Patent ID: 11893438
Assignee: EXCELIO TECHNOLOGY (SHENZHEN) CO., LTD.
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 0:
1. A positive feedback latch amplitude limiting control circuit of a passive radio frequency identification (RFID) tag, the circuit comprising: a signal generating circuit, a signal processing circuit and a discharge circuit, wherein:
the signal generating circuit is connected between an output terminal of a rectifier circuit and ground, and is configured to: generate a first control signal S1 that varies with change of strength of a magnetic field coupled to a coil of the passive RFID tag, input the first control signal S1 to the signal processing circuit and the discharge circuit, and receive a logic signal S2 returned by the signal processing circuit,
the signal processing circuit is connected between the output terminal of the rectifier circuit and the ground, and is configured to: receive the first control signal S1, latch the first control signal S1 to a high level or a low level according to a voltage amplitude of the first control signal S1, obtain the processed logic signal S2, and return the logic signal S2 to the signal generating circuit, and
the discharge circuit includes a MOS transistor whose gate voltage is indirectly controlled by a latch, and source and drain of the MOS transistor are respectively connected between the output terminal of the rectifier circuit and the ground, wherein: when the strength of the magnetic field coupled to the coil of the passive RFID tag is less than a preset value, the first control signal S1 is pulled down to the ground to maintain the discharge circuit in a turned-off state; when the strength of the magnetic field coupled to the coil of the passive RFID tag is greater than the preset value, the first control signal S1 is set to a high level to turn on the discharge circuit, and charges at the output terminal of the rectifier circuit are outputted to the ground; and an internal positive feedback latch mechanism of the latch makes the first control signal S1 have a substantially strong pull-down driving force when being pulled to a low level, such that a control gate of the discharge path is fully turned off, which avoids a discharge state of a sub-threshold region, and effectively reduces a leakage current in the discharge path, thereby achieving purposes of saving system power consumption and improving communication performance.