31G 



THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1956 



and C = 0.1 microfarads. For these circuit values, and K = 10,000 

 (corresponding to 80 db of feedback) the nonhnear terms are less than 

 1/8,000 of the linear term (evaluated when / = 4 X 10"^ seconds) if 

 /i ^ 30 cycles per second, J2 ^ 800 cycles per second, and if the first 

 1000 microseconds of the voltage ramp are not used. Consequently, 80 

 db of negative feedback must be maintained over a band extending from 

 30 to 800 cycles per second in order to realize the desired output voltage 

 linearity. 



4.2. Detailed Circuit Arrangement 



Fig. 13 shows the circuit diagram of the integrator. The method of 

 biasing is the same as is used in the summing amplifier. The 200,000-ohm 

 resistor provides approximately 0.5 milliamperes of collector current for 

 the first stage. The 40,000-ohm resistor provides approximately 0.9 

 milliamperes of collector current for the second stage. The output stage 

 is designed for a maximum power dissipation of 120 milliwatts and for 

 an output voltage swing between —5 and +24 volts when operating 

 into a load resistance equal to or greater than 40,000 ohms. 



J+'08V 



• + 108V 



42 K 



D2 



44- 



C 



0.01>(/F o.l/iF 



2.4K 



270 K 



I 



+ I08V 



1MEG 



200n 



\ — vw 



2>U.F 



200 K 



rVWA/^An 



j 100 K [ 



POT. I 



I 



OUT 



-10.5V 



+ 108V 



+ 4.5V 



•45V -10.5V 



Fig. 13 — Integrator. 



