Patent ID: 6252457
Filing Date: 2001-06-26
Classification: H03F

Abstract:
A differential amplifier circuit for treating a signal in which an ac voltage signal is superimposed on a dc voltage, wherein:two terminals of a signal source are respectively connected to bases of a first NPN transistor and a second NPN transistor;emitters of said first NPN transistor and said second NPN transistor are respectively connected to collectors of a third NPN transistor and a fourth NPN transistor;emitters of said third NPN transistor and said fourth NPN transistor are commonly connected, and further connected to a first power source through a constant current source;the collectors and bases of said third NPN transistor and said fourth NPN transistor are respectively connected through first and second capacitors;the bases of said third NPN transistor and said fourth NPN transistor are respectively connected to a first reference power source through first and second resistors; andcollectors of said first NPN transistor and said second NPN transistor are respectively connected to a second power source through third and fourth resistors, and respectively connected to output terminal.