Pstat.SetIchFilter()

Type: INSTANCE FUNCTION

Purpose: Pstat.SetIchFilter() sets the filter on the current-measuring channel.

This is a different filter than the I/E Filter described in the SetStability() section. It has no effect on potentiostat stability, only on the current-measuring circuit's frequency response.

The filter is a two-pole low-pass Butterworth filter.

The filter frequency can be set in one of four ways. The type of argument passed to this function determines how it is set.

If the argument passed to the function is a REAL, it is interpreted as a frequency. The filter is set so that frequency passes through the filter with less than 3 dB of attenuation.
If the argument is an INDEX, the filter is set as described in the table below.
If the argument is a string constant that translates to an INDEX, that Index is used to set the frequency. For example, the string constant “PC5_FilterSlow” is defined to have the value 3, which the table below lists as a 5 Hz filter.
There is a special case when the argument is a BOOLEAN FALSE. Note the string constant “PC5_FilterGnd” translates to the Boolean value FALSE. The filter is set to 0.0 Hz, so it becomes a No Pass filter. This setting is only used in calibration.

NOTE: Do not use the No Filter setting (0) under normal circumstances. It is to be used exclusively for AC impedance measurements beyond 100 kHz.

NOTE: The index and strings used to set the filter cutoff frequency are different depending on the instrument Family. The Reference Family of instruments has five filter setting (including No Pass). The Interface family has six filter settings.

Usage: FilterSet = Pstat.SetIchFilter(Freq)

Freq

The function argument Freq can be a REAL frequency. The filter is set so that frequency passes through the filter with less than 3 dB of attenuation.

Alternatively, Freq can be an INDEX, BOOLEAN, or a string constant that translates into an INDEX or BOOLEAN. See the tables below.

Reference Family Filter Settings

String Constant	Value	–3 dB Frequency
PC5_FilterOff	0	No filter. Passes maximum EIS frequency.
PC5_FilterFast	1	200 kHz filter
PC5_FilterNorm	2	1 kHz filter
PC5_FilterSlow	3	5 Hz filter
PC5_FilterGnd	FALSE	0.0 Hz. Filter output is a DC 0.0 V.

Interface Family Filter Settings

String	Constant Value	–3 dB Frequency
PC5_FilterOff	0	No filter. Passes maximum EIS frequency.
PC5_FilterFast	1	200 kHz filter
PC5_FilterMedFast	2	10 kHz filter
PC5_FilterNorm	2	1 kHz filter
PC5_FilterSlow	3	5 Hz filter
PC5_FilterGnd	FALSE	0.0 Hz. Filter output is a DC 0.0 V.

FilterSet

The return value FilterSet is an INDEX or a BOOLEAN. The tables above describe the return value. Note that the function does not return the REAL or string constant if one was used as the function’s argument.