| 摘要 |
<p>PROBLEM TO BE SOLVED: To highly accurately detect an amplitude of an input signal having a high frequency.SOLUTION: An amplitude detection circuit 11 is a signal amplitude detection circuit detecting a peak value of an input differential signal and detecting an amplitude of the input differential signal on the basis of the peak value, and includes a differential circuit 23 having a differential transistor pair 21a and 21b receiving the input differential signal and in which a current source 25a is connected to both emitter terminals of the differential transistor pair 21a and 21b; a hold capacitor 27 connected to both the emitter terminals of the differential transistor pair 21a and 21b and generating a hold potential equivalent to the peak value; a switch 29 connected between the emitter terminals of the differential transistor pair 21a and 21b and a current source 25b; and a level detection circuit 37 detecting the level of the input differential signal. The switch 29 becomes conductive only when the level detected by the level detection circuit 37 exceeds a level lower than the hold potential by a predetermined amount.</p> |
