Methods and apparatuses for receiving and transmitting signals
First Claim
1. A transceiver for driving and receiving a signal through a transformer comprising:
- an FET power transistor having an output contact for conducting current to a coil of a transformer, said power transistor having a control gate with a parasitic capacitance;
a gate drive circuit which provides a controlled current flow to and from the gate so as to charge and discharge the gate and its parasitic capacitance, and so as to increase and decrease, respectively, the output current supplied by the output of the power transistor at a controlled rate;
wherein said drive circuit controls said current flow by causing a voltage level that drives such current to compensate for changes in the voltage on the gate so as to make the rate at which such current flows substantially constant during said charging and discharging.
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Accused Products
Abstract
Circuitry for transmitting signals through a transformer has an output transistor and circuitry which provides a controlled current to and from the output transistor'"'"'s gate, so as to charge and discharge the gate'"'"'s parasitic capacitance and increase and decrease the transistor'"'"'s output current in a controlled manner. Feedback can be used to sense an output signal created by the transistor and turn off current to or from the transistor'"'"'s gate when the output signal has reached a desired level. The output signal can be the voltage differential produced across an output transformer, and, where the output transformer is center-tapped, it can be the voltage differential across both halves of the center tapped winding.
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Citations
49 Claims
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1. A transceiver for driving and receiving a signal through a transformer comprising:
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an FET power transistor having an output contact for conducting current to a coil of a transformer, said power transistor having a control gate with a parasitic capacitance; a gate drive circuit which provides a controlled current flow to and from the gate so as to charge and discharge the gate and its parasitic capacitance, and so as to increase and decrease, respectively, the output current supplied by the output of the power transistor at a controlled rate; wherein said drive circuit controls said current flow by causing a voltage level that drives such current to compensate for changes in the voltage on the gate so as to make the rate at which such current flows substantially constant during said charging and discharging. - View Dependent Claims (2, 3, 4, 5)
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6. An output circuit for driving a signal comprising:
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an FET power transistor having an output contact, said power transistor having a control gate with a parasitic capacitance; a gate drive circuit that provides a controlled current flow to and from the gate to charge and discharge the gate and its parasitic capacitance, so as to increase and decrease, respectively, the output signal supplied by the output of the power transistor at a controlled rate, said drive circuit controlling said current flow by causing a voltage level that drives such current to compensate for changes in the voltage on the gate so as to make the rate at which such current flows substantially constant during said charging and discharging; and feedback circuitry that senses said output signal and substantially stops current flow to or from said control gate when it senses that said output signal has reached a desired level. - View Dependent Claims (7, 8, 9)
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10. A transceiver for driving and receiving a signal through a transformer comprising:
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a pair of input connections for receiving an input signal from a transformer coil; receiver circuitry for amplifying said input signal and producing an amplified input signal; transmitter circuitry including one or more output transistors for driving an output signal; pairs of output connections from which said output signal can be connected across said transformer coil, including a first pair for driving a center tapped transformer and a second pair for driving a bridge transformer; a center tapped transformer; and feedback circuitry for using a comparison between said amplified input signal and a desired signal level to control the amplitude of said output signal generated by said transmitter circuitry; wherein; said first pair of output connections are connected across a center tapped transformer to drive said output signal across that transformer; and said pair of input connections are connected across said center tapped transformer to receive the differential voltage across that transformer as said input signal. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A transceiver for driving and receiving a signal through a transformer, comprising:
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a pair of input connections for receiving an input signal from a transformer coil; receiver circuitry for amplifying that input signal and producing an amplified input signal; transmitter circuitry including one or more output transistors for driving an output signal; pairs of output connections for connecting said output signal across said transformer coil, including a first pair for driving a center tapped transformer and a second pair for driving a bridge transformer; feedback circuitry for using a comparison between said amplified input signal and a desired signal level to control the amplitude of said output signal; and a center tapped transformer; wherein; each output connection of said first pair of output connections has isolation circuitry for electrically isolating said output connections from said transmitter circuitry when the voltage on such a connection goes below ground; said second pair of output connections do not have such isolation circuitry; said first pair of output connections are connected across the center tapped transformer to drive said output signal across that transformer; and said pair of input connections are connected across said center tapped transformer to receive the differential voltage across that transformer as said input signal.
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17. A transceiver for both driving and receiving signals through a center tapped transformer including the transmitter, comprising:
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a pair of input connections for connection across the center tapped winding so as to receive the differential voltage across said winding; transmitter circuitry including one or more output transistors for driving an output signal; a pair of output connections from which said output signal is connected across the center tapped winding of said transformer, where each output connection of said pair has isolation circuitry for electrically isolating said output connection from the transmitter circuitry during a different portion of the output signal; feedback circuitry for using a comparison between said received differential voltage and a desired signal level to control the amplitude of said output signal; and receiver circuitry connected to said pair of input connections for producing an amplified input signal which varies as a function of said received differential voltage.
