This module is designed as a versatile source for V-I or I-V measurements.
The [Source mode] switch sets the module operating as:
[V] a voltage source with the [RANGE] switch setting the current limit to approx 3x(1nA..20mA)
[V+R] a voltage source with [RANGE] setting the output resistance (1Gohm..50ohm)
[I] a current source with [RANGE] setting the current range (1nA..20m A/V)
Optionally an additional logarithmic range setting can be implemented creating a single range
full 100pA to 10mA span (but less accurate).
Using the buffered monitor outputs [mon out] it can even be used as a source-measure-unit (Vsource/Imeas or Isource/Vmeas). Bandwidth of these monitor signals is >10kHz.
The [R-out] switch makes it possible to set the output resistance of the selected [V] or [I] source (R is set by 1/[RANGE]). The R/1000 1000R, being the usual setting, gives the highest accuracy. The R/10 10R gives the lowest noise.
The output [symm/single] switch selects two output modes:
-single: pin 4 is the output node delivering the selected current/voltage, pin 2 is connected to ground (classic current/voltage source). The LED [V-out] shows the output voltage
-symmetric: pin 4 is the output node delivering the selected current/voltage, pin 2 is a node at exactly the opposite voltage level of pin 4 driven from a source-resistance 1/R set by [RANGE].
The output voltage is then symmetrical to ground (if the sample is not grounded).The LED [V-unbal] lights up if there is an error causing unbalance in the output voltage. Applications of symmetric operation are: preventing a common mode voltage across the sample, preventing a common mode voltage on the voltage amplifier, doubling the maximum voltage output swing of the current/voltage source. Selecting the symmetric mode gives 4..8V maximum output voltage.
The symmetric mode has a slightly higher noise level.
The unit has 2 control inputs: x1 and x0.01, these can be used to have a dc-sweep (x1 input using a dac) with a modulation (lock-in on x0.01 via the iso-amp input).
The routing should be set in the summing module S2.
Example:When S4c placed in slot C, inputs are CV1 and CV2.
Default ONLY the x1 input is enabled in the module. The x0.01 input can be enabled/disabled by a jumper inside. The input signals are summed inside the module.
PCboard: the white jumper is set to "E" which enables x001:
When the output voltage exceeds 2..4 Volt (depends on loadresistance) an overload LED indicates [clip] The sample resistance is then too high for the given current or too low for the given voltage.
lemo [OUT] pin 4/2/3 connection:
single: 4=out / 2=ground / 3=ground
symm: 4=out / 2=-out / 3=ground
for IVVI-rack only: Enabling x0.01 means that only ONE source can be used in the rack. (both Iso-amps are used then to provide the x1 and x0.01 signal)