SMP04ES View Datasheet(PDF) - Analog Devices

Part Name

Description

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SMP04ES

CMOS Quad Sample-and-Hold Amplifier

Analog Devices 

SMP04

0

0

V1

V2 VIN (0V TO 8V)

S/H

S/H (DELAYED)

+12V

VDD

VSS

VSS

INSTRUMENTATION AMP

+12V

V1

RG

AMP02

V2

VOUT = G(V1–V2)

G=

50k⍀

RG

+1

td

t1 t2

1/2 SMP04

VSS

–5V OR –12V

DGND

Figure 23. Time Delta Sample-and-Difference Measurement

SAMPLE AND DIFFERENCE AMPLIFIER (Figure 23)

This circuit uses two sample-and-holds to measure the voltage

difference of a signal between two time points, t1 and t2. The

sampled voltages are fed into the differential inputs of the AMP02

instrumentation amplifier. A single resistor RG sets the gain of

this instrumentation amplifier. Using two channels of the

SMP04 in this application has the advantage of matched

sample-and-hold performance, since they are both on the same

chip.

SINGLE SUPPLY, SAMPLING, INSTRUMENTATION

AMPLIFIER (Figure 24)

This application again uses two channels of the SMP04 and an

instrumentation amplifier to provide a sampled difference signal.

The sample-and-hold signals in this circuit are tied together to

sample at the same point in time. The other two parts of the

SMP04 are used as amplifiers by grounding their control lines

so they are always sampling. One section is used to drive a

guard to the common-mode voltage and the other to generate a

+6 V reference to serve as an offset for single supply operation.

+ INPUT

S/H

– INPUT

GUARD

GUARD

GUARD

DRIVE

1/4

SMP04

1/4

SMP04

+12V

1/4

SMP04

+12V

20k⍀

20k⍀

50k⍀

50k⍀

+12V

GAIN =

50k⍀

RG

+1

0.1␮F

RG AMP02

REFERENCE

VOUT

0.01␮F

1/4

SMP04

+6V REFERENCE

Figure 24. +12 V Single Supply Sampling Instrumentation Amplifier with Guard Drive

–12–

REV. D

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