Optical isolation amplifier with sigma-delta modulation
First Claim
1. An optical isolation amplifier package comprising:
- an input chip having a chopper-stabilized sigma-delta converter for converting an analog input signal to a digital signal;
a light source for optically transmitting the digital signal; and
an output chip having;
means for detecting the optically transmitted digital signal; and
means for converting the optically transmitted digital signal into an analog output signal substantially proportional to the analog input signal.
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Abstract
The present invention provides an optical isolation amplifier which generates a low-noise analog output signal linearly related to an analog input signal and which conveniently fits within a conventional 8-pin dual in-line package. The optical isolation amplifier package includes an input chip having a sigma-delta analog-to-digital (A/D) converter for converting an analog input signal to a digital signal. The sigma-delta converter is used to modulate an off-chip LED which optically transmits the signal to a photodetector on a separate output chip having an accurate optical recovery section for reproducing the transmitted signal. Also contained on the output chip is a digital-to-analog (D/A) converter for converting the digital signal to an analog output signal linearly related to the analog input signal.
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Citations
23 Claims
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1. An optical isolation amplifier package comprising:
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an input chip having a chopper-stabilized sigma-delta converter for converting an analog input signal to a digital signal; a light source for optically transmitting the digital signal; and an output chip having; means for detecting the optically transmitted digital signal; and means for converting the optically transmitted digital signal into an analog output signal substantially proportional to the analog input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An optical isolation amplifier comprising:
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input pads for receiving an analog input signal; a sigma-delta converter coupled to the input pads for converting the analog input signal to a digital pulse stream; an encoder coupled to the sigma-delta converter for converting the digital pulse stream to edge-encoded digital signals; and an optical transmitter/receiver coupled to the encoder for transmitting an optical signal indicative of the digital signal over an optical channel and detecting the transmitted optical signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for sensing signals in a system comprising the steps of:
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providing an optical isolation amplifier having an input chip including a sigma-delta analog-to-digital converter optically coupled to an output chip; passing an analog voltage input signal into the isolation amplifier; converting the analog voltage signal to a plurality of digital pulses having a time-average value substantially equal to the analog voltage input signal; edge-encoding the digital pulses; and modulating a light emitting diode with the edge-encoded digital pulses. - View Dependent Claims (20, 21)
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22. An optical isolation amplifier package comprising:
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an input chip having a p-channel punch-through device coupled to a sigma-delta converter for receiving an analog signal and converting the analog signal to a digital signal; a light source for optically transmitting the digital signal; and an output chip optically coupled to the light source for receiving the digital signal. - View Dependent Claims (23)
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Specification