Input Buffer Biasing via DC Voltage Detection for Wider Dynamic Range
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Solution Overview
Problem
Existing signal processing circuits with AC coupled capacitors filter out DC voltage components to achieve a flat response in low-frequency bands, but this reduces the dynamic range of the signal path.
Innovation Solution
Incorporating a DC voltage detector circuit that detects the DC voltage of the input signal and generates a suitable bias for the input buffer circuit, allowing it to maintain a larger dynamic range without the need for AC coupled capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an AC coupled capacitor is disposed between the input terminal and the signal processing circuit to filter out DC voltage components, then the signal response in low-frequency parts is improved, but the dynamic range of the signal path is reduced
Solution Approach 1:
The patent extracts the DC voltage detection and bias adjustment functions from the traditional AC coupled capacitor approach. By using a DC voltage detector circuit to sense the DC component and an bias adjustor circuit to generate compensating bias voltage, the system removes the need for AC coupling capacitors while maintaining low-frequency response and preserving dynamic range.
Solution Approach 2:
The patent changes the operating parameters of the input buffer circuit by dynamically adjusting its bias voltage based on the detected DC component of the input signal. This parameter adjustment allows the circuit to compensate for DC offsets without requiring AC coupling, thereby maintaining both low-frequency response and full dynamic range.
2Measurement precision
If an AC coupled capacitor is used to filter DC voltage components, then low-frequency signal response is improved, but the circuit area and cost increase
Solution Approach 1:
The patent removes the physical AC coupling capacitors from the circuit architecture and extracts their DC blocking function into active circuit elements (DC voltage detector and bias adjustor). This elimination of passive capacitive components reduces the required circuit area while achieving the same low-frequency response improvement.
Solution Approach 2:
The patent replaces the passive mechanical/electrical AC coupling mechanism (capacitors) with an active electronic control system consisting of voltage detection and bias adjustment circuits. This substitution achieves the desired signal processing effect with smaller footprint components.
3Measurement precision
If an AC coupled capacitor is disposed in the signal path, then DC voltage components are filtered, but the overall system cost increases
Solution Approach 1:
The patent integrates multiple functions into the DC voltage detector and bias adjustor circuits. These circuits not only filter DC components but also provide adaptive biasing that optimizes the operating point of the input buffer, thereby achieving both DC rejection and performance optimization without requiring additional discrete components that would increase cost.
Solution Approach 2:
The patent merges the DC filtering function with the bias control function of the input buffer circuit. By combining these functions into integrated circuits rather than using separate AC coupling capacitors and bias networks, the overall system cost is reduced while maintaining the desired DC rejection capability.
Data Source
AI summary
A signal processing circuit includes an input buffer circuit and a direct-(DC) voltage detector circuit. The input buffer circuit is coupled to a pin. The pin is configured to receive an input signal. The DC voltage detector circuit is coupled to the pin and the input buffer circuit. The DC voltage detector circuit is configured to detect the input signal to generate a mode signal and generate a bias of the input buffer circuit according to the mode signal.