Today, design engineers are compelled to use many capacitors in the power network to attenuate high-frequency digital noise. Circuits are designed to expect pure, clean power without noise that will impact analogue circuits. In a voltage regulator, capacitors are placed at the input and output terminals, between those pins and ground (GND).
High value polarised capacitors typically do not have ideal characteristics at high frequencies (e.g. significant inductance), so it's fairly common to add a low value capacitor in parallel in situations where you need to worry about stability at high frequencies, as is the case with 78xx regulator ICs such as this.
If the elements were connected in parallel, these relationships would invert; θ = +90° would indicate a capacitive element, while θ = -90° would indicate an inductive element. The characteristics of several types of common capacitors are presented in the table below:
In a voltage regulator, capacitors are placed at the input and output terminals, between those pins and ground (GND). These capacitors’ primary functions are to filter out AC noise, suppress rapid voltage changes, and improve feedback loop characteristics.
They are also used as bulk energy storage, providing instantaneous current to either the input or the load, as needed by design. Capacitors are critical components to all voltage regulator circuits. The dielectric material, and the physical design structure, used to manufacture different types of capacitors, give them different characteristics.
The voltage ( Vc ) connected across all the capacitors that are connected in parallel is THE SAME. Then, Capacitors in Parallel have a “common voltage” supply across them giving: VC1 = VC2 = VC3 = VAB = 12V In the following circuit the capacitors, C1, C2 and C3 are all connected together in a parallel branch between points A and B as shown.