Clock recovery circuit used in non-contact IC card and radio frequency identification label

Abstract

The invention discloses a clock recovery circuit for non-contact type IC card and radio frequency identified tag chip, wherein one ends of two transfer gates are connected to the terminal end of the chip, the other ends of which are connected to the two input ends of a comparator, the signal outputted from the comparator is reshaped by a phase inverter and outputted from the output end as a clocksignal. The invention has a stable duty ratio and can be adaptable to the field density with wider range.

Description

technical field [0001] The invention relates to a clock recovery circuit, in particular to a clock recovery circuit for non-contact IC cards and radio frequency identification tag chips. Background technique [0002] In non-contact IC card and radio frequency identification tag products, the clock signal comes from the signal on the antenna. When this type of product is working, it may be very close to or far from the card reader. When the working distance is short, the field strength on the chip (card or label) is relatively large, and the peak signal on the antenna is very large; when the working distance is long, the field strength on the chip is relatively small, and the signal on the antenna The peak value is very small; if the field strength is relatively small and the chip is just in the load modulation state, the signal peak value on the antenna is even smaller. The clock of the chip needs to be recovered from the antenna signal, which brings difficulties to the c...

AI Technical Summary

Problems solved by technology

This circuit structure adapts to a narrow range of field strength, especially for relatively small antenna signals, it is difficult to recover the clock signal; moreover, the duty cycle of the recovered clock signal will vary greatly with the change of field strength. Variety

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