Mirrored Baseband Current AGC for RF Front-End Compression
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Solution Overview
Problem
Direct-conversion RF receivers face front-end compression due to interfering signals outside the narrow band, making it difficult to reliably receive and decode the channel of interest without detecting the cause of compression.
Innovation Solution
A system with an RF receiver configured to convert wideband RF signals to wideband baseband current signals, using a current replicator to generate a mirrored current, which is then measured by a wideband signal-level detector to adjust the receiver's gain automatically through an AGC circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver processes only narrowband baseband voltage signals tuned to the channel of interest, then the demodulation stage can efficiently decode the desired signal, but the receiver cannot detect interfering signals outside the narrow band causing front-end compression
Solution Approach 1:
The patent segments the signal processing path into two parallel branches: a narrowband path for demodulating the channel of interest and a wideband path for detecting interfering signals. The wideband baseband current signal is split from the main processing path to feed both the demodulation stage and the signal-level detector, enabling independent processing of desired and interfering signals without increasing overall system complexity
Solution Approach 2:
The patent introduces a wideband signal-level detector as an intermediary component that monitors the wideband baseband current signal to detect front-end compression caused by interfering signals. This detector acts as an early warning system that provides feedback to the AGC circuit, allowing the receiver to adjust gain before the interfering signals cause harmful compression effects in the narrowband demodulation path
2Adaptability or versatility
If the receiver uses automatic gain control to maintain optimal signal levels, then the receiver can adapt to varying signal strengths, but the AGC cannot respond to front-end compression caused by interfering signals outside the narrow band
Solution Approach 1:
The patent implements a feedback mechanism where the wideband signal-level detector continuously monitors the wideband baseband current signal and provides feedback to the AGC circuit. When the detector identifies signal levels indicating front-end compression from interfering signals, it triggers the AGC to adjust the receiver gain, creating a closed-loop control system that adapts to both desired signal strength variations and harmful interfering signal conditions
Solution Approach 2:
The patent performs preliminary detection of front-end compression by monitoring the wideband baseband current signal before it enters the narrowband demodulation stage. The signal-level detector identifies interfering signals and compression conditions in advance, allowing the AGC to preemptively adjust gain to prevent harmful compression effects from occurring in the main signal path
3Object-affected harmful factors
If the receiver processes wideband RF signals to capture all component signals, then the receiver can detect interfering signals, but the processing complexity and computational load increase significantly
Solution Approach 1:
The patent extracts only the necessary information from the wideband baseband current signal for interference detection purposes. Instead of fully processing all wideband component signals through complex demodulation algorithms, the system extracts signal level information from the wideband current and feeds it to a simplified signal-level detector, achieving interfering signal detection with minimal processing complexity
Data Source
AI summary
Disclosed herein are systems for and methods of using a mirrored wideband baseband current for automatic gain control of an RF receiver. In an embodiment, a system includes an RF receiver having an adjustable gain and being configured to direct convert a received wideband RF signal to a wideband baseband current signal. The system further includes a current replicator coupled to the receiver and configured to generate a mirrored current of the wideband baseband current signal. The system further includes a wideband signal-level detector configured to receive the mirrored current from the current replicator, and to measure and output a signal-level value of the mirrored current. The system further includes an automatic gain-control circuit configured to receive the signal-level value from the wideband signal-level detector, and to adjust the gain of the receiver based at least in part on the received signal-level value.