Frequency self-adaptive circuit of non-contact intelligent card chip

Abstract

The invention provides a frequency self-adaptive circuit of a non-contact intelligent card chip. The frequency self-adaptive circuit comprises an amplitude limiting circuit, a bypass current samplingcircuit, a current-voltage-current conversion circuit and a ring oscillator. The amplitude limiting circuit is sequentially connected with the bypass current sampling circuit, the current-voltage-current conversion circuit and the ring oscillator, the ring oscillator is newly added, and the output frequency of the ring oscillator is controlled through a field intensity signal to achieve the frequency self-adaption function. Meanwhile, the bypass current sampling circuit is newly added, the bypass current in the amplitude limiting circuit is used as a field intensity indication signal, the linear range of control over the output frequency of the ring oscillator is expanded through the current-voltage-current conversion circuit, and the linearity and smoothness of system frequency to field intensity self-adaptive conversion are improved. Compared with a traditional non-contact card system, when the field intensity of a card changes, the switching speed of the operating frequency of the system is higher, more linear and more continuous; and the hardware implementation cost is lower, and the power consumption is lower.

Description

technical field [0001] The invention relates to the technical field of integrated circuit non-contact smart cards, in particular to a frequency adaptive circuit of a non-contact smart card chip. Background technique [0002] In high-frequency contactless smart card applications, the card obtains energy from the card reader through inductive coupling. The greater the coupling coefficient, the greater the energy the card gets and the faster it runs. Conversely, the smaller the coupling coefficient, the smaller the energy the card gets, and the slower the running speed. If the running speed of the card does not match the obtained energy, it will lead to energy waste or power-off reset. This technology is called Frequency Adaptive (FA) in the design of contactless smart card chips. A good frequency adaptive technology has the characteristics of fast response speed, smooth frequency, and low hardware overhead. [0003] In the existing non-contact card frequency self-adaptive c...

AI Technical Summary

Problems solved by technology

[0004] However, the frequency adaptive circuit of the existing contactless card has problems such as complex system structure, large power consumption, slow response time, and uneven frequency switching. At the same time, there is also the problem that the energy utilization efficiency is not high enough.

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