| 摘要 |
PURPOSE:To reduce the pin number of a semiconductor integrated circuit and the number of peripheral parts by constituting to enlarge and input impedance in an input point sufficiently and integrating an amplifier and an input high impedance bias circuit into one body. CONSTITUTION:An amplifier 34 consists of an input signal terminal 16, a coupling capacitor 17, NPN transistors 18 and 19, resistance 20, 21, 23 and 24, a constant current source 22 and a constant voltage power source 25. An input bias circuit consists of a constant current source 26, an NPN transistor 27, PNP transistors 28, 31 and 32 and resistance 29 and 30. On making into a semiconductor integrated circuit, the transistor, the resistance, etc., can be balanced- manufactured. The input impedance of an input point 35 becomes the parallel resistance of the input impedance of the base of the transistor 18 and the input impedance of the base of the transistor 31. By this constitution, a high input impedance amplifier which builds in the coupling capacitor inside an integrated circuit and can amplify the signal of the frequency of several tens kHz. |
