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Analog-to-Digital Converter DC Restore with 5.0-Volt Supply

IP.com Disclosure Number: IPCOM000102264D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Gamble, C: AUTHOR

Abstract

Traditionally driving analog-to-digital converters (ADCs) was accomplished by using an external, relatively high powered operational amplifier with plus and minus 12-volt supplies. The task is quite easily accomplished. (Image Omitted)

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This is the abbreviated version, containing approximately 52% of the total text.

Analog-to-Digital Converter DC Restore with 5.0-Volt Supply

       Traditionally driving analog-to-digital converters (ADCs)
was accomplished by using an external, relatively high powered
operational amplifier with plus and minus 12-volt supplies.  The task
is quite easily accomplished.

                            (Image Omitted)

      A requirement for this particular application was to drive an
ADC with a single 5 VDC supply and the ADC driver fully integrated in
the ADC, which help to minimize the total power consumption.
Additionally, the driver must have a small signal bandwidth of 200
MHz and the maximum output voltage swing of 1.75 V peak-to-peak with
a DC bias point of about 3.1 V.  The ADC driver amplifier is designed
to drive the 64 comparators of the analog-to-digital converter and to
steer the DC bias voltage of the output analog signal.  The input
voltage to the ADC driver circuit is AC coupled to the small signal
source, and the maximum allowable AC peak-to-peak amplitude is about
0.437 V peak- to-peak.  The ADC driver op-amp is configured to have
an AC gain of two.  The analog-to-digital converter requires two
reference voltages.  The reference voltages may be supplied with a
simple resistor voltage ladder and appropriate buffering.  The
reference voltages track the power supply.  As a result of ADC design
constraints, the lower reference voltage had a minimum voltage
requirement of 2.1 VDC.  The upper voltage reference was constrained...