252 Keysight E8357D/67D & E8663D PSG User’s Guide
Multitone Waveform Generator
Overview
Overview
The multitone mode builds a waveform that has up to 64 CW signals, or tones.
Using the
Multitone Setup
table editor, you can define, modify, and store
waveforms for playback. Multitone waveforms are generated by the internal
I/Q baseband generator.
The multitone waveform generator is typically used for testing the
intermodulation distortion characteristics of multi–channel devices, such as
mixers or amplifiers. Intermodulation distortion (IMD) occurs when non–linear
devices with multiple input frequencies cause unwanted outputs at other
frequencies or interfere with adjacent channels. The multitone waveform
generator supplies a waveform with a user–specified number of tones whose
IMD products can be measured using a spectrum analyzer and used as a
reference when measuring the IMD generated by a device–under–test.
Multitone waveforms are created using the internal I/Q baseband generator
and stored in ARB memory for playback. Although the multitone mode
generates a high–quality waveform, a small amount of IMD, carrier
feedthrough, and feedthrough–related IMD occurs. Carrier feedthrough may
be observed when an even number of tones are generated, since there are no
tones at the center carrier frequency to mask the feedthrough. To minimize
carrier feedthrough for an even–numbered multitone signal, it is necessary to
manually adjust the I and Q offsets while observing the center carrier
frequency with a spectrum analyzer.
For measurements that require more than 64 tones or the absence of IMD and
carrier feedthrough, you can create up to 1024 distortion–free multitone
signals using Keysight Technologies Signal Studio software Option 408.
NOTE
For more information about multitone waveform characteristics and the PSG
vector signal generator multitone format, download
Application Note 1410
from our website by going to
http://www.keysight.com
and searching for “AN
1410” in Test & Measurement.