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18. A transmitter for driving an output signal through a transformer having a center tapped winding, said transmitter comprising:
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a pair of input connections for connection across the center tapped winding so as to receive the differential voltage across said winding; transmitter circuitry including one or more output transistors for driving an output signal; a pair of output connections from which said output signal can be connected across the center tapped winding of said transformer, where each output connection of said pair has isolation circuitry for electrically isolating it from the transmitter circuitry during a different portion of the output signal; and feedback circuitry for using a comparison between said received differential voltage and a desired signal level to control the amplitude of said output signal; wherein; said one or more output transistors are FET transistors each having an output contact and a control gate with a parasitic capacitance; said transmitter circuitry includes a gate drive circuit that provides a controlled current flow to and from the gate of each output transistor to charge and discharge that gate and its parasitic capacitance, so as to increase and decrease, respectively, the output signal supplied by the output contact of the output transistor, said drive circuit controlling said current flow by causing the voltage level that drives such current to compensate for changes in the voltage on the gate so as to make the rate at which such current flows more even during said charging and discharging; and said feedback circuitry substantially stops the flow of said current to or from said control gate as a function of said comparison between said received differential voltage and the desired signal level.
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19. A receiver for receiving a signal generated across a winding of a transformer, said receiver comprising:
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a pair of input connections for receiving a differential voltage input from opposite sides of said transformer winding; a separate operational amplifier associated with each of said two input connections including; two inputs, a first of which is connected to a reference voltage; at least one output connected to the second of said amplifier'"'"'s inputs to form an operational amplifier feedback loop which holds that second input at a virtual ground; a separate resistor associated with each of said two input connections, connected between said input connection and the virtual ground at the second input of the input connection'"'"'s associated amplifier, so that current in the operational amplifier feedback loop can flow through said resistor to the associated input connection to help hold the amplifier'"'"'s virtual ground at its associated reference voltage; wherein said receiver is designed to be powered by a power supply providing electrical power having a certain power supply voltage range; and whereby even if a voltage received at an input connections ranges outside the power supply voltage range, the voltage at the virtual ground input into the associated input amplifier will remain substantially constant, and, thus, within the power supply voltage range. - View Dependent Claims (20, 21, 22, 23)
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24. A transmitter for driving an output signal through a transformer, comprising:
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transmitter circuitry including one or more output transistors for driving said output signal; a pair of output connections from which said output signal is connected across said transformer coil; circuitry for producing a measurement of current flow across one or more of said output transistors; and circuitry for substantially turning off current flow in said one or more output transistor for at least a given time period when said current measurement exceeds a given level; wherein; said transmitter is powered by a power supply having two voltage rails; there are at least two complimentary pairs of said power transistors, each having two output transistors connected in series between said voltage rails with a node between them to which the pair'"'"'s associated output connection is connected; the transmitter circuitry includes circuitry for driving said two complementary pairs, so that one pair can drive current in a first direction across said transformer during one part of an output signal cycle, and the other pair can drive current in an opposite direction across said transformer during another part of the output signal cycle; each output transistor in each complementary pair has associated circuitry for producing said measurement of current flow across it; and said circuitry for substantially turning off current flow in said one or more output transistors substantially turns off current flow in all of said output transistors in response to a measurement that current flow in any one of said output transistors exceeds a given level. - View Dependent Claims (25, 27, 29)
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26. A transmitter for driving an output signal through a transformer comprising:
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transmitter circuitry including one or more output transistors for driving said output signal; a pair of output connections from which said output signal is connected across said transformer coil; circuitry for producing a measurement of current flow across one or more of said output transistors; and circuitry for substantially turning off current flow in said one or more output transistor for at least a given time period when said current measurement exceeds a given level; wherein at least a part of said transmitter is constructed as a single monolithic circuit including; said output transistors; at least part of said circuitry for measuring; at least part said circuitry for substantially turning off are all on one semiconductor chip; external connections for providing transistor drive signals to one or more external power transistors which can be used for driving an output signal across a transformer; an external current overflow connection for receiving an indication of a current overflow in one or more of said external power transistors; and circuitry for responding to such an indication of an external overflow by substantially turning off said transistor drive signals.
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28. A transmitter for driving an output signal through a transformer comprising:
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transmitter circuitry including one or more output transistors for driving said output signal; a pair of output connections from which said output signal is connected across said transformer coil; circuitry for producing a measurement of current flow across one or more of said output transistors; and circuitry for substantially turning off current flow in said one or more output transistor for at least a given time period when said current measurement exceeds a given level; wherein; said transmitter generates said output signal in response to a digital sequence of one or more successive output bits received from other circuitry; said circuitry for substantially turning off current includes latching circuitry for keeping the current turned off, once it has been turned off, until the next end of a sequence of successive output bits is received from said other circuitry; and said latching circuitry is reset after said next end of said sequence of successive output bits, so that a later sequence of successive output bits received from said other circuitry can cause said transmitter to generate another output signal.
