NI PXI-5411/5431
Analog Output

Analog waveforms generate as follows:

1. The 12-bit digital waveform data is passed 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   You can fine tune the DAC output for gain and offset. Because the offset is adjusted before the main attenuators and amplifier, it is referred to as pre-attenuation offset. Separate DACs perform the fine tuning of gain and offset.

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 front panel connector.

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

The following figure shows the timing relationships of the trigger input, waveform output, and marker output. t_d1 is the pulse width on the trigger signal. t_d2 is the time delay from trigger to output on ARB output. t_d3 is the time between the marker output and ARB output. t_d4 is the pulse width on marker output.

Note  You can switch off the analog lowpass filter at any time during waveform generation. When you change this setting, the bouncing of electromechanical relays on the NI PXI-5411/5431 distorts the output signal for about 10 ms.