Patent ID: 6683925
Filing Date: 2004-01-27
Classification: H03G

Abstract:
A wireless terminal device comprising:a variable gain circuit having a variable gain and receiving a received signal; a first level detecting circuit having a widely selected input voltage range and detecting a level of the received signal supplied to said variable gain circuit; a converting circuit converting an output signal from said variable gain circuit into a digital signal; a second level detecting circuit detecting a level of an output signal from said converting circuit; and a controlling circuit coarsely controlling the gain of said variable gain circuit based on a detection output of said first level detecting circuit at a start of an operation then, finely controlling the gain of said variable gain circuit based on a detection output of said second level detecting circuit and, adjusting the output signal from said variable gain circuit such that the output signal from said variable gain circuit falls within an input voltage range of the converting circuit and is detectable with a resolution; wherein said first level detecting circuit includes a logarithmic amplifier; and wherein said controlling circuit supplies power to said logarithmic amplifier at the start of the operation and stops or reduces the power supply to said logarithmic amplifier at a normal-state.