Variable-Gain Low Noise Amplifier With Phase Matching Circuit
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Solution Overview
Problem
Existing low noise amplifiers face challenges in maintaining a small phase difference between outputs of amplifier blocks with varying gain values, particularly between passive attenuators and positive gain amplifiers, complicating the design of RF receivers.
Innovation Solution
A phase difference matching circuit is added to the output terminal of an attenuator in a low noise amplifier with a variable gain switching structure, accompanied by a variable impedance circuit to finely adjust phase differences, ensuring consistent phase across multiple gain modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable gain switching structure with multiple amplifier blocks is used to handle a wide range of power levels, then the power level response capability is improved, but the phase difference between outputs of amplifier blocks with different gain values increases
Solution Approach 1:
A phase difference matching circuit is introduced as an intermediary component between the attenuator and the output terminal. This matching circuit compensates for the phase difference introduced by the attenuator, ensuring that the output phase in attenuation mode matches the output phase in amplification mode, thereby resolving the phase inconsistency problem across different gain modes
Solution Approach 2:
The patent introduces a variable impedance circuit that can dynamically adjust impedance parameters to compensate for phase differences. By changing the impedance parameters in response to different gain modes, the system maintains consistent phase characteristics across varying power levels and gain configurations
2Manufacturing precision
If software-sampled input signal delay control is applied to solve phase difference problems, then the phase difference between attenuator and amplifier outputs is reduced, but the receiver design complexity increases due to required signal connection
Solution Approach 1:
Instead of using software-based delay control that requires complex signal connections, the patent introduces a hardware-based phase difference matching circuit as an intermediary. This circuit directly compensates for phase differences in the signal path, eliminating the need for software sampling and complex receiver design while achieving the same phase alignment objective
3Adaptability or versatility
If an attenuator with negative gain is used instead of a positive gain amplifier, then the gain range is extended to include negative values, but the phase difference between attenuator and amplifier outputs increases
Solution Approach 1:
A phase difference matching circuit is placed at the output of the attenuator to compensate for the phase inversion characteristic of attenuation. This intermediary circuit ensures that even though the attenuator introduces a phase difference, the final output phase matches that of the positive gain amplifier, allowing the system to maintain extended gain range while preserving phase consistency
Data Source
AI summary
Disclosed is a technology related to a low noise amplifier applied between an RF receiver and an RF switch. A phase difference matching circuit having the same phase difference as a positive gain amplifier is added to an output terminal of an attenuator of a low noise amplifier having a variable gain switching structure. In addition, a variable impedance circuit connected to an output terminal of the positive gain amplifier and an output terminal of a phase difference matching unit to finely adjust the phase difference of each output terminal may be further included.