| 摘要 |
<p>A frequency-variable filter has a GmC filter and a pseudo-random value generator, wherein the GmC filter has an input-side OTA for converting an input voltage of an input terminal to a current, a capacitor for generating an output voltage to an output terminal on the basis of an output current of the input-side OTA, and a feedback-side OTA provided between the output terminal and the input-side OTA, and has a cut-off frequency corresponding to the transconductance and the capacity value of the capacitor. Furthermore, a pseudo-random value generator generates pseudo-random values corresponding to an input setting value at a high frequency, and the average value within a predetermined amount of time of the pseudo-random values is taken as a value corresponding to the input setting value. In addition, for at least the feedback-side OTA, the transconductance is variably controlled according to the pseudo-random values, and the cut-off frequency is variably controlled on the basis of the input setting value.</p> |
