Using integrator to measure capacitance

[slugrustle]

Are there any capacitance measurement instruments that use an integrator to measure capacitance?  The idea would be to use the unknown capacitor as the integrator capacitor, connect the integrator input to a very accurate current source, and measure the slope of the integrator output voltage.  It's almost like the inverse or complement of a multi slope ADC.

Granted, this would only measure capacitance at DC with 0V bias.  I'm just curious if it has been done before or if there are reasons why it would be hard to make accurate.  In particular, I'm thinking the integrator output voltage slope measurement might be tricky to perform accurately.

On the other hand, if you want to measure a capacitor that is intended for use in an integrator, this would be a great way to do it, as opposed to an AC capacitance bridge or whatever.

[Conrad Hoffman]

Can't name any specific instruments but I'm pretty sure some inexpensive ones work this way. It's not a bad method if you don't have much to work with but doesn't give you losses and is subject to DC leakage of the cap. Integrator capacitors can be sensitive to dielectric absorption; Bob Pease wrote some stuff on this.
https://www.electronicdesign.com/technologies/analog/article/21796328/electronic-design-whats-all-this-soakage-stuff-anyhow
https://www.edn.com/wp-content/uploads/2016/11/1982-10-13_EDN_Pease-capacitor-soakage.pdf
https://www.electronicdesign.com/technologies/analog/article/21796004/use-analog-techniques-to-measure-capacitance-in-capacitive-sensors
http://www.ecircuitcenter.com/Circuits/DMM%20Cap/DMM_cap_1.html
https://www.metrohm.com/content/dam/metrohm/shared/documents/application-notes/an-e/AN-EC-012.pdf

Those links should keep you off the streets and out of the pool halls for a while. 

[MegaVolt]

Many multimeters measure capacitance this way. They have a current source for changing resistors. If you apply it to a capacitor, you will get a measurement ))

For example DMM6500, DMM7510

[tszaboo]

You can build this. The biggest error source is the offset voltage in the system, that gets integrated, so you might need to compensate that out before each measurement, or use dual slope or other methods that are less susceptible for those errors.