In the name of allah

Operational Amplifier

OpAmp Properties The op amp obeys the input-output relationship: where vo is the output voltage, v+ and v- are, respectively, the voltages at the non-inverting and inverting inputs, and A is the amplifier gain. For an ideal op amp there are two important facts: a) The gain of the amplifier is infinite. b) The internal resistances between the inputs (v+ and v-) and ground are infinite. These two facts lead to two important relationships used to analyze op amp circuits: 1) The voltages at the two inputs are the same. 2) There is no current from the input of the op amp.

Operational Amplifier Circuits

Inverting Amplifier

Non-inverting Amplifier

Voltage Follower

Differential Amplifier

Summing Amplifier

Integrator

Differentiator

Current to Voltage Converter

comparator

Basic non-inverting comparator.

Voltage transfer characteristic

Voltage transfer characteristic

Ideal comparator

Inverting comparator and its voltage transfer characteristic.

Non-inverting comparator circuit

Input and output

Schmitt Trigger

Inverting Schmitt trigger. if we are able to specify a voltage range within which the state of the output can be at either value then we should be able to build the appropriate level of noise immunity. The conceptual representation of the idea is shown on next capture. In this case the alarm turns on at time t1 and turns off at time t2 avoiding all the chatter in between

Input and output

Voltage characteristic of inverting Schmitt trigger The voltage transfer characteristic shows that there is Hysteresis Effect. The width of the hysteresis region, V TU −VTL , corresponds to the noise immunity of the trigger circuit.

Voltage characteristic of inverting Schmitt trigger