| 摘要 |
PROBLEM TO BE SOLVED: To provide a gm-C filter system having low consumption power. SOLUTION: An adjusting circuit 2 has an oscillator 3, having therein a gm amplifier 3a which is constituted the same as an gm amplifier 1a of a gm-C filter circuit 1, and generates a digital adjusting value Dgm for adjusting the gm value of the gm amplifier 3a of the oscillator 3, based on an oscillation signal OSC outputted from the oscillator 3. The digital adjusting value Dgm is held in a register 10. The digital adjusting value Dgm, held in the register 10 is so converted into an analog adjusting value (a bias current) by a D/A converter so as to feed it to the gm amplifier 1a of the gm-C filter circuit 1 and adjust the gm value of the gm amplifier 1a. The adjusting circuit 2 is made to operate intermittently, e.g. based on the change of the ambient temperature of a gm-C filter system.
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