US 12,081,286 B2
Switch-mode power supply of a NFC type reader
Francois Agut, Saint Vital (FR); Severin Trochut, Gilly sur Isere (FR); and Vinko Kunc, Ljubljana (SI)
Assigned to STMICROELECTRONICS RAZVOJ POLPREVODNIKOV D.O.O., Ljubljana (SI); and STMICROELECTRONICS FRANCE, Montrouge (FR)
Filed by STMicroelectronics razvoj polprevodnikov d.o.o., Ljubljana (SI); and STMicroelectronics France, Montrouge (FR)
Filed on Sep. 30, 2019, as Appl. No. 16/587,419.
Claims priority of application No. 1859339 (FR), filed on Oct. 9, 2018.
Prior Publication US 2020/0112345 A1, Apr. 9, 2020
Int. Cl. H04B 5/00 (2024.01); G06K 19/07 (2006.01); G08C 17/02 (2006.01); H02M 3/335 (2006.01); H04B 5/24 (2024.01)
CPC H04B 5/24 (2024.01) [G06K 19/0725 (2013.01); G08C 17/02 (2013.01); H02M 3/33576 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A reader adapted to wirelessly exchanging information with a wireless apparatus, the reader comprising:
a signal generator configured to generate a modulation signal having a first state and a second state;
an emitter/receptor stage, wherein the modulation signal is representative of a variation of a load of the emitter/receptor stage; and
a switched-mode power supply configured to power the emitter/receptor stage, the switched-mode power supply comprising:
an input node configured to be coupled to a power source;
an inductor coupled between the input node and an intermediate node of the switched-mode power supply;
a power switch circuit between the intermediate node and a reference voltage node of the switched-mode power supply, the power switch circuit comprising a first switch and a first control circuit, wherein a first input terminal of the first control circuit is configured to be coupled to a first pulse-width-modulated (PWM) signal, a second input terminal of the first control circuit is configured to be coupled to the modulation signal, and a first output terminal of the first control circuit is coupled to a control terminal of the first switch, wherein the first control circuit is configured to generate, at the first output terminal, a first switching control signal by gating the first PWM signal with the modulation signal, wherein the first switch is configured to be switched on and off by the first switching control signal; and
a rectifier switch circuit between the intermediate node and an output node of the switched-mode power supply, the rectifier switch circuit comprising a second switch and a second control circuit, wherein a first input terminal of the second control circuit is configured to be coupled to a second PWM signal, a second input terminal of the second control circuit is configured to be coupled to the modulation signal, and a second output terminal of the second control circuit is coupled to a control terminal of the second switch, wherein the second control circuit is configured to generate, at the second output terminal, a second switching control signal by gating the second PWM signal with the modulation signal, wherein the second switch is configured to be switched on and off by the second switching control signal, wherein the second switch is configured to stay in an open state when the modulation signal is in the first state, wherein the second switch is configured to be switched on and off alternately when the modulation signal is in the second state.