User`s guide

Agilent E6432A Microwave Synthesizer User’s Guide 2-11

Hardware Front Panel Connectors

FM Input

FM Input, available from the Hardware Front Panel on standard

instruments and instruments with Option 002, is used to supply

frequency modulation input signals from external signal sources such

as arbitrary waveform generators and function generators.

A frequency modulation signal can be applied by itself or at the same

time as an amplitude modulation or pulse modulation signal.

Standard instruments

This input accepts a –10 Vp to +10 Vp signal with 1 MHz/V sensitivity.

Any signal greater than these limits causes distortion. The deviation

changes linearly as the FM input changes from 0 to its upper and lower

voltage limit. The input impedance for this input connector is

2 kilohms. Damage levels for this input are greater than or equal to

+15 Vp, or less than or equal to –15 Vp.

Instruments with Option 002

Adding Option 002 adds low rate FM capability. This option is not

available on instruments with I/Q modulation (Option UNG).

Instruments with Option 002 accept a –10 Vp to +10 Vp signal with

100 kHz/V, 1 MHz/V, 10 MHz/V sensitivities. Any signal greater than

these limits causes distortion. The deviation changes linearly as the

FM input changes from 0 to its upper and lower voltage limit.

The input impedance for this input connector is 2 kilohms. Damage

levels for this input are greater than or equal to +15 Vp, or less than or

equal to –15 Vp.

For complete specifications, refer to “Specifications and

Characteristics” on page 6-1.

TIP When using a signal generator to drive the FM input, the output

impedance of the signal generator must be taken into account. If the

signal generator has an output impedance of 50 ohms and it is set to

output a –1 Vp to +1 Vp signal into a 50-ohm load, the actual signal

level at the FM input will be a –2 Vp to +2 Vp. This occurs because the

FM input on the synthesizer has a 2 kilohm input impedance; a –2 Vp

to +2 Vp signal at the FM input will generate a 4 MHz FM peak-to-peak

modulation.

One solution to remedy this impedance mismatch is to place a BNC tee

connector on the FM input with a 50-ohm load connected to one port of

the BNC tee connector. The input signal from the signal generator

would be connected to the other port so that the output impedance of

the signal generator sees approximately a 50-ohm input impedance as a