TRANSISTOR PULSE REGENERATIVE AMPLIFIERS 1113 



0.2 mh for T2 together with a turns ratio of 1.4 for Tl are selected. Since 

 the GA-52996 transistor is not quite short circuit staple, a 50-ohm 

 resistor is added in series with the emitter. The excess emitter current 

 at the end of the pulse duration is greater than 2 ma, thus assuring suffi- 

 cient stability, and, if the clock fails, the amplifier will turn off by itself 

 in approximately 7 jusec, at which time the instantaneous collector dissi- 

 pation will be approximately 240 mw (considered to be a safe instan- 

 taneous dissipation for this transistor). 



For low clock power and circuit simplicity the single diode synchroniz- 

 ing circuit is chosen. Although a peak clock voltage of 2 volts would nor- 

 mally be used (this value corresponds to the quiescent emitter bias volt- 

 age) it is found that the clock may be varied between 1 volt and 6 volts 

 peak without a failure occurring. Therefore, the nominal clock voltage 

 is set at a centered value of 3 volts peak. The dc level of the clock voltage 

 is volts, which approximately corresponds to the emitter break point 

 voltage of the transistor. This concludes the basic selections in the de- 

 sign procedure. 



The power dissipated in the amplifier is quite modest. In the quiescent 

 state the amplifier absorbs only 0.2 mw average clock power and 30 mw 

 dc power (this would be only 10 mw if the I co power w'ere negligible). 

 When the amplifier is pulsing every microsecond the dc power is 50 mw 

 and the averge clock power is 2 mw. Since the amplifier is so conser- 

 vative of power, it is possible to use 4,000 networks in a computer and 

 require less than 200 watts dc power. 



One indication of the component sensitivity of a pulse amplifier is the 

 magnitude of the supply voltage margins. In this amplifier the supply 

 voltages may be varied, one at a time, over ±12 per cent of the nominal 

 values before a failure occurs. Generally margins of this magnitude under 

 the worst conditions are considered sufficient to guarantee against fail- 

 ures caused by aging, or to insure that such failures will be indicated by 

 routine checks before they occur. It is interesting to note that in a tem- 

 perature test the amplifier continued to operate properly over a tempera- 

 ture range from —20 to +80°C. Even at -f75°C the supply voltage 

 margins were 10 per cent or better. 



8. SUMMARY 



A method of analysis and design procedure have been presented in 

 which a transistor regenerative amplifier is considered as an intercon- 

 nected system of functional circuits. Each functional circuit may be 

 evaluated or chosen in terms of the requirements of the complete digital 

 system in which the amplifier is to be used. In general no particular cir- 



