1102 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 



diode breakdown voltage reduce amplifier margins, and pulse inversion 

 is not possible. For these reasons diode coupling has limited utility, but 

 is attractive for some applications. 



5.2 Connection of Output and Feedback Circuits 



The performance of the amplifier is greatly affected by the method used 

 to connect the output circuit and the feedback circuit together at the | 

 output of the transistor. Should these two circuits be connected in a 

 shunt or a series fashion? Performance features, such as rise time, suf- 

 ficient output voltage, degree of stabihty versus load current variations, 

 and power dissipation directly depend upon this choice. With transformer 

 output coupling, the choice always exists; with other types of output 

 coupling the choice may or may not exist, depending upon the type of 

 feedback coupling. The following discussion is in terms of transformer 

 coupled output and feedback circuits and the general conclusions may 

 be extended to other cases. 



Y\ . t-- 



OUTPUT OF 

 AMPLIFIER 



_!_ 



(a) CONNECTION OF AMPLIFIER LOAD 



■nl. 



I 

 T 



(b) V-I CHARACTERISTIC OF AMPLIFIER LOAD 



Fig. 10 — Output load characteristic. 



