Bounded Pre-Filter AGC in Cascaded Narrowband Filter Circuits
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Solution Overview
Problem
Conventional automatic gain control (AGC) pre and post filter arrangements in narrowband filter circuits do not distribute gains optimally, leading to suboptimal signal processing and potential clipping or distortion due to perturbations in adjacent channels.
Innovation Solution
The implementation of a cascaded filter configuration with variable gain amplifiers and separate AGC blocks that form and bound gain control signals to control the amplifiers, ensuring that the gain of the first amplifier is limited by a signal containing information filtered by subsequent filters, thereby reducing the impact of adjacent channel perturbations and preventing clipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AGC pre and post filter arrangements are used, then the filter input and output can be maintained within desired ranges, but the AGC gains are not distributed optimally leading to suboptimal signal processing and potential clipping
Solution Approach 1:
The patent divides the AGC control into separate pre-filter and post-filter control blocks, with the pre-filter AGC further segmented into multiple gain control stages. This segmentation allows independent optimization of gain distribution at different stages, improving signal processing quality while managing complexity through modular design.
Solution Approach 2:
The patent applies preliminary gain control before the signal enters the filter by using a pre-filter AGC block that processes the input signal beforehand. This preliminary action prevents clipping and distortion by controlling the gain at the input stage, avoiding the need for complex post-correction and improving overall signal processing quality.
2Power
If the first amplifier gain is increased to amplify weak signals, then signal strength is improved, but clipping or distortion occurs due to perturbations in adjacent channels
Solution Approach 1:
The patent applies preliminary anti-action by using the pre-filter AGC block to anticipate and counteract potential clipping or distortion before they occur. The pre-filter AGC controls the gain of the first amplifier based on predicted signal characteristics, preventing harmful effects from occurring in the first place rather than correcting them afterward.
Solution Approach 2:
The patent implements feedback mechanisms where the post-filter AGC block receives information about the filtered signal and adjusts the pre-filter AGC accordingly. This feedback loop allows the system to adapt gain control based on actual signal characteristics, maintaining optimal signal strength while preventing clipping and distortion from adjacent channel perturbations.
Data Source
AI summary
An electronic circuit includes a first variable gain amplifier for amplifying a signal at an input to provide a first amplified signal; a filter receiving the first amplified signal to provide a filtered signal; a second variable gain amplifier for receiving and amplifying the filtered signal; a second gain control bock, to provide at least one gain control signal derived from the filtered signal, one of the at least one gain control signal to control the gain of the second variable gain amplifier; and a bounding block for receiving one of the at least one gain control signal from the second gain control block, and for generating therefrom a bounded gain control signal to control gain of the first variable gain amplifier.