AD834JRZ-R7 datasheet(10/20 Pages) AD

10 / 20 page

AD834

Data Sheet

Rev. F | Page 10 of 20

EXPLANATION OF TYPICAL PERFORMANCE

CHARACTERISTICS AND TEST CIRCUITS

Figure 4 is a plot of the mean-square output vs. frequency for

the test circuit of Figure 8. 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

Figure 5).

THD data represented in Figure 6 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 ampli-

tude. Varying the ac input amplitude while maintaining a

constant dc input amplitude affects THD performance.

The squarer configuration shown in Figure 8 is used to determine

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 configuration

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

value proportional to the square of the input amplitude.

By placing the capacitors, C3/C5 and C4/C6, across the 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.

Care should be taken when laying out the board. When using

the DIP package, mount the IC socket on a ground plane with a

clear area in the rectangle formed by the pins. This is important

because significant transformer action can arise if the pins pass

through individual holes in the board; improperly constructed test

jigs have caused oscillation at 1.3 GHz.

AD834JRZ-R7 Datasheet(PDF) 10 Page - Analog Devices