Delta-Sigma Pen Signal Detection With Adaptive Feedback Gain
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Solution Overview
Problem
Conventional delta-sigma modulation circuits are impractical for detecting pen signals due to their large size and cost, as they require a multibit configuration to handle the dynamic range of pen signals, and the feedback signal level does not follow the input signal level, leading to undetectable pen signals.
Innovation Solution
An integrated circuit with a delta-sigma modulation circuit that includes a subtractor, integrator, quantizer, and digital analog converter, along with a gain controller to adjust the feedback signal level based on the detected pen signal level, allowing the circuit to detect pen signals without a multibit quantizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multibit quantizer configuration is used to handle the dynamic range of pen signals, then the detection accuracy of pen signals is improved, but the device size and manufacturing cost increase significantly
Solution Approach 1:
The patent implements automatic gain control (AGC) that dynamically adjusts the feedback signal level based on the detected input signal level. The gain controller continuously monitors the input signal and adjusts the feedback signal amplitude accordingly, allowing a single-bit quantizer to effectively track signals across a wide dynamic range without requiring multiple comparators.
Solution Approach 2:
The patent employs a feedback mechanism where the output of the single-bit quantizer is fed back through a digital-to-analog converter (DAC) and summed with the input signal. This feedback loop, combined with automatic gain control, enables the system to maintain proper signal levels and detect pen signals accurately using only one comparator instead of many.
2Device complexity
If the feedback signal level is kept constant in a delta-sigma modulation circuit, then the circuit structure is simplified, but the pen signal becomes undetectable when the signal level exceeds the feedback signal level
Solution Approach 1:
The patent transforms the static feedback signal level into a dynamic one by introducing automatic gain control. The feedback signal level now automatically adapts to match the input signal level, ensuring that the subtractor continues to produce oscillating output signals even when the pen signal amplitude varies widely, thus maintaining detectability across all signal levels.
Data Source
AI summary
A delta-sigma modulation circuit is enabled to be used to detect a pen signal. An integrated circuit according to the present disclosure is a sensor controller that detects pen signals transmitted from an active pen. The integrated circuit includes a delta-sigma modulation circuit including a subtractor that subtracts a feedback signal from a received signal input from a sensor, an integrator that integrates an output signal of the subtractor, a quantizer that quantizes an output signal of the integrator, and a digital analog converter that generates the feedback signal based on an output value of the quantizer. The integrated circuit also has a processor that detects a level of the received signal based on an output value of the delta-sigma modulation circuit, and a gain controller that a level of the feedback signal based on the level of the received signal detected by the processor.