Bidirectional Signal Detection Circuit for Pyroelectric Infrared Sensors
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Solution Overview
Problem
Existing signal detection circuits for pyroelectric infrared detection elements require increased circuit size and current consumption to detect changes in voltage signals on both positive and negative sides, leading to inefficiencies.
Innovation Solution
A signal detection circuit incorporating a p-channel MOS transistor, n-channel MOS transistors, and current-voltage conversion circuits to amplify changes in signal voltages on both positive and negative sides, reducing circuit size and current consumption while maintaining detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate detection circuits are used for positive and negative voltage changes, then detection capability is improved, but circuit size and current consumption increase
Solution Approach 1:
The patent combines both positive and negative voltage change detection functions into a single integrated circuit. The circuit uses a single n-channel MOS transistor that can respond to both upward and downward voltage changes by appropriately configuring the resistor connections and signal processing paths, thereby eliminating the need for separate detection circuits and reducing overall circuit size.
Solution Approach 2:
The detection circuit is designed with multi-functional capability where the same circuit components serve dual purposes. The n-channel MOS transistor and associated resistors are configured to detect both positive and negative voltage variations through different signal paths, making the circuit universal for bidirectional voltage change detection rather than requiring specialized circuits for each direction.
2Measurement precision
If separate detection circuits are used for positive and negative voltage changes, then detection capability is improved, but current consumption increases
Solution Approach 1:
The patent merges the detection functions for positive and negative voltage changes into a single circuit operation. By using one MOS transistor with properly configured resistor networks, the circuit processes both types of voltage changes through unified signal paths, thereby halving the current consumption compared to having two separate detection circuits operating simultaneously.
3Device complexity
If a simple detection circuit is used, then circuit size is reduced, but detection accuracy for bidirectional voltage changes deteriorates
Solution Approach 1:
The patent applies local quality by creating asymmetric circuit configurations tailored for detecting specific voltage change directions. The resistor connections are locally optimized - with one resistor connected to the gate and another to the drain - to enhance sensitivity for positive voltage changes, while the same circuit structure inherently provides detection capability for negative changes through complementary signal paths, thus achieving directional detection optimization within a compact circuit.
Data Source
AI summary
A signal detection circuit includes: a power terminal; a first current limitation circuit; a second current limitation circuit; a current-voltage conversion circuit; a first p-channel MOS transistor including a source, a gat, and a drain; a first n-channel MOS transistor including a drain, a gate, and a source; and a second n-channel MOS transistor in which a drain is connected to a first connection point connecting the resistor with the drain of the first n-channel MOS transistor, a gate is connected to a second connection point connecting the drain of the first p-channel MOS transistor with the current-voltage conversion circuit, and a source is grounded.