US 11,853,089 B2
Expanded shunt current source
Wayne C. Goeke, Hudson, OH (US)
Assigned to Keithley Instruments, LLC, Solon, OH (US)
Filed by Keithley Instruments, LLC, Solon, OH (US)
Filed on Jul. 23, 2020, as Appl. No. 16/937,338.
Claims priority of provisional application 62/878,613, filed on Jul. 25, 2019.
Prior Publication US 2021/0026386 A1, Jan. 28, 2021
Int. Cl. G05F 1/575 (2006.01); G01R 1/20 (2006.01)
CPC G05F 1/575 (2013.01) [G01R 1/20 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A current source, comprising:
at least one gain component having a constant gain at frequencies below a frequency point, and having a gain inversely proportional to frequency at frequencies above the frequency point, the gain component having a first input, a second input, and an output;
a source resistor connected in series with the output of the gain component and connected to a high terminal of a current source output, the gain component configured to regulate a voltage across the source resistor to be a source voltage, the gain of the gain component limiting regulation by the gain component of the source voltage and an output voltage across a load between the high terminal and a low terminal of the current source output;
an inductance in series with the source resistor, the inductance sized to have an impedance equal to the resistance of the source resistor at the frequency point to extend a range of frequencies over which the current source holds a resistance; and
a feedback component connected to the low terminal and an input of the gain component, the feedback component to receive at least a portion of the output voltage the feedback component configured to reduce the gain of the gain component available to regulate the source voltage across the source resistor to make the source resistor appear larger than a load resistance between the high and low terminals.