Circuit for controlling input signal of power amplifier

The present invention relates to an input signal control circuit of a power amplifier for safely protecting the power amplifier against an abnormal input signal and stably driving the power amplifier. The input signal control circuit of the power amplifier prevents the power amplifier from being damaged due to an unstable clock and the malfunction of a CFR block in a digital signal process or excessive input caused by the malfunction of a signal source. The input signal control circuit of the power amplifier protects the power amplifier for a protection time consumed for determining the excessive input and limits the protection time below a specific threshold to prevent quality problems of a call due to the increased protection time in the entire system. [Reference numerals] (200) Signal level detecting unit; (300) Comparing unit; (400) Directional coupler; (500) Group delay filter; (600) Negative group delay circuit