utilized separately and then combined at the output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The outputs of the common-source amplifier and common-gate amplifier are merged through a difference block that combines the two output signals. This merging allows the beneficial characteristics of both amplifier topologies to be realized simultaneously in a single unified amplifier structure.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7902923B2Common-gate common-source amplifier

Publication Date: 2011.03.08 QUALCOMM INC

AI summary

Techniques for integrating a common-source and common-gate amplifier topology in a single amplifier design. In one aspect, an input voltage is provided to both a common-source amplifier and a common-gate amplifier. The output voltages of the common-source amplifier and the common-gate amplifier are provided to a difference block for generating a single-ended voltage proportional to the difference between the output voltages. When applied to the design of, e.g., low-noise amplifiers (LNA's), the disclosed techniques may offer improved noise performance over the prior art.