For Third year Biophysics Special Students. Prepared by: Abdo A. Elfiky. Assistant Lecturer, Biophysics Department, Faculty of Science, Cairo University.

Introduction Integrated circuit (IC), Microcircuit, Microchip, semiconductor Silicon chip, or Chip) is a small electronic device made out of a semiconductor material. The first integrated circuit was developed in the 1950s. There are two main advantages of ICs over discrete circuits: cost and performance.

741 type op-amp (1968) IC 741 Biophysics department

Op-Amp positioning on the board IC 741 Biophysics department

Operational amplifier additionsubtraction integrationdifferentiation Op-amps were used to perform mathematical operations such as addition, subtraction, integration,and differentiation, hence the term operational. The op-amp has two input terminals, called the inverting input (-) and the non-inverting input (+), and one output terminal.

IDEAL OP-AMP

Open-Loop Voltage Gain A ol 1 volt 100,000 volts 1 volt

Closed-Loop Voltage Gain A cl Op-amp can be connected using negative feedback to stabilize the gain and increase frequency response. Negative feedback takes a portion of the output and applies it back out of phase with the input, creating an effective reduction in gain. This closed-loop gain is usually much less than the open-loop gain and independent of it.

Voltