| 摘要 |
PURPOSE:To suppress a variation of a clamp voltage level caused by an input signal voltage by applying a signal to be clamped to an output part of a buffer circuit through a resistance, and fetching a clamp output from its output part. CONSTITUTION:A differential amplifier 44 of a buffer circuit 22 is formed by connecting a load consisting of transistors 80, 82 for constituting a current mirror circuit, to a differential amplifier consisting of a pair of transistors 76, 78 whose emitters are common, and also adding a transistor 66 and a transistor 84 for constituting a current mirror circuit, and its operating current is applied from a constant-current source 58. A buffer circuit 24 is also the same, and its operating current is applied from the constant-current source 58. An output is fetched from a collector of transistors 88, 92, and provided to a base of a transistor 50. In this way, a stable clamp voltage can be set, a clamp output of high accuracy can be obtained, and also the operation can be stabilized. |
