NI PXI/PCI-5401
Analog Output

Analog waveforms generate as follows:

1. The 12-bit digital waveform data is fed to a high-speed DAC.
2. A lowpass filter filters the DAC output.
3. This filtered signal is amplified before it goes to a 10 dB attenuator.

   Note  The DAC output can be fine-tuned for gain and offset. Since the offset is adjusted before the main attenuators and amplifier, the offset is referred to as pre-attenuation offset. The fine-tuning of gain and offset is performed by separate DACs.

4. The output from the 10 dB attenuator then goes to the main amplifier, which can provide up to ±5 V levels into 50 Ω. An output relay can switch between ground level and the main amplifier.
5. The output of this relay goes to a series of passive attenuators.
6. The output of the attenuators goes through a selectable output impedance of 50 Ω or 75 Ω to the I/O connector.

The following figure shows the essential block diagram of analog waveform generation.

The following figure shows the timing relationships of the trigger input and waveform output. t_d1 is the pulse width on the trigger signal. t_d2 is the time delay from trigger to output on ARB output.