[sdiy] differential integrators?

[dan snazelle]

last night, for the first time in months, i found some time to just sit and read electronics books.

i came across a term i hadn't thought much about before: Differential Integrator


However, one of the examples in the OPAMP cookbook used a variable capacitor which i would like to avoid if i could. the other used two opamps and a few matched resistors

so my questions are

1. what are some good uses for differential integrators

2.  where are some good examples of how to build them?

3. do they always have to use matched caps and resistors


thanks so much!