Frequency characteristic of shunt capacitance circuit diagram

Published:2011/7/16 9:39:00 Author:Sophia | Keyword: Shunt capacitance, Frequency characteristic | From:SeekIC

Power supply decoupling circuit usually adopts shunt capacitance and choose the optimum capacity and variety according to the frequency band of the circuits. Especially in high frequency circuit, shunt capacitance can reduce the power supply impedance, so the choice of the capacitor should choose deliberately. The diagram is the impedance and frequency chacateristic of ceramic capacitor. Theoretically, the capacitor impedance is 1/(2πfC). But the higher capacitance, the higher frequency, the lower impedance. because of the influence of the internal impedance, in excess of regular frequency, the impedance of the real capacitor will be higher on the contrary. So when the impedance reach the lowest point, the capacitance will be low and the frequency will be the highest. In the diagram a and b, when the capacitance is 10000pF, the frequency is 10MHZ; when the capacitance is 1000pF, the frequency is 40MHZ. When the frequency is high, shunt capacitance adopts low capacity capacitance, which will have better effect than high capacity.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Signal_Processing/High_Frequency_Signal_Generating/Frequency_characteristic_of_shunt_capacitance_circuit_diagram.html

Print this Page | Comments | Reading(3)