Cars have severe environmental conditions, some of which result in pulse type noises. Examples are temperature, vibration, etc. and from the engine ignition high-voltage circuit and other electronic control circuits. In these severe circumstances, car radios need to be unaffected and reliable, in addition to being small in size, light in weight and convenient to operate. First of all, high performance and low cost are counted, life have developed the technology to eliminate offensive pulse type noises for improvement of sound quality needed for AM stereo broadcasting.