Capacitance coupled isolation amplifier and method
First Claim
1. An isolation amplifier for producing an isolated output signal in response to a differential input signal, said isolation amplifier comprising in combination:
- a. first means for producing first and second signals each having a triangular wave shape, said first and second signals being substantially complementary;
b. floating power supply means for producing an electrically floating D C voltage difference;
c. first and second coupling means for capacitively coupling first portions of said first and second signals, respectively, to said floating power supply means; and
d. input circuit means receiving operating power from said floating power supply means for receiving and operating upon said differential input voltage, said input circuit means being electrically floating.
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Accused Products
Abstract
An isolation amplifier includes an electrically floating comparator having inputs coupled to inputs of the isolation amplifier. Operating power is supplied to the isolation amplifier by an electrically floating rectifier circuit. A triangular waveform generator produces a triangular output signal which is combined by means of a first coupling capacitor with a differential input signal applied to the inputs of the isolation amplifier. A second coupling capacitor couples the triangular waveform to the floating rectifier circuit. The floating comparator circuit produces a pulse width modulated output signal representative of the magnitude of the differential input signal. A demodulator circuit inverts the pulse width modulated signal to an analog output signal which is an amplified replica of the differential input signal. The analog output signal is electrically isolated from the differential input signal.
83 Citations
16 Claims
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1. An isolation amplifier for producing an isolated output signal in response to a differential input signal, said isolation amplifier comprising in combination:
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a. first means for producing first and second signals each having a triangular wave shape, said first and second signals being substantially complementary; b. floating power supply means for producing an electrically floating D C voltage difference; c. first and second coupling means for capacitively coupling first portions of said first and second signals, respectively, to said floating power supply means; and d. input circuit means receiving operating power from said floating power supply means for receiving and operating upon said differential input voltage, said input circuit means being electrically floating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating isolation amplifier circuitry to produce an isolated output signal, the isolation amplifier circuitry including electrically floating circuitry for receiving and operating upon the differential input voltage, said method comprising the steps of:
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a. producing a first signal having a triangular wave shape; b. capacitively coupling a first portion of said first signal to an electrically floating power supply circuit; c. producing an electrically floating D C voltage difference by means of the electrically floating power supply; and d. applying said electrically floating D C voltage difference to the electrically floating circuitry. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method of operating amplifier circuitry to amplify a differential input signal applied to first and second inputs of the amplifier circuitry to produce an output signal which is isolated from the differential input signal, the first input having a floating ground voltage level thereon, the amplifier circuitry including
i. comparator circuitry having first and second inputs coupled, respectively, to the first and second inputs of the amplifier circuitry and also having first and second outputs, the comparator circuitry being electrically floating, ii. power supply circuitry for supplying electrical power to the comparator circuitry, the power supply circuitry also being electrically floating, and iii. demodulator circuitry coupled to the first and second outputs of the comparator circuitry to demodulate a pulse width modulated output produced at the first and second outputs of the comparator circuitry, the demodulator circuitry having an output at which the output signal of the amplifier circuitry is produced, said method comprising the steps of: -
a. producing a triangular waveform signal; b. capacitively coupling a portion of said triangular waveform signal to the power supply circuitry to provide operating power for the power supply circuitry; c. capacitively coupling a portion of said triangular waveform signal to a first conductor, the first conductor being electrically coupled to one of the first and second input nodes of the amplifier circuitry, hereby superimposing the portion of the triangular waveform signal capacitively coupled to the first conductor onto the differential input voltage; d. producing a pulse width modulated output signal between the first and second outputs of the comparator circuitry in response to said superimposing, said pulse width modulated output signal representing the magnitude of the differential input signal; and e. demodulating the pulse width modulated output signal to produce the output signal of the amplifier circuitry, the output signal of the amplifier circuitry being an amplified version of the differential output signal and being isolated from the differential input signal.
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Specification