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Analog To Digital Converter, Transformer Input

IP.com Disclosure Number: IPCOM000096165D
Original Publication Date: 1963-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Walton, CA: AUTHOR

Abstract

This analog to digital converter uses a transformer input to provide common mode rejection. The unknown voltage to be measured is applied to terminals 1. To initiate a conversion, switches 2 and 3 are closed which induces a voltage across secondary winding 4 of transformer 5. This voltage is applied to the input of amplifier 6. Here it is increased in amplitude and then fed to level detector 7. The output of level detector 7 appears on line 8 indicating a positive polarity for the voltage across winding or on line 9 to indicate a negative polarity for this voltage.

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Analog To Digital Converter, Transformer Input

This analog to digital converter uses a transformer input to provide common mode rejection. The unknown voltage to be measured is applied to terminals 1. To initiate a conversion, switches 2 and 3 are closed which induces a voltage across secondary winding 4 of transformer 5. This voltage is applied to the input of amplifier 6. Here it is increased in amplitude and then fed to level detector 7. The output of level detector 7 appears on line 8 indicating a positive polarity for the voltage across winding or on line 9 to indicate a negative polarity for this voltage.

Depending on a signal over lines 8 or 9, control logic 10 operates to generate a feedback voltage by means of digital to analog converter 11.

The analog feedback voltage from digital to analog converter 11 travels on lines 13 and 14 to winding 15 on transformer 16. The voltage induced across winding 17 as a result of the feedback voltage appears in series with the unknown voltage at terminals 1 and winding 18 of transformer 5. Winding 18 is, therefore, energized with the difference between the feedback voltage and the unknown voltage.

The control logic modifies the output of the digital to analog converter 11. This occurs until the voltage across winding 4, representing the difference between the digital reference and the unknown voltage, is zero. This modification can be of the successive approximation method as shown or a ramp type generator.

Since the w...