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30. A method of operating a transceiver for driving and receiving a signal through a transformer which has two ends and a plurality of FET power transistors, each having an associated output contact for conducting current to a coil of a transformer and an associated control gate with a parasitic capacitance, said method comprising:
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connecting at each end of the transformer one of the output contacts of the FET power transistors; and providing at different times controlled current flows to and from the respective gates of the connected FET power transistors so as to charge and discharge the gates and their respective parasitic capacitances and so as to increase and decrease, respectively, the output currents supplied by the respective output contacts of the connected FET power transistors at a controlled rates, a first of the connected FET power transistors driving current across said transformer in a first direction during one part of an output signal cycle and a second of the connected FET power transistors driving current across said transformer with a second opposite direction during another part of said output signal cycle; wherein said current flows are controlled by causing voltage levels that drives such currents to compensate for changes in the voltages on the respective gates so as to make the rate at which such currents flows substantially constant during said charging and discharging. - View Dependent Claims (31, 32, 33)
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34. A method of operating an output circuit for driving a signal with a first FET power transistor and a second FET power transistor each having an output contact and a control gate with a parasitic capacitance, so a differently phased version of the signal is supplied to each output contact, said method comprising:
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providing a limited current flow to and from the respective control gates of the first FET power transistor and a second FET power transistor to charge and discharge the control gates and their respective parasitic capacitances, so as to increase and decrease, respectively, an output signal supplied by each output contact of the power transistor at a controlled rate, the first FET power transistors driving current corresponding to said signal from the output contact of said first power transistor in a first phase, and the second FET power transistors driving current corresponding to said signal from the output contact of said second power transistor in a second phase; sensing the signal on each of said output contacts; and stopping the current flow to or from each such control gate in response to the sensing of said signal. - View Dependent Claims (35, 36)
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37. A method of operating a transceiver for driving and receiving a signal through a transformer, where said transceiver includes:
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a pair of input connections for receiving an input signal from a transformer coil; receiver circuitry for amplifying that input signal and producing an amplified input signal; transmitter circuitry including one or more output transistors for driving an output signal; and pairs of output connections from which said output signal can be connected across said transformer coil, including a first pair for driving a center tapped transformer and a second pair for driving a bridge transformer; said method comprising; connecting said pair of input connections across a given transformer which is either a center trapped transformer or bridge transformer; and selecting to connect said first pair of output connections across said given transformer if it is a center tapped transformer and to connect said second pair of output connections across said transformer if it is a bridge transformer. - View Dependent Claims (38, 39, 40, 41, 42)
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43. A method of operating a transmitter for driving an output signal through a transformer having a center tapped winding, said method comprising:
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using transmitter circuitry including one or more output transistors to drive an output signal; using a pair of output connections to connect said output signal across the center tapped winding of said transformer; electrically isolating each output connection of said pair from the transmitter circuitry during a different portion of the output signal; using a pair of input connections connected across the center tapped winding to receive the differential voltage across said winding; and using a comparison between said received differential voltage and a desired signal level to control the amplitude of said output signal; wherein; said transmitter is part of a transceiver for sending and receiving signals through the center tapped transformer; and said method uses receiver circuitry connected to said pair of input connections to produce an amplified input signal which varies as a function of said received differential voltage.
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44. A method of operating a transmitter for driving an output signal through a transformer having a center tapped winding, said method comprising:
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using transmitter circuitry including one or more output transistors to drive an output signal; using a pair of output connections to connect said output signal across the center tapped winding of said transformer; electrically isolating each output connection of said pair from the transmitter circuitry during a different portion of the output signal; using a pair of input connections connected across the center tapped winding to receive the differential voltage across said winding; and using a comparison between said received differential voltage and a desired signal level to control the amplitude of said output signal; wherein; said one or more output transistors are FET transistors each having an output contact and a control gate with a parasitic capacitance; a controlled current flow to and from the gate of each output transistor is used to charge and discharge that gate and its parasitic capacitance, so as to increase and decrease, respectively, the output signal supplied by the output contact of the output transistor, said current flow being controlled by causing the voltage level that drives such current to compensate for changes in the voltage on the gate so as to make the rate at which such current flows substantially constant during said charging and discharging; and said comparison between received differential voltage and a desired signal level is used to substantially stop said current to or from said control gate as a function of said comparison.
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45. A method of operating a receiver for receiving a signal generated across a winding of a transformer, said method comprising:
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using a pair of input connections to receive a differential voltage input from opposite sides of said transformer winding; using a separate operational amplifier to receive a signal from each of said two input connections, wherein each of said operational amplifiers includes; two inputs, a first of which is connected to a reference voltage; and at least one output connected to the second of said amplifier'"'"'s inputs to form an operational amplifier feedback loop which holds that second input at a virtual ground; using a separate resistor associated with each of said two input connections, connected between said input connection and the virtual ground at the second input of the input connection'"'"'s associated amplifier, to create a signal which varies as variable amounts of current pass from the operational amplifier feedback loop to the associated input connection, so as to help hold the amplifier'"'"'s virtual ground at its associated reference voltage; wherein said receiver is powered by a power supply providing electrical power having a certain power supply voltage range; and whereby even if a voltage received at an input connection ranges outside the power supply voltage range, the voltage at the virtual ground input into the associated input amplifier will remain substantially constant, and, thus, within the power supply voltage range. - View Dependent Claims (46, 47, 48, 49)
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Specification