Patent ID: 6292032
Filing Date: 2001-09-18
Classification: H03F,H03H

Abstract:
A high impedance circuit comprising:a first transistor;a first resistance element connected between a collector of the first transistor and a first voltage power supply line;a first current source connected between an emitter of the first transistor and a second power supply line (ground);a second transistor having a same conductivity as the first transistor;a second resistance element connected between a collector of the second transistor and the first voltage power supply line and having a resistance value same as that of the first resistance element;a second current source connected between an emitter of the second transistor and the second power supply line (ground) and being equal to the first current source;a third resistance element connected between the emitter of the first transistor and the emitter of the second transistor;a third transistor, having a base connected to a collector of the second transistor and an emitter connected to a base of the first transistor, said third transistor having the same conductivity of the first transistor;a fourth transistor, having a base connected to a collector of the first transistor and an emitter connected to a base of the second transistor, said fourth transistor having the same conductivity of the second transistor;a fourth resistance element connected to a collector of the second transistor and to a base of the first transistor, anda third fixed current source circuit connected to the fourth resistance element and the base of the first transistor and the second voltage source, anda fifth resistance element connected between a collector of the first transistor and the base of the second transistor, and having a same resistance value to the fourth resistance element, anda fourth fixed current source circuit connected to the fifth resistance element and a base of the second transistor and the second voltage source, and being equal to the third current source.