Feedback control loop for NFC transmitter voltage control
First Claim
1. A payment object reader that is configured to read data from payment objects using a near field communication (NFC) protocol, the payment object reader comprising:
- a NFC antenna configured to modulate a magnetic field to read data from a NFC-enabled payment object;
a boost converter integrated circuit (IC) chip having a voltage output pin connected to the NFC antenna, and a feedback pin connected to a first feedback circuit, the boost converter IC chip configured to regulate a first voltage provided to the NFC antenna to modulate the magnetic field;
the first feedback circuit connected at a first terminal to the NFC antenna, and connected at a second terminal to the feedback pin of the boost converter IC chip, whereby the boost converter IC chip monitors the first voltage at the NFC antenna;
a second feedback circuit comprising a microcontroller having an analog-to-digital converter (ADC) input, and a digital-to-analog converter (DAC) output, the ADC input connected to the NFC antenna, and the DAC connected to the feedback pin of the boost converter IC chip by a line having a transistor and a resistor divider therein; and
whereby the second feedback circuit is configured to feed an antenna voltage from the NFC antenna to the microcontroller through the ADC input, and the microcontroller can control the DAC output to the transistor based on the antenna voltage from the NFC antenna, in this manner the microcontroller is configured to control an amount of power provided to the NFC antenna by the boost converter IC chip such that the boost converter IC chip can be controlled to output an output voltage selected from a set of voltages including the first voltage and a second voltage as determined by the microcontroller, and the microcontroller is configured to account for factors affecting accuracy of the second voltage caused by signal drift from a desired output signal value due to temperature effects at the transistor.
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Accused Products
Abstract
A payment object reader configured to read data from NFC or EMV enabled payment objects. The payment device includes a NFC antenna, a boost converter (voltage regulator) chip. A first feedback circuit is connected to the NFC antenna and the feedback pin of the boost converter chip. The boost converter chip regulates a first voltage provided to the NFC antenna for the NFC antenna to modulate a field. A second feedback circuit includes a microcontroller with an ADC input and a DAC output. ADC input is connected to NFC antenna, and DAC is connected to the feedback pin of the boost converter chip. The microcontroller receives the voltage at the ADC input and controls the DAC output to transition based on the value of the ADC input.
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Citations
22 Claims
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1. A payment object reader that is configured to read data from payment objects using a near field communication (NFC) protocol, the payment object reader comprising:
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a NFC antenna configured to modulate a magnetic field to read data from a NFC-enabled payment object; a boost converter integrated circuit (IC) chip having a voltage output pin connected to the NFC antenna, and a feedback pin connected to a first feedback circuit, the boost converter IC chip configured to regulate a first voltage provided to the NFC antenna to modulate the magnetic field; the first feedback circuit connected at a first terminal to the NFC antenna, and connected at a second terminal to the feedback pin of the boost converter IC chip, whereby the boost converter IC chip monitors the first voltage at the NFC antenna; a second feedback circuit comprising a microcontroller having an analog-to-digital converter (ADC) input, and a digital-to-analog converter (DAC) output, the ADC input connected to the NFC antenna, and the DAC connected to the feedback pin of the boost converter IC chip by a line having a transistor and a resistor divider therein; and whereby the second feedback circuit is configured to feed an antenna voltage from the NFC antenna to the microcontroller through the ADC input, and the microcontroller can control the DAC output to the transistor based on the antenna voltage from the NFC antenna, in this manner the microcontroller is configured to control an amount of power provided to the NFC antenna by the boost converter IC chip such that the boost converter IC chip can be controlled to output an output voltage selected from a set of voltages including the first voltage and a second voltage as determined by the microcontroller, and the microcontroller is configured to account for factors affecting accuracy of the second voltage caused by signal drift from a desired output signal value due to temperature effects at the transistor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A payment object reader comprising:
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a microcontroller having an analog-to-digital converter (ADC) input and a digital-to-analog converter (DAC) output; a line having a transistor and a resistor divider therein, the line connected at a first end to the DAC output of the microcontroller, the line connected at a second end to a feedback pin of a boost converter integrated circuit (IC) chip to complete a feedback loop associated with the boost converter IC chip; and a non-transitory computer readable medium having instructions stored thereon that when executed are effective to cause the microcontroller to; receive, at the ADC input of the microcontroller, a first voltage provided by the boost converter integrated circuit (IC) chip to a payment object reader interface that is configured to read payment data from a payment object; and control the DAC output of the microcontroller that is coupled to the feedback pin of the boost converter IC chip via the line having the transistor and the resistor divider therein, the DAC output controlling an amount of power output by the boost converter IC chip to the payment object reader interface based on the ADC input, such that the amount of power output by the boost converter IC chip to the payment object reader interface is an output voltage selected from a set of voltages including the first voltage and a second voltage as determined by the microcontroller wherein the microcontroller is configured to account for factors affecting accuracy of the second voltage caused by signal drift from a desired output signal value due to temperature effects at the transistor. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method of controlling an output of a boost converter chip, the method comprising:
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monitoring a first voltage at a near field communication (NFC) antenna connected to a first feedback circuit, the NFC antenna connected to the boost converter chip that is configured to regulate the first voltage provided to the NFC antenna, the NFC antenna configured to read data from a NFC-enabled payment object; feeding the first voltage from the NFC antenna to a second feedback circuit, wherein the second feedback circuit is configured to feed the first voltage from the NFC antenna to a microcontroller of the second feedback circuit through an analog-to-digital converter (ADC) input of the microcontroller; and controlling a digital-to-analog converter (DAC) output of the microcontroller that is coupled to a feedback pin of the boost converter chip, to thereby cause the boost converter chip to output an output voltage to the NFC antenna based on the ADC input, the output voltage selected from a set of voltages including the first voltage and a second voltage determined by the microcontroller. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification