Unit transistor amplifier with matched input and output impedances

Abstract

An amplifier having a combination of local series and shunt feedback to provide matched input and output impedances permitting cascading of a number of amplifiers or amplifiers and other devices without signal degradation. .Iadd.

We claim:  .[. 
     
       1.  An amplifier including a transistor having base, emitter and collector terminals, means for applying an input signal between the base and emitter terminals, and means for deriving an output signal between the collector and emitter terminals in which there is provided shunt feedback resistance means between the output and input means and resistance means in series with the emitter current path providing series feedback, said shunt feedback resistance means and series feedback resistance means being selected to provide predetermined and equal input and output impedances and a predetermined gain whereby said amplifier has a predetermined characteristic impedance determined solely by the square root of the product of said shunt and series feedback resistance means..]. 
     
     
       2. An amplifier as in claim .[.1.]. .Iadd.6 .Iaddend.including means connected between the base and collector terminals of said transistor for stabilizing the operating point of said transistor. 
     
     
       3. An amplifier as in claim 2 wherein said means comprises a transistor having its emitter and collector terminals connected between the base and collector of said transistor to control the .[.base and collector of said transistor to control and.]. base current of said transistor. 
     
     
       4. An amplifier as in claim 2 including blocking capacitor means connected in series with the base and collector terminals of said transistor and a compensating circuit including an inductance series connected to said collector terminal and a capacitance shunt connected to said collector terminal.  .[.5. An amplifier as in claim 1 wherein: ##EQU4## where R f  =feedback resistance between collector and base of said transistor R e  =resistance in series with emitter lead of said transistor   R b  =signal source impedance   R l  =load impedance   Z in  =input impedance   Z out  =output impedance   I 1  =input current   I 2  =output current   I 2  /i 1  =gain in which R f , R e , R b  and R L  are selected to provide:   Z.sub.in =Z.sub.out =R.sub.o and R.sub.L =R.sub.b =R.sub.o     whereby     R f  R e  =R 2   o  , the characteristic impedance and ##EQU5##   
     
     
        the gain..]. .Iadd. 6.  An amplifier having a characteristic impedance R o  wherein the signal source impedance R b  and the load impedance R L  are substantially equal to each other and to R o , said amplifier comprising a transistor having base, emitter and collector terminals, means for applying an input signal between the base and emitter terminals and means for deriving an output signal between the collector and emitter terminals in which there is provided shunt feedback resistance means between the output and input means and resistance means in series with the emitter current path providing series feedback, said shunt feedback resistance means and series feedback resistance means being selected to provide predetermined and equal input and output impedances and a predetermined gain independent of said equal input and output impedances wherein ##EQU6## and ##EQU7## where R f  = feedback resistance between collector and base of said transistor R e  = resistance in series with emitter lead of said transistor   R b  = signal source impedance   R L  = load impedance   Z in  = input impedance   Z out  = output impedance   I 1  = input current   I 2  = output current   I 2  /I 1  = gain   in which R f  and R e  are selected to provide the characteristic impedances:   Z.sub.in = Z.sub.out = R.sub.o =√R.sub.f R.sub.e       and the gain: ##EQU8## whereby the characteristic impedance of the circuit is determined by the product of R f  and R e  and the gain of the circuit is independently determined by the ratio of R f  and R e . .Iaddend.