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AD834AR

500 MHz Four-Quadrant Multiplier

Analog Devices 

Typical Performance Characteristics–AD834

1000

800

600

400

200

100

80

60

40

20

10

1

10

100

1000

FREQUENCY – MHz

TPC 1. Mean-Square Output

vs. Frequency

0

–10

–20

–30

–40

–50

X FEEDTHROUGH

–60

–70

–80

1

Y FEEDTHROUGH

10

100

FREQUENCY – MHz

1000

TPC 2. AC Feedthrough

vs. Frequency

0

–10

–20

–30

–40

X HARMONIC

DISTORTION

–50

–60

Y HARMONIC

–70

DISTORTION

–80

1M

10M

100M

1G

FREQUENCY – Hz

TPC 3. Total Harmonic Distortion

vs. Frequency

TPC 1 is a plot of the mean-square output versus frequency for

the test circuit of Figure 2. Note that the rising response is due

to package resonances.

For frequencies above 1 MHz, ac feedthrough is dominated by

static nonlinearities in the transfer function and the finite offset

voltages. The offset voltages cause a small fraction of the funda-

mental to appear at the output, and can be nulled out. See TPC 2.

THD data represented in TPC 3 is dominated by the second

harmonic, and is generated with 0 dBm input on the ac input

and 1 V on the dc input. For a given amplitude on the ac

input, THD is relatively insensitive to changes in the dc input

amplitude. Varying the ac input amplitude while maintaining

a constant dc input amplitude will affect THD performance.

WAVETEK 2500A

SIGNAL GENERATOR

LOW-PASS

FILTER

HP3362A

SIGNAL GENERATOR

A/B

A SWITCH B

X

W1 CH1

HP

AD834

54121A

CH2 SAMPLING

Y

W2

HEADS

DATA PRECISION 8200

VOLTAGE CALIBRATOR

HP54120A

DIGITIZING

MAINFRAME

HP330

COMPUTER

SUBTRACT

CH1–CH2

1024 POINT

FFT

Figure 1. Test Configuration for Measuring AC

Feedthrough and Total Harmonic Distortion

The squarer configuration shown in Figure 2 is used to deter-

mine wideband performance because it eliminates the need for

(and the response uncertainties of) a wideband measurement

device at the output. The wideband output of a squarer configu-

ration is a fluctuating current at twice the input frequency with a

mean value proportional to the square of the input amplitude.

By placing capacitors C3/C5 and C4/C6 across load resistors R1

and R2, a simple low-pass filter is formed, and the mean-square

value is extracted. The mean-square response can be measured

using a DVM connected across R1 and R2.

SMA FROM

HP8656A

SIGNAL

GENERATOR

SMA TO

HP436A

POWER

METER

L1

1␮H

8765

X2 X1 +VS W1

AD834

Y1 Y2 –VS W2

1234

R4

75⍀

C1

0.1␮F

+5V

C3

C5

560pF 0.1␮F

C4

C6

560pF 0.1␮F

R1

49.9⍀

TO

HP3456A

DVM

R2

49.9⍀

C2

R3

0.1␮F

10⍀

–5V

DENOTES A SHORT DIRECT CONNECTION TO THE GROUND PLANE

Figure 2. Bandwidth Test Circuit

+15V

+5V

0.1␮F

0.1␮F

X

IW1

8765

X2 X1 +VS W1

AD834

Y1 Y2 –VS W2

1234

Y

0.1␮F

IW2

–5V

AD707

A1

0.1␮F

–15V

1k⍀

+15V

0.1␮F

AD707

A2

0.1␮F

NOTES

R1, R2 SHOULD BE PRECISION TYPE

–15V

RESISTOR (؎0.1%).

ABSOLUTE VALUE ERRORS OF R1, R2 WILL

1k⍀

CAUSE A SCALE FACTOR ERROR.

R1, R2 MISMATCHES WILL BE EXPRESSED

AS LINEARITY ERRORS.

VOUT = IW1 R1 – UW2 R2

(IF R1 = R2, VOUT = >IW R1).

1k⍀

+

VOUT

1k⍀

–

Figure 3. Low-Frequency Test Circuit

REV. D

–5–

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