Keysight 81150A - Output Amplitude Control

Tutorial
81150A and 81160A User’s Guide 631
7.9 Output Amplitude Control
Introduction
The Keysight 81150A and 81160A uses a variable reference voltage to
control the signal amplitude over a 1dB range. As shown in the simplified
block diagram below, the output of the waveform DAC goes through an anti-
aliasing filter. An adjustable alternator (0dB to 62dB) is used to control the
output amplitude in 1dB steps over a wide range of amplitude values
(10 mVpp to 10 Vpp).
Main
Output
Waveform
DAC
Anti-Aliasing
Filter
DC Offset
DAC
0 to 60 dB
in 1 dB Steps
Attenuator
+
High Bandwidth
Amplifier
Low Bandwidth
Amplifier
Switching
Circuitry
Variable
V
ref
Output Amplitude Control of 81150A
The 81160A has one amplifier.
DC Offset
The dc offset is summed with the ac signal in the output amplifier. This
allows relatively small ac signals to be offset by relatively large dc voltages.
For example, you can offset a 100 mVpp signal by almost 5 Vdc (into a 50
load).