| 摘要 |
PURPOSE: A GSM noise detector and filtering including a detection circuit is provided to freely use an accessory by using an audio jack detection switch. CONSTITUTION: First and second comparators(125,126) compare the extreme value of a four-pole audio jack with first and second threshold. First and second comparators supply the output showing a comparison result. A detection circuit(118) counts the change of the output for first duration. The detection circuit detects a GSM noise by using the count. The output of the first and second comparators three kinds of states. |
