Automatic calibration SWP slave interface circuit

Abstract

The invention provides an automatic calibration SWP slave interface circuit. The SWP slave interface circuit comprises an electrostatic protection circuit, a receiving circuit, a transmitting circuitand a reference current generating circuit, the electrostatic protection circuit is connected with the receiving circuit, the receiving circuit is connected with the transmitting circuit, and the transmitting circuit is connected with the reference current generating circuit. According to the automatic calibration SWP slave interface circuit, afirst digital control circuit and areference current source generation circuit are introduced, the load modulation degree when the SWP slave interface transmits a voltage signal can be automatically calibrated, load debugging of each chip is avoided, theproduction period is shortened, and the production cost is reduced; and the automatic calibration SWP slave interface circuit is simple in structure and easy to integrate.

Description

technical field [0001] The invention relates to the technical field of integrated circuits in large-capacity SIM card interface technology, in particular to an automatic calibration SWP slave interface circuit. Background technique [0002] In recent years, the mobile phone is no longer a simple communication device, it has become a portable entertainment and payment device, among which mobile payment plays an irreplaceable role in shopping, medical care, communication, banking and other fields. There are many mobile payment solutions, among which SIM SWP (Single Wire Protocol) interface is connected to NFC chip to realize point-to-point communication is a relatively feasible solution, such as figure 1 Shown is a block diagram of the existing SWP interface circuit data transmission. Wherein, the SWP interface circuit realizes full-duplex communication on a single wire, that is, the first digital modulation signal S1 in the voltage domain and the second digital modulation si...

AI Technical Summary

Problems solved by technology

[0005] 1. Generally, the reference current IREF is relatively small, usually below 1uA, which makes the magnification of the current amplification circuit between 600 times and 1000 times, but the above-mentioned current amplifying circuit, the magnification is difficult to accurately control, resulting in the current signal S2 not meeting SWP Protocol Requirements

[0006] 2. In order to make the current signal S2 meet the requirements of the SWP protocol, load debugging is usually performed on each SWP SIM chip, which takes time and effort and increases production costs

Images