# FM modulation using Agilent 33220A Arbitrary Waveform Generator

Question asked by hidir on Feb 14, 2013
Latest reply on Feb 23, 2013 by hidir
Hi,
I need to have an FM input signal for my circuit. The 33220A signal generator is capable of generating an internal FM signal with maximum 20KHzmodulating signal. So i am using two 33220A signal generators one's output is connected to another's Modulation In connector in the back. In the user manual (http://cp.literature.agilent.com/litweb/pdf/33220-90002.pdf) page 85
it is written that :
"If you select the External source, the carrier waveform is modulated
with an external waveform. The frequency deviation is controlled by
the ±5V signal level present on the rear-panel Modulation In
connector. For example, if you have set the deviation to 100 kHz,
then a +5V signal level corresponds to a 100 kHz increase in frequency.
Lower external signal levels produce less deviation and negative
signal levels reduce the frequency below the carrier frequency.".

For an FM signal assuming frequency deviation Df=kf * Am where kf is sensitivity Hz/V and Am is the modulating signal amplitude; does it mean that for an FM signal with Df=100KHz i need to give Am=10Vpk-pk= 5V in amplitude? Does kf=20KHz/V ? If i apply Df=100KHz from the first signal generator (in which i set carrier frequency and external FM option) and Am=2Vpk-pk=1V in amplitude sine wave from the signal generator will i end up with Df=20KHz ?

Thanks