Electrical impedance spectroscopy
A device may perform impedance spectroscopy on a component under test. The frequency response analyzer circuitry may be coupled to the component under test outside of a current loop supplying an operational current to the component under test. The frequency response analyzer circuitry may drive a variable impedance circuit to generate an oscillating current component within the current loop. The frequency response analyzer circuitry may monitor a frequency response of the component under test to the oscillating current component.
1 . A device including:
a current loop;
a component under test coupled within the current loop;
a variable impedance circuit coupled to receive at least a portion of a current of the current loop; and
frequency response analyzer circuitry coupled to the component under test and the variable impedance circuit outside the current loop, the frequency response analyzer circuitry configured to:
drive the variable impedance circuit to generate a time-varying impedance to cause an oscillating current component in the current of the current loop, the oscillating current component characterized by a test frequency; and
perform impedance spectroscopy by:
varying the test frequency; and
while varying the test frequency, monitoring a frequency response of the component under test to the test frequency.
2 . The device of claim 1 , where a magnitude of the oscillating current component is a perturbation to a total current in the current loop.
3 . The device of claim 1 , where the variable impedance circuit includes a static base load and a variable perturbative load.
4 . The device of claim 1 , a path of the frequency response contributes a phase shift in the frequency response with respect to the oscillating current component.
5 . The device of claim 4 , where the phase shift includes a 180 degree phase shift.
6 . The device of claim 4 , where the phase shift includes a phase shift due to a direction of current flow of the frequency response along the path with respect to a direction of the oscillating current component.
7 . The device of claim 4 , where the frequency response analyzer circuitry is further configured to perform the impedance spectroscopy by accounting for the phase shift in a frequency response analysis.
8 . The device of claim 4 , where the path includes a phase shifter configured to compensate for the phase shift.
9 . The device of claim 4 , where a driving signal for the oscillating current component from the frequency response analyzer circuitry is phase-shifted before provision to the variable impedance circuit to compensate for the phase shift.
10 . The device of claim 4 , where one or more response monitoring leads between component under test and the frequency response analyzer circuitry are reversed in polarity relative to a polarity defined for the oscillating current component.
11 . A method including:
driving a variable impedance circuit to generate a time-varying impedance to cause an oscillating current component in a current of a current loop, the variable impedance circuit coupled to receive at least a portion of the current of the current loop, the oscillating current component characterized by a test frequency; and
performing impedance spectroscopy by:
varying the test frequency; and
while varying the test frequency, monitoring, using frequency response analyzer circuitry, a frequency response of a component under test within the current loop to the test frequency.
12 . The method of claim 11 , where a magnitude of the oscillating current component is a perturbation to a total current in the current loop.
13 . The method of claim 11 , where driving the variable impedance circuit includes generating a static base load and a variable perturbative load.
14 . The method of claim 11 , a path of the frequency response contributes a phase shift in the frequency response with respect to the oscillating current component.
15 . The method of claim 14 , where the phase shift includes a 180 degree phase shift.
16 . The method of claim 14 , where the phase shift includes a phase shift due to a direction of current flow of the frequency response along the path with respect to a direction of the oscillating current component.
17 . A device including:
centralized frequency response analyzer circuitry multiplexed to multiple current loops each including a respective component under test; and
a multiplexer coupled to the centralized frequency response analyzer circuitry, the multiplexer configured to multiplex the centralized frequency response analyzer circuitry to multiple components under test each within respective current loops,
wherein the centralized frequency response analyzer circuitry is configured to, for each of the multiple components under test:
drive a variable impedance circuit to generate a time-varying impedance to cause an oscillating current component in the respective current loop, the oscillating current component characterized by a test frequency; and
perform impedance spectroscopy on the component under test by:
varying the test frequency; and
while varying the test frequency, monitoring a frequency response of the component under test to the test frequency.
18 . The device of claim 17 , where each of the multiple components under test are coupled to the multiplexer via an individual dedicated test station; and
the variable impedance circuit includes a centralized variable impedance circuit.
19 . The device of claim 18 , where each individual dedicated test station includes a parallel circuit coupling to the centralized variable impedance circuit.
20 . The device of claim 17 , where a path of the frequency response contributes a phase shift in the frequency response with respect to the oscillating current component.