Auto Gain Control Circuit for Peak-Based Signal Amplitude Locking
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Solution Overview
Problem
Wireless communication systems using non-contact IC cards face challenges in maintaining signal amplitude consistency due to varying distances, leading to signal distortion and reduced receive sensitivity when using fixed gain amplifiers, as they either amplify signals beyond the operation range or fail to lock the auto gain controller without a preamble signal.
Innovation Solution
An auto gain controller with a variable gain amplification unit, peak detector, comparator, and voltage adjusting circuit that adjusts the auto gain control voltage and reference voltage based on detected peak values, allowing for dynamic gain adjustment and maintaining signal amplitude within a set range, enabling improved receiving performance across different communication modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a fixed gain amplifier with high gain value is used, then signal amplification is sufficient, but output signal exceeds operation range of analog to digital converter causing distortion
Solution Approach 1:
The patent implements a variable gain amplifier that dynamically adjusts its gain value based on the detected signal strength. The amplifier transitions from a fixed gain configuration to a dynamic gain control system where the gain value is modulated according to the input signal characteristics, thereby preventing output saturation while maintaining sufficient amplification for weak signals.
Solution Approach 2:
The patent employs a feedback mechanism where the output signal is monitored and fed back to control the gain of the amplifier. The controller detects the signal strength and adjusts the amplifier gain accordingly, creating a closed-loop system that automatically prevents output signal from exceeding the analog to digital converter's operation range while maintaining optimal signal levels.
2Reliability
If a fixed gain amplifier with low gain value is used, then output signal remains within operation range, but receive sensitivity of wireless communication system is deteriorated
Solution Approach 1:
The variable gain amplifier dynamically adjusts its gain value based on the detected signal strength. For weak incoming signals, the amplifier increases gain to maintain receive sensitivity, while for strong signals, it reduces gain to prevent output saturation. This dynamic adjustment resolves the contradiction between maintaining sensitivity and complying with signal range requirements.
Solution Approach 2:
The patent changes the gain parameter of the amplifier based on the input signal characteristics. By detecting signal strength and adjusting the gain parameter accordingly, the system maintains optimal receive sensitivity for weak signals while preventing output saturation for strong signals, thereby resolving the contradiction between sensitivity and range compliance.
3Extent of automation
If auto gain controller is used without preamble signal, then gain adjustment is automatic, but locking time is required which delays communication
Solution Approach 1:
The patent implements a self-service mechanism where the amplifier automatically adjusts its gain without requiring external control signals or preamble sequences. The system monitors its own output signal levels and autonomously modifies the gain setting, eliminating the need for time-consuming locking procedures and enabling immediate communication.
Solution Approach 2:
The patent extracts the gain control function from the traditional auto gain controller that requires preamble signals and locking time. By implementing a simplified automatic gain adjustment mechanism that operates independently of external control sequences, the system removes the time-consuming locking step while maintaining automatic gain adjustment capability.
4Reliability
If auto gain controller adjusts gain dynamically, then signal amplitude is maintained within range, but device complexity increases
Solution Approach 1:
The patent merges the gain control function with the existing amplifier structure, integrating the automatic gain adjustment capability into the amplifier itself rather than adding a separate complex control system. This consolidation maintains effective signal amplitude control while minimizing the increase in device complexity.
Solution Approach 2:
The patent implements a universal control mechanism that handles both gain adjustment and signal level monitoring functions within a single integrated system. The controller performs multiple functions including detecting signal strength, determining appropriate gain values, and adjusting the amplifier, thereby maintaining signal amplitude control without proportionally increasing device complexity.
Data Source
AI summary
An auto gain controller is provided. The auto gain controller includes a variable gain amplification unit configured to receive differential input signals, adjust an amplification gain based on an auto gain control voltage and output differential output signals. The auto gain controller also includes a peak detector configured to detect at least one peak value among the amplified differential output signals, a comparator configured to compare the at least one detected peak value with a reference voltage and generate a comparison signal, and a voltage adjusting circuit configured to adjust the auto gain control voltage and the reference voltage based on the comparison signal.