Crystal Oscilator


Joined Dec 26, 2010
Analog(ue) circuits can also have problems if there are no capacitors across the supplies to keep the impedances down, particularly at higher frequencies.

Sometimes these may be referred to as supply decoupling capacitors, the point being that the supplies can provide an unwanted route for couplings between circuits if such precautions are not taken.

Often this will result in a poor frequency response, or even oscillations. In battery powered equipment, this may only happen when the battery is partially discharged so that its internal resistance rises.

As a teenager, I once had a little radio that would go plop-plop-plop... when the battery got a bit weak. I was very pleased when I found out that adding a capacitor would let me go on using the battery until it was really dead.