NI 5412
Analog Output

The following figure shows the NI 5412 Analog Output signal path.

Legend

NI 5412 Analog waveforms are generated as follows:

1. The 14-bit digital waveform data from the Waveform Generation Engine is passed to a to a digital gain circuit then a high-speed DAC. This DAC also implements a portion of the Analog Output signal path attenuation with a range of 0 dB to 3 dB. Refer to the module specifications for the exact resolution. You can adjust the amount of attenuation by configuring the Arbitrary Waveform Gain or Amplitude properties, or the NIFGEN_ATTR_ARB_GAIN or NIFGEN_ATTR_FUNC_AMPLITUDE attributes. NI-FGEN calculates and sets the correct amount of attenuation required, corresponding to the gain setting.
2. Following the DAC are the High-Gain and Low-Gain amplifiers. NI-FGEN selects the High-Gain or Low-Gain Amplifier paths by default. To select the path manually, refer to the Analog Path property or NIFGEN_ATTR_ANALOG_PATH attribute.
3. The signal then passes through attenuators, and amplifiers.
4. The signal then passes through the DC Offset Amplifier that adds the desired DC offset voltage. You can adjust the amount of DC offset added to the signal, up to one half the value of the NI-FGEN gain setting. For more information, refer to the Arbitrary Waveform Offset and DC Offset properties, or the NIFGEN_ATTR_ARB_OFFSET and NIFGEN_ATTR_FUNC_DC_OFFSET attributes.
5. The signal then passes through the Pre-Amp Attenuation section, a set of selectable solid-state attenuators that provide 0 dB to 12 dB of attenuation in 3 dB increments. You can adjust the amount of attenuation by adjusting NIFGEN_ATTR_ARB_GAIN. NI-FGEN calculates and sets the correct amount of attenuation required, corresponding to the gain setting. Refer to the Arbitrary Waveform Gain and Amplitude properties, or the NIFGEN_ATTR_ARB_GAIN and NIFGEN_ATTR_FUNC_AMPLITUDE attributes for more information.
6. Following the Pre-Amp Attenuation section, the signal can take one of two paths: the High-Gain or Low-Gain Amplifier path. NI-FGEN automatically selects the best amplifier path between the High-Gain and Low-Gain amplifiers by default based on the gain or amplitude setting. Alternatively, you can set the signal path to remain constant regardless of the gain setting for applications requiring one path or the other. Refer to the Analog Path property or the NIFGEN_ATTR_ANALOG_PATH attribute for more information.
   1. The High-Gain Amplifier path is used for waveform output voltages greater than ±1.0 V into 50 Ω. The amplifier has a fixed gain and is included in the signal path to enable the AWG to provide the maximum V_pk-pk.
   2. The Low-Gain Amplifier path is used for waveforms that have all output voltages equal to or smaller than ±1.0 V into 50 Ω. The amplifier has a fixed gain.
7. The signal passes through the Post Amp Attenuation section, a set of two passive attenuators 12 dB and 24 dB. You can adjust the amount of attenuation by configuring the Arbitrary Waveform Gain and Amplitude properties, or the NIFGEN_ATTR_ARB_GAIN and NIFGEN_ATTR_FUNC_AMPLITUDE attributes. NI-FGEN calculates and sets the correct amount of attenuation required, corresponding to the gain setting.
8. The signal then passes through the Output Enable relay. When the Output Enable relay is disabled, ground is connected to the output through a 50 Ω or a 75 Ω resistor. Intentionally, waveform generation continues while the output enable relay is disabled. When the relay is enabled, the analog waveform is seen at the CH 0 connector. You can enable or disable the output of the analog waveform generator, refer to the niFgen Output Enable VI or the niFgen_ConfigureOutputEnabled function for more information.
9. The signal then passes through a 50 Ω/75 Ω selector to the CH 0 connector. You can configure the output impedance of the analog waveform generator, refer to niFgen Configure Output Impedance VI or the niFgen_ConfigureOutputImpedance function.

Note  The NI 5412 uses mechanical relays to switch between the optional paths and sections in the Analog Out path. When you change a setting that results in a relay to switch, the bouncing of electromechanical relays on the NI 5412 distorts the output signal for about 10 ms.