Cross-Coupled Differential Gain Circuit With Stable Frequency Response

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Solution Overview

Problem

Fully differential adjustable gain devices in wireless network receivers face challenges in maintaining consistent frequency response and input impedance when adjusting gain, as existing solutions require complex adjustments of multiple passive components.

Innovation Solution

A fully differential adjustable gain device with cross-coupled segments, where the gain is adjusted by modifying the component values of these segments while maintaining a specified relationship between them, allowing for consistent frequency response and input impedance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the gain of a fully differential device is adjusted by modifying passive components, then the gain is changed, but the frequency response and input impedance change undesirably

Engineering Contradiction:

Improvegain adjustmentVSAvoidfrequency response consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the configuration parameters of the cross-coupled segments (specifically the ratio relationship between components) to adjust gain while maintaining constant frequency response and input impedance characteristics. This is achieved by ensuring that when component values are adjusted for gain change, the ratio relationship remains constant, thereby preserving the frequency response.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces asymmetric cross-coupled segments with specific ratio relationships between components. The first cross-coupled segment has components with a first ratio relationship, while the second cross-coupled segment has components with a second ratio relationship. This asymmetric configuration enables independent control of gain and frequency response characteristics.

Inventive Principle:

Principle #4Asymmetry

2Reliability

If multiple passive components are adjusted to maintain frequency response while changing gain, then frequency response consistency is improved, but device complexity increases

Engineering Contradiction:

Improvefrequency response consistencyVSAvoidcomponent adjustment complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the feedback network into separate first and second cross-coupled segments. Each segment has its own ratio relationship that can be independently controlled. This segmentation allows gain adjustment through simple ratio modification without requiring complex coordinated adjustments of multiple passive components across the entire circuit.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cross-coupled segments serve multiple functions simultaneously: they provide gain control through ratio adjustment, maintain frequency response consistency through constant ratio relationships, and simplify the adjustment process. This multi-functionality reduces the overall complexity of the device while achieving the desired performance characteristics.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If complex component adjustments are made to maintain consistent input impedance, then input impedance consistency is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveinput impedance consistencyVSAvoidcomponent value precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent focuses on maintaining the ratio relationship between components in each cross-coupled segment rather than requiring precise absolute values. This approach to parameter control simplifies manufacturing requirements, as only the relative ratios need to be maintained with high precision, while absolute component values can vary within wider tolerances.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10587296B2Adjustable gain devices and methods for use therewith

Publication Date: 2020.03.10 FUTUREWEI TECHNOLOGIES INC

AI summary

The disclosure relates to technology for an adjustable gain device that includes differential input terminals, differential output terminals, signal processing circuitry, and first and second cross-coupled segments. The first cross-coupled segment is coupled between differential input terminals of the adjustable gain device and a negative input of the signal processing circuitry. The second cross-coupled segment is coupled between differential input terminals of the adjustable gain device and a positive input of the signal processing circuitry. The adjustable gain device has a gain that is adjustable by adjusting values of the first and second cross-coupled segments, while maintaining a substantially consistent frequency response and a substantially consistent input impedance of the adjustable gain device, so long as a specified relationship between values of the first and second cross-coupled segments is kept substantially constant.