Gain Control Amplifier With Ladder Resistor Offset Compensation

Solution Overview

Problem

Conventional gain control amplifiers fail to completely remove DC offset components from output voltages, leading to increased chip area and power consumption, and require additional operational amplifiers and decoders for compensation.

Innovation Solution

A gain control amplifier design incorporating a non-inverting amplifier with a ladder-shaped resistor and offset compensator using multiple operational amplifiers to remove DC offset components without the need for a decoder, allowing variable voltage gain control via digital signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional gain control amplifier uses additional operational amplifiers and decoders for DC offset compensation, then DC offset removal is improved, but chip area and power consumption increase

Engineering Contradiction:

ImproveDC offset removalVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines the DC offset compensation function with the existing operational amplifiers in the gain control amplifier circuit. By merging the offset compensation function into the signal processing path and utilizing the existing amplifier stages, the design eliminates the need for separate compensation amplifiers and decoders, thereby reducing chip area while maintaining effective DC offset removal

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The existing operational amplifiers in the gain control amplifier are made multi-functional by enabling them to perform both signal amplification and DC offset compensation. The feedback network and resistor elements are configured to simultaneously achieve gain control and offset cancellation, making the circuit elements serve multiple purposes and eliminating dedicated compensation components

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conventional gain control amplifier uses additional operational amplifiers and decoders for DC offset compensation, then DC offset removal is improved, but power consumption increases

Engineering Contradiction:

ImproveDC offset removalVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent combines the DC offset compensation function with the existing operational amplifiers in the gain control amplifier circuit. By merging the offset compensation function into the signal processing path and utilizing the existing amplifier stages, the design eliminates the need for separate compensation amplifiers and decoders, thereby reducing chip area while maintaining effective DC offset removal

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The existing operational amplifiers in the gain control amplifier are made multi-functional by enabling them to perform both signal amplification and DC offset compensation. The feedback network and resistor elements are configured to simultaneously achieve gain control and offset cancellation, making the circuit elements serve multiple purposes and eliminating dedicated compensation components

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If conventional gain control amplifier uses decoder for gain control, then gain control precision is improved, but device complexity increases

Engineering Contradiction:

Improvegain control precisionVSAvoiddecoder complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the gain control function into discrete selectable gain stages achieved through the switching network configured with resistors. Instead of using a complex decoder to control multiple amplifiers, the design divides the gain control into segmented stages where each switch position selects a predetermined gain value, simplifying the control logic while maintaining precise gain selection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic gain control through a switching network that can rapidly reconfigure the feedback path based on control signals. The switches dynamically connect different resistor combinations to achieve gain switching, replacing the static and complex decoder architecture with a more flexible and simpler switching-based control mechanism

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7292094B2Gain control amplifier

Publication Date: 2007.11.06 SAMSUNG ELECTRONICS CO LTD

AI summary

A gain control amplifier is provided including: a non-inverting amplifier receiving an input voltage and a direct current reference voltage, and non-inverting amplifying and outputting an alternating component of the input voltage using a predetermined voltage gain based on the direct current reference voltage; and an offset compensator removing a direct current offset component from an output voltage of the non-inverting amplifier using at least two operational amplifiers. The non-inverting amplifier includes: a ladder-shaped resistor varying the voltage gain according to a digital control signal input from an external source.