DECOUPLING CAPACITANCE CHANGE CIRCUIT, ESPECIALLY ONLY CHANGING THE TEST SIGNAL TO IMPROVE A POWER NOISE IMMUNITY

摘要

PURPOSE: A decoupling capacitance change circuit is provided to control the decoupling capacitance by using only the change of the test signal without correcting the metal layer circuit in controlling the decoupling capacitance to improve the power noise immunity. CONSTITUTION: A decoupling capacitance change circuit includes a decoder(210) and a capacitance adjustment circuit(220). The decoder(210) receives an address signal, a test mode generation signal and the test mode release signal and generates the capacitance change signal by the logic operation and the latching operation. And, the capacitance adjustment circuit(220) adjusts the decoupling capacitance between the power voltage and the ground voltage in response to the capacitance change signal.