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Auxiliary I/O Connector: Analog IN/OUT

Question asked by JrV on Jan 18, 2011
Latest reply on Jan 19, 2011 by Dr_joel
Hello,

I like to use the Auxiliary I/O Connector (N5230C PNA-L) to read/write external components for DC power measurements and control.

For the Analog Out 1, 2 (pins 2, 3) I read
Description:
- Two analog outputs programmable to +/-10V; Iout<10mA; Rout=100 ohms
- 12-bit DACs with voltage resolution of approximately 5mV/count. The DACs are set to constant values using SCPI or COM, and can be read using SCPI or COM commands.
- Preset state for both pins is 0 volts.
HW Details:
-Looking into this output pin is a 100-ohm series resistor followed by two diodes tied to +/-15V for static protection, then the output or an op-amp.
- The voltage output is provided by a 12-bit DAC with an op amp buffer.
Specifics:
- Maximum output current = 10mA
- Settling time  = 3us
Timing:
- The DACs are set after the last data point is measured, during  retrace. If the analyzer is in single sweep mode, the DACs are set as part of the presweep process, before the sweep is triggered.


For the Analog In (pin 14) I read:
- Beginning with PNA Rev. A.07.21, voltages on this pin can be read using ADC receiver measurements.
Description:
- Analog input, +/-10V range, Rin=100k ohm
- Bandwidth = 40kHz (2-pole lowpass filter).
- This analog input may be read using the SCPI or COM commands.
HW Details:
- Looking into this pin there is 1k-ohm series resistor followed by 100k-ohm resistor to ground, static protection diodes after the 1k resistor limit the signal to +/-15V,  then a high impedance buffer and active filter limiting the bandwidth to 40kHz with a lowpass filter.



On the PCB I place a buffer at the end of the Analog Out, this buffer (op-amp base unity gain buffer) has an input impedance = infinite.
My question: do I need, in some way, to source or sink the current Iout.
Are there other issues that I need to take into account?

Same for Analog In, here I place also first a buffer (op-amp base unity gain buffer) before I enter the analog pin with a signal.
Are there here issues that I need to take into account.

Regards,
JrV  

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