CMOS Resistive Feedback Amplifier With RC Feedback for Wideband Gain
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Solution Overview
Problem
Conventional resistive feedback amplifiers face challenges in achieving low Noise Figure, high gain, and low power consumption while maintaining broad bandwidth, as they often require a trade-off between gain and bandwidth, and exhibit inductive or capacitive input impedance at high frequencies, leading to reduced gain.
Innovation Solution
The implementation of a resistive feedback amplifier circuit using CMOS technology with a feedback impedance section that includes a resistor and capacitor, and a buffer section with a second-order response, which improves input reflection coefficient and gain across a wide frequency range without using inductors, thereby reducing production costs and die area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher transconductance gain is used to improve linearity and gain, then gain and linearity are improved, but current consumption increases
Solution Approach 1:
The patent changes the feedback impedance from purely resistive to a complex impedance with both resistive and capacitive components. This parameter change allows the feedback network to provide both gain enhancement and bandwidth extension without requiring proportionally higher current consumption, as the capacitive component contributes to impedance transformation and signal feedback efficiency.
2Adaptability or versatility
If higher frequency operation is implemented to achieve broad bandwidth, then bandwidth is improved, but current consumption increases to maintain sufficient gain
Solution Approach 1:
The feedback impedance is designed with a capacitive component that has frequency-dependent characteristics. This allows the feedback network to automatically adapt to higher frequency operations by providing appropriate impedance transformation and signal feedback, thereby achieving broad bandwidth without requiring excessive current consumption to maintain gain.
Solution Approach 2:
The complex feedback impedance network serves multiple functions simultaneously: it provides gain enhancement, bandwidth extension, and input impedance transformation. This multi-functionality allows the amplifier to achieve broad bandwidth across different frequency ranges without requiring separate circuits or significantly increased current consumption for each function.
3Power
If conventional resistive feedback is used to achieve high gain, then gain is improved, but bandwidth is limited and input impedance becomes inductive at high frequencies
Solution Approach 1:
The patent transforms the feedback impedance from purely resistive to complex (resistive + capacive). This parameter change fundamentally alters the frequency response characteristics, enabling the feedback network to maintain effective feedback across a broader frequency range. The capacitive component compensates for the inductive behavior of the input impedance at high frequencies, preventing gain plateau or decrease.
Solution Approach 2:
The capacitive component in the feedback impedance acts as an intermediary element that mediates between the resistive feedback path and the capacitive input impedance of the transistor. This intermediary capacitance helps transform the overall input impedance to remain resistive across a broader frequency range, thereby maintaining gain without the limitations of conventional resistive feedback.
4Reliability
If conventional resistive feedback amplifier is used to achieve low Noise Figure, then noise performance is improved, but the amplifier cannot simultaneously achieve high gain, large bandwidth, and low power consumption
Solution Approach 1:
By changing the feedback impedance from purely resistive to complex (with capacitive component), the patent achieves a more efficient feedback mechanism that simultaneously improves gain, bandwidth, and power efficiency while maintaining the low noise figure characteristic of resistive feedback amplifiers. The capacitive component enhances the overall performance without introducing significant noise.
Data Source
AI summary
Embodiments related to resistive feedback amplifiers are presented herein.