If you are talking about feedback control system (Closed loop controls), then look at Matlab/Simulink modeling and samples. There are many available, if you have access to Matlab. If you are talking about electronic circuits(Opamp based/discretes), analog IC design, googling helps.

• Any case studies needs to do firstly a related Systems  Analysis. Based on this Analysis you are able to do the conceptual mathematical model associated. This model is, in the general case, decomposed into sed of submodels and a  complementary mocel for all system decisions conciliation. After you need to elaborate the detailed associated modellling  (models parametrization). In the third etap you must to select procedures for solving every model, including the conciliation one. You can find a breaf description of related metodology in my work "Analysis and Sinthesis of Engineering Systems" in my researchgate profiil page, Best wishes, José Arzola-Ruiz

Read the book "Modeling and Analysis of Dynamic Systems" by R.S. Esfandiari and Bei Lu, published by CRC Press. The second edition contains more about using MATLAb-sIMULINK with worked examples