Switchable Inductor VGA Topology for Constant Bandwidth
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Solution Overview
Problem
Conventional variable gain amplifiers (VGAs) face inadequacies in achieving optimal linearity and bandwidth, leading to unintended peaking and bandwidth extension, which affect the performance of analog-to-digital converter systems and create challenges in equalization systems that require constant bandwidth.
Innovation Solution
The proposed solution involves a variable gain amplifier design that includes a first switch with a drain terminal coupled to an inductor, a second switch configured in parallel to the inductor with adjustable resistance in response to a control signal, and additional switches and inductors to maintain constant bandwidth and linearity across a large gain control range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional variable gain amplifier designs are used, then gain control range is achieved, but bandwidth variation and peaking occur
Solution Approach 1:
The patent applies dynamics by making the amplifier circuit configurable through multiple switches (first switch, second switch, third switch, fourth switch) that can be activated or deactivated based on control signals. This dynamic reconfiguration allows the amplifier to adjust its gain while maintaining constant bandwidth, as the switches enable different circuit topologies to be realized without changing the overall bandwidth characteristics of the amplifier.
Solution Approach 2:
The patent segments the amplifier circuit into multiple parallel paths with different gain characteristics. By dividing the circuit into segments controlled by individual switches, the system can selectively activate specific paths to achieve desired gain levels while maintaining constant bandwidth. The segmentation allows independent control of gain without affecting bandwidth stability.
2Adaptability or versatility
If conventional variable gain amplifier designs are used, then gain adjustment is possible, but linearity deteriorates
Solution Approach 1:
The patent changes circuit parameters by reconfiguring the amplifier topology through switch control. Different switch combinations alter the effective circuit parameters (such as feedback ratios and gain settings) while maintaining linear operation. This parameter change approach allows gain adjustment without sacrificing linearity, as each configured state is designed to operate in the linear region.
3Speed
If bandwidth extension is achieved in conventional VGAs, then frequency range increases, but unintended peaking occurs
Solution Approach 1:
The patent converts the potential harmful effect of bandwidth extension (which typically causes peaking) into a benefit by carefully designing the circuit configuration. Through specific switch arrangements and circuit topologies, the amplifier achieves extended bandwidth while the peaking effect is eliminated or controlled. The circuit design transforms what would normally be a harmful artifact into an acceptable or even desirable characteristic.
Data Source
AI summary
The present invention is directed electrical circuits. According to a specific embodiment, the present invention provides a variable gain amplifier that includes a first switch, which includes drain terminal coupled to an inductor. A second switch is configured in parallel to the inductor, and the resistance value of the second switch is adjustable in response to a control signal. There are other embodiments as well.