Electronic

1. AL-Mustansiriya university Computer &software Eng. department Electronic OP.Amplifiers

2. An amplifier,electronic Amplifier or(informally)amp is an electronic that can increase the power of signal(a time_varying voltage or current).An amplifier users electronic power from a power supply To increase the amplitude of a signal. The amount of amplification provided by an amplifier is measured by its gain. The ratio of output to input .An amplifier is a circuit that can give a power gain Greater than one.[1][2][3] . • Properitesof amplifier: • *Gain,the ratio between the magnitude of output and input signal. • *Band width, the width of the userful frequency range. • *Efficiency,the ratio between the power of the output and total power consumption. • *Linearity,theexten to which the proportion between input and output amplitude is same for high and low amplitude input. • *Noise ,a measure of undesired noise mixed into the output. • *Slew rate, the maximum rate of change of the output.

3. Operational amplifier(op_amps) An operational amplifiers(op-amps): is an amplifier circuit which typically has very high open loop gain and differential input. Op_ amps have become very widely used as standardized(gain blocks) in circuit due to their gain ,bandwidth and other characteristics can be controlled by feedback through an external circuit. Through the term today commonly applies to integrated circuits , the operational amplifier design used vales and later design used discrete transistor circuit . A fully differential amplifier is similar to the operational amplifier , but also has differential outputs. These are usually constructedusing BJTs or FETs . Three applications of amplifier: 1- Video amplifier. 2-Microwave amplifier. 3-Musical instrument amplifier.

4. Summing amplifier You can use summing amplifier to combine multiple signal by addition or subtraction. Since the difference amplifier can only process two signal it is subset of the summing amplifier. The transfer function of this circuit as shown in figure at right: Vout = (V1+V2-V3-V4)(R2/R1) You can use any number of inputs on either the inverting or Non inverting input sides as long as there are an equal number of both with equivalent resistors . All of the inputs to this circuit should be connected to signal source or (if unused) to the ground.

5. Example amplifier circuit The practical amplifier circuit to right could be the basis for a moderate –power audio amplifier .It features a typical (though Substantially simplified)design as found in modern amplifiers. With Class _AB push –pull output stage ,and uses some overall negative feedback . Bipolar transistors are shown ,but this design would also be realizable with FETs or vales. The input signal is coupled through capacitor CI to the base of Transistor QI. The capacitor allows the AC signal to pass . but blocks the DC bias voltage established by resistors R1,R2 so that any preceding circuit is not affected by it .Q1 and Q2 form a differential amplifier(an amplifier that multiplies the difference between two inputs by some constant). in an arrangement known as a long –tailed pair .This arrangement is used to conveniently allow the feedback ,which is fed from the output to Q2 via R7 and R8 .

6. Complete of amplifier circuit

7. The Difference amplifier The difference amplifier combines the non inverting Amplifier and inverting amplifier circuit into signal block that subtract two signal . A difference amplifier or op-amp subtractor uses this arrangement of resistor around an amplifier . The DC transfer function of this circuit is equal to: Vout =V in+ *(R4*(R1+R2))/(R1*(R3+R4))_Vin-*(R1/R2)+V shift*R3(R1+R2)/((R3+R4)R1).

8. Figure of perfect amplifier