| 摘要 |
PURPOSE: A tuning circuit of a gain control filter is provided to be capable of controlling the tuning voltage of a filter regardless of a process and temperature, and of reducing a chip size and consumption power by embodying a simple circuit. CONSTITUTION: A gain control cell(201) of a tuning part(200) outputs a gain controlled current in according to a tuning voltage. A switched capacitor(C1) is charged/discharged by current from the gain control cell(201) in accordance with the switching status of a switch and an inversion switch. An amplifier(202) amplifies the inversion voltage output from the capacitor(C1). A comparator(203) compares the amplified voltage with a reference voltage to output a comparison voltage. An adder(204) adds a default tuning voltage of the gain control cell(201) to the comparison voltage to output a tuning voltage(Vtune).
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