| 摘要 |
<p>The present invention is a time-constant detecting circuit incorporated in a LSI, for detection of the variations of component values of resistors and capacitors in the LSI as the variations of a time constant. A pseudo-resistor iscomposed of a switched-capacitor circuit. Two analog switches are switched on and off alternately in a period T to control charging and discharging of a capacitor. With the operation of the capacitor having a capacitance C, there is formed a pseudo-resistor of a resistance Rp = T/C. A predetermined DC voltage Vout is divided bya series circuit of the pseudo-resistor and an ordinary resistor, and is smoothed by a second capacitor. Output voltage Vout, smoothed and allowed to appear at the output terminal, is uniquely defined by a time constant variations of the time constant formed with the resistors and capacitors in the LSI can be detected by a measurement of the output voltage Vout.</p> |
