| 摘要 |
<p>The present invention is to provide a time constant detecting circuit incorporated in an 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 6 composed of a switched capacitor circuit. Analog switches 1 and 3 are exclusively switched on and off alternately in a period of T [sec] to control acapacitor 2 to be charged and discharged. With the operation of the capacitor 2 having a capacitance C, there is formed a pseudo-ressitor 6 of a resistance Rp= T/C, prdetermined DC voltage Vout is divided by a series circuit of the pseudo-resistor 6 and an ordinary resistor 4, and smoothed by a caspacitor 5. Output voltage Vout smoothed and allowed to appear at the output terminal 7 is uniquely defined by a time constant tau =1/RC, so that the 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. <IMAGE></p> |
