Resistive-Matched Low-Noise Broadband Amplifier With Noise Cancellation
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Solution Overview
Problem
Traditional RF receiver signal chains face challenges in achieving reduced area and higher linearity in amplifier designs, particularly in matching input impedance and noise cancellation.
Innovation Solution
A passive mixer and noise-cancelling baseband amplifier circuit is implemented, utilizing resistors and amplifiers to achieve signal amplification while eliminating noise, with specific resistor ratios and amplifier configurations to optimize signal gain and suppress noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductors are used to match input impedance to the antenna, then impedance matching is achieved, but device area increases and linearity is reduced
Solution Approach 1:
The patent replaces the traditional inductor-based impedance matching network with a resistor-based matching circuit. Specifically, a first resistor is connected between the antenna and the first amplifier input, and a second resistor is connected between the antenna and the second amplifier input, eliminating the need for large inductors while achieving the same impedance matching function.
Solution Approach 2:
The patent changes the matching mechanism from reactive (inductive) to resistive by selecting specific resistor values. The first resistor has a value equal to the antenna impedance, and the second resistor has a value equal to twice the antenna impedance, creating a transformed impedance that achieves matching without requiring large inductor components.
2Power
If traditional amplifier configurations are used, then signal amplification is achieved, but noise from input resistors degrades performance
Solution Approach 1:
The patent converts the harmful noise from the second resistor into a beneficial signal by using a second amplifier to generate a canceling signal. The second amplifier is configured to produce an output that is the negative of the noise contribution from the second resistor, effectively canceling it out at the combined output.
Solution Approach 2:
The patent implements noise cancellation through a feedback mechanism where the second amplifier monitors and compensates for the noise generated by the second resistor. The feedback path ensures that the noise from the resistive matching network is actively canceled, allowing the use of resistors instead of inductors without sacrificing noise performance.
3Reliability
If resistive matching is implemented with noise cancellation, then linearity and area are improved, but device complexity increases
Solution Approach 1:
The patent merges the impedance matching function and the noise cancellation function into a unified resistive matching network with two amplifiers. The first amplifier handles the main signal path with the first resistor, while the second amplifier handles both the noise cancellation from the second resistor and contributes to the overall gain, combining multiple functions in a coordinated manner.
Data Source
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AI summary
Various circuitry may benefit from appropriate matching. For example, certain low noise broadband amplifiers may benefit from resistive matching.