Circuits and systems for low power magnetic secure transmission

Patent metadata

Field	Value
Publication number	US-10699175-B2
Application number	US-201916367189-A
Country	US
Kind code	B2
Filing date	Mar 27, 2019
Priority date	Aug 29, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

According to another embodiment, a system includes a driver circuit that drives a first output and a second output; a coil coupled between the first output and the second output such that the driver circuit drives current through the coil in response to control signals; and a programmable slew circuit coupled to the driver circuit. In some embodiments, a switch is coupled between the first output and the coil. In some embodiments an over-voltage protection circuit is coupled to protect the driver circuit.

First claim

What is claimed is:

1. A driver circuit for an inductor, the circuit comprising:
a first switch for coupling an input voltage to a first lead of an inductor;
a second switch for coupling the input voltage to a second lead of the inductor;
a third switch coupled between the first lead of the inductor and ground;
a fourth switch coupled between the second lead of the inductor and ground;
a first amplifier for controlling the third switch based on a first current through the third switch and a first reference current;
a second amplifier for controlling the fourth switch based on a second current through the fourth switch and a second reference current; and
a controller for controlling the first switch, the second switch, the first reference current, and the second reference current.

2. The circuit of claim 1 , further comprising:
a series combination of a first resistor and a fifth switch connected in parallel with the third switch; and
a series combination of a second resistor and a sixth switch connected in parallel with the fourth switch;
wherein:
the fifth switch is controlled by the first amplifier; and
the sixth switch is controlled by the second amplifier.

3. The circuit of claim 1 , wherein the controller is further configured to:
ramp the first reference current and the second reference current during polarity changes in a current through the inductor; and
stagger the ramping of the first threshold and the second threshold relative to each other.

Assignees

• Integrated Device Tech

Inventors

• Liu Rui
• Qi Tao
• Zhao Lijie
• Mehas Gustavo James
• Park Tae Kwang
• Guo Zhitong
• Fan Siqiang

Classifications

• G06K19/07779

  the inductive antenna being a coil · CPC title

• G06K19/06206 Primary

  the magnetic marking being emulated · CPC title

• G06K7/10316

  using at least one antenna particularly designed for interrogating the wireless record carriers (antennas in general H01Q1/22) · CPC title

• G06K7/084

  sensing magnetic material by relative movement detecting flux changes without altering its magnetised state · CPC title

• G06Q20/3278

  RFID or NFC payments by means of M-devices · CPC title