| The pyroelectric infrared(PIR) sensor absorbs the infrared radiation emitted from the human body and converts it into infrared signals to realize human body detection. The pyroelectric infrared detection controller chip produces valid output signal to drive the load by receiving the signals sent from the PIR sensor and processing it internally. Such chips in the market suffer from false triggering and great power consumption. In this thesis, we have done research in the analog and digital module of this chip. Circuit structures have been redesigned and key parameters have been optimized.(1)In design of the analog module, a compensation circuit of the two-stage operational amplifier driving a large external capacitive load is designed firstly to ensure the stable operation of operational amplifier. Secondly, an operational amplifier with high power rejection ratio is designed to resist interference. Thirdly, the low noise operational amplifier is optimized to reduce the inherent noise interference. Fourthly, the transfer function of the two-stage second-order bandpass filter amplifier circuit is analyzed to make a tradeoff between the sensitivity and noise immunity by changing the external resistors and capacitors.(2)In design of the digital module, the size of mos transistor is firstly optimized to reduce the total dynamic power dissipation. Secondly, the impact of different connections of the multi-input NOR gate and NAND gate to its dynamic power is analyzed and a low power consumption connection is optimized. Thirdly, the design principle of two different threshold of the Schmitt trigger is analyzed. Fourthly, the counter circuit is designed to acquire any integral multiple of the basic clock signal period. Fifthly, an anti-interference power-on reset circuit is designed.Finally, the overall circuit simulation is carried out. The circuit is well-functioning and achieves the design specifications for low power consumption and anti-interference. |
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