LED transceiver front end circuitry and related methods
First Claim
1. An apparatus for transmitting and receiving light, comprising:
- current source circuitry coupled to an LED and configured to force a first current through the LED to produce light during a transmit state;
control circuitry coupled to the LED and configured to apply a controlled voltage across the LED during a receive state, wherein the control circuitry comprises switch circuitry configured to couple an anode of the LED to a power supply voltage in the transmit state and to couple the anode of the LED to near ground in the receive state; and
measurement circuitry coupled to the LED and configured to measure a second current induced in the LED by incident light during the receive state.
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Accused Products
Abstract
LED transceiver front end circuitry and related methods are disclosed that use an LED or LEDs to transmit light in a transmit state and to receive incident light in a receive state while helping to reduce effects of power supply noise and ripple and device leakage currents on incident light measurements in applications where such conditions exist. In the disclosed embodiments and implementations, a controlled voltage is applied across an LED or LEDs or a reference voltage is applied to an LED chain or LED to help reduce the effects of power supply noise and ripple and device leakage currents on incident light measurements during a receive state of operation. Further, with respect to the LED chain, one or more resistors are coupled in parallel to the LEDs in the LED chain.
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Citations
34 Claims
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1. An apparatus for transmitting and receiving light, comprising:
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current source circuitry coupled to an LED and configured to force a first current through the LED to produce light during a transmit state; control circuitry coupled to the LED and configured to apply a controlled voltage across the LED during a receive state, wherein the control circuitry comprises switch circuitry configured to couple an anode of the LED to a power supply voltage in the transmit state and to couple the anode of the LED to near ground in the receive state; and measurement circuitry coupled to the LED and configured to measure a second current induced in the LED by incident light during the receive state. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for transmitting and receiving light, comprising
an LED chain, the LED chain comprising one or more serially connected LEDs with at least one LED in the LED chain coupled in parallel with a resistor; -
current source circuitry coupled to the LED chain and configured to force a first current through the LED chain to produce light during a transmit state; control circuitry coupled to the LED chain and configured to apply a reference voltage to the LED chain during a receive state; and measurement circuitry coupled to the LED chain and configured to measure a voltage induced in the LED chain by incident light during the receive state; and wherein the control circuit is further configured to vary the reference voltage based upon a measurement of the voltage induced in the LED chain by incident light during the receive state. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A method for transmitting and receiving light, comprising:
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forcing a first current through an LED to produce light during a transmit state by coupling an anode of the LED to a power supply voltage in the transmit state; applying a controlled voltage across the LED during a receive state by coupling the anode of the LED to ground in the receive state; and measuring a second current induced in the LED by incident light during the receive state. - View Dependent Claims (15, 16, 17, 18)
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19. A method for transmitting and receiving light, comprising
forcing a first current through an LED chain to produce light during a transmit state, the LED chain comprising one or more LEDs with at least one LED in the LED chain coupled in parallel with a resistor; -
applying a reference voltage to the LED chain during a receive state; measuring a voltage induced in the LED chain by incident light during the receive state; and varying the reference voltage based upon the measuring step. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. An apparatus for transmitting and receiving light, comprising:
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current source circuitry coupled to an LED and configured to force a first current through the LED to produce light during a transmit state; control circuitry coupled to the LED and configured to apply a controlled voltage across the LED during a receive state, wherein the control circuitry comprises switch circuitry configured to couple an anode of the LED to a power supply voltage in the transmit state and not to couple the anode of the LED to the power supply voltage in the receive state; and measurement circuitry coupled to the LED and configured to measure a second current induced in the LED by incident light during the receive state. - View Dependent Claims (28, 29, 30, 31)
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32. A method for transmitting and receiving light, comprising:
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forcing a first current through an LED to produce light during a transmit state by coupling an anode of the LED to a power supply voltage in the transmit state; applying a controlled voltage across the LED during a receive state by not coupling the anode of the LED to the power supply voltage in the receive state; and measuring a second current induced in the LED by incident light during the receive state. - View Dependent Claims (33, 34)
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Specification