14443 interface BPSK subcarrier demodulation circuit

Abstract

The invention provides a BPSK subcarrier demodulation circuit of a 14443 interface PCD-end physical layer receiver. The circuit is mainly composed of an analog-to-digital converter, a subcarrier and bit synchronization circuit, a matching accumulator and a decision device. According to the circuit, the analog-to-digital converter is adopted for sampling a subcarrier signal, the amplitude information of the signal is retained, and the anti-interference ability of the circuit and the communication stability are improved through the use of a matching accumulation method in a digital domain.

Description

Technical field: [0001] The invention relates to the BPSK subcarrier demodulation technology of a 14443 interface PCD end physical layer receiver, which can be used for non-contact reader chip Type A212Kbps-848Kbps and Type B receivers. Background technique: [0002] In the field of non-contact smart cards, the communication system is divided into two parts: the reader (PCD) and the card (PICC). The physical layer signal returned by the PICC end through load modulation will inevitably introduce noise and interference. When these signals are demodulated and amplified by the RF carrier at the PCD end, the noise will be introduced into the subcarrier demodulation circuit of the next stage. Usually, the demodulation of the subcarrier is directly quantized into a logic 1 or 0 signal by a comparator and demodulated in the digital domain. [0003] After the subcarrier signal is quantized by the comparator, it is directly demodulated in the digital domain. The interference with a s...

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Problems solved by technology

[0003] After the subcarrier signal is quantized by the comparator, it is directly demodulated in the digital domain. The interference with a small amplitude will be quantized to the same high and low level as the useful signal, and the change of the width of the subcarrier signal will make it difficult to judge from the level width. Identify useful signals and interference, increase the difficulty of demodulation, and reduce the anti-interference ability of reception, resulting in error-prone communication and reduced communication efficiency

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