Operational Amplifier

The circuit

Due to the need for high frequency stability, linearization through the use of negative feedback may not be enforced arbitrarily. Because of this, operational amplifiers are furnished with a linear open loop transfer characteristic. One of the first applications of the operational amplifier was to solve mathematical operations in analog computers with high accuracy. The op-amp was desirable because of its linearity and stability at high frequencies. Today, op-amps are found in nearly all types of analog circuits. They are mass produced as inexpensive monolithic circuits and come in a wide variety of performance characteristics.

The input file (operational_amplifier.cir)

operational amplifier

.control
dc v1 -100mV 100mV 1mV
plot v(6) xlabel v1[V] ylabel 'output voltage [V]' title 'DC analysis'
.endc

v- 4 0 dc -15V
v+ 7 0 dc 15V
v1 2 0 dc 0

r1 7 6 1k
r2 7 1 36k
r3 5 4 18k

q1 4 2 1 noname1
q2 5 0 1 noname1
q3 6 5 4 noname2

.model noname1 pnp
.model noname2 npn

.end

Results