Gamry Reference 3000 - Bandwidth Selection; Aux A;D Specifications; Function Call to Set the Aux A;D BNC Characteristics

Appendix D -- Auxiliary A/D Input Characteristics--Bandwidth Selection
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Bandwidth Selection
J900 (or on some boards J901) controls the bandwidth of the Aux A/D input. With J900 (or J901) removed,
there is no filtering on this input and the –3 dB bandwidth is greater than 300 kHz.
With J900 (or J901) in place (the default setting), a single pole RC filter is used to limit noise into the A/D. The
nominal cutoff frequency of this filter is 20 Hz.
Note that source impedances greater than 1 kΩ will appreciably lower this cutoff frequency. When the Aux
A/D input is driven by a source with an output impedance of 1 MΩ, the frequency cutoff will be less than 0.25
Hz.
The CMOS switch performs the same function as the jumper.
Aux A/D Specifications
Range
±3.276 volts
Input Impedance
100 kΩ (approx)
Low Impedance Selected
or
10 GΩ (typical)
High Impedance Selected
Input Bias Current < 10 nA High Impedance selected
Filter Cutoff
20 Hz ± 20%
With Low Bandwidth selected
Function Call to Set the Aux A/D BNC Characteristics
The CMOS switch is set using an Explain function call. The syntax of this call is:
Pstat.SetAuxBNCSettings (Impedance, Bandwidth)
Both variables passed to the function are Booleans (with a value of TRUE or FALSE).
The following definitions can be used to make a script that calls this function more readable.
#define SETAUXBNCSETTINGS_IMPEDANCE_HIGH TRUE
#define SETAUXBNCSETTINGS_IMPEDANCE_LOW FALSE
#define SETAUXBNCSETTINGS_BANDWIDTH_HIGH TRUE
#define SETAUXBNCSETTINGS_BANDWIDTH_LOW FALSE
A TRUE in the Impedance variable opens the switches across J902 and J903, selecting high input impedance. A
FALSE selects 100 k input impedance.
A TRUE in the Bandwidth variable opens the switch across J901, selecting high bandwidth. A FALSE selects low
pass filter at nominally 20 Hz.