CMOS Variable Gain Amplifier Using Region Merging
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Solution Overview
Problem
Conventional CMOS variable gain amplifiers have a limited variable gain range, high current consumption, and large design area due to complex circuits and high noise factors, which hinder their performance in RF communication transceivers.
Innovation Solution
A CMOS variable gain amplifier design that combines operation regions between saturation and triode regions within a feedback loop, using a combination circuit with bias input, operation region, and feedback circuits to achieve a wider gain range, reduce current consumption, and improve noise factors, while maintaining a simple design area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional CMOS variable gain amplifier uses multiple transistors to achieve variable gain, then the gain control function is provided, but the circuit becomes complicated, current consumption increases, noise factor increases, and design area increases
Solution Approach 1:
The patent combines the functions of multiple transistors into a single transistor by utilizing both saturation and triode regions. The transistor operates in saturation region for high gain and triode region for low gain, merging what would traditionally require separate transistor circuits into one unified device, thereby reducing circuit complexity while maintaining variable gain functionality
Solution Approach 2:
The single transistor is designed to perform multiple functions by operating in different regions. The same transistor provides both high-gain amplification (saturation region) and low-gain amplification (triode region), making it a multi-functional component that replaces what would traditionally require multiple specialized transistors
2Adaptability or versatility
If a conventional CMOS variable gain amplifier uses multiple transistors, then gain control is achieved, but current consumption increases
Solution Approach 1:
The patent merges multiple transistor functions into a single transistor, reducing the total number of active devices from multiple to one. This consolidation directly reduces current consumption since fewer transistors are drawing current, while the single transistor maintains variable gain capability through regional operation switching
3Adaptability or versatility
If a conventional CMOS variable gain amplifier uses multiple transistors, then gain control is achieved, but design area increases
Solution Approach 1:
The patent consolidates what would be multiple transistor layouts into a single transistor structure. By merging the functions of multiple devices into one, the physical design area is reduced while the variable gain functionality is preserved through the transistor's ability to operate in different regions
4Adaptability or versatility
If a conventional CMOS variable gain amplifier uses multiple transistors, then gain control is achieved, but noise factor increases
Solution Approach 1:
The patent reduces noise by merging multiple transistor sources of noise into a single transistor. With fewer active devices, there are fewer noise generation points, and the single transistor's noise can be better controlled through region-specific operation, thereby improving the overall noise factor while maintaining variable gain
Data Source
AI summary
A complementary metal oxide semiconductor (CMOS) variable gain amplifier has a wider decibel-linear gain variation characteristic with respect to a control voltage when a signal is amplified. The variable gain amplifier includes: a bias input circuit for supplying a current corresponding to a bias voltage; an operation region combination and feedback circuit connected to the bias input circuit and combining at least two amplifiers by feedback in response to a control voltage, each amplifier having a decibel-linear characteristic in saturation and triode regions of a complementary metal oxide semiconductor (CMOS); and a bias output circuit connected to the bias input circuit, and outputting bias current controlled by the operation region combination and feedback circuit.