Prescaler circuit and buffer circuit

摘要

A prescaler that operates in a broad band. The prescaler (33) includes a buffer (41) and a counter (43). The buffer includes a first amplification circuit (50), which has three inverter circuits (52a, 52b, 52c) of different drive capacities, a second amplification circuit (54), which has four series-connected inverter circuits (54a, 54b, 54c, 54d), and a feedback circuit (55). One of the inverter circuits (52a, 52b, 52c) is connected between a capacitor (C1) and an inverter circuit (54a) via a first switch circuit (51) and a second switch circuit (53). This varies the drive capacity of the first amplification circuit (50). The feedback circuit (55) functions as a variable resistor having two transistors (T1, T2).