| 摘要 |
PURPOSE:To decrease number of bits of an A/D converter and to lower the power supply voltage and also to decrease the current consumption by providing a function operating at most one of double balanced differential amplifiers. CONSTITUTION:The number of stages of differential amplifiers constituting an intermediate frequency amplifier is selected as n=4(=2<2>) stages. In selecting each resistance properly, the circuit constitution is 4-stage connection of identical differential amplifiers and double balanced differential amplifiers. In order to realize the differential amplifier and the double balanced differential amplifier, nearly 2.5V is made possible for a power voltage Vcc. Thus, in the circuit constitution in figure, the power supply voltage of Vcc=2.5V is realized. Further, as to the current consumption, when reception electric field information is required and a switch Si (i=1, 2, 3, 4) detecting the reception electric field strength required in the specific dynamic range is selected, one current flowing is enough in the 4 double balanced differential amplifiers and since a current I0 is reduced to 1/4, the current consumption is reduced remarkably.
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