| 摘要 |
PROBLEM TO BE SOLVED: To provide a direct conversion receiver that suppresses transient DC fluctuations, as much as possible, generated in an output from a high-pass filter, when the gain changeover of a gain control amplifier. SOLUTION: The direct conversion receiver has: the gain control amplifier variably amplifying a base-band signal on the basis of a gain-changeover control signal; a high pass filter having an input terminal inputting an output signal, an output terminal, a plurality of capacities connecting the input terminal and the output terminal, in series, a first time-constant changeover circuit changing over the capacity values of a plurality of the capacities on the basis of a first time-constant changeover control signal, a resistance supplying the output terminal with a specified DC voltage and, a second time-constant changeover circuit changing over the resistance value of the resistance on the basis of a second time-constant changeover control signal; and a control circuit outputting the gain changeover control signal of the gain control amplifier and outputting the first and second time-constant changeover control signals, in response to the gain changes. COPYRIGHT: (C)2006,JPO&NCIPI
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