Keysight 33210A Guide D'utilisation page 349

Square Waveform Generation
To eliminate distortion due to aliasing at higher frequencies, the 33210A uses a
different waveform generation technique to create square waves. Square
waveforms are created by routing a DDS-generated sine wave into a comparator.
The digital output from the comparator is then used as the basis for the square
wave output. The duty cycle of the waveform can be varied by changing the
comparator's threshold.
Waveform
Square Waveform Generation Circuitry
Keysight 33210A User's Guide
Anti-Aliasing
DAC
Threshold
Voltage DAC
Filter
Comparator
Tutorial 7
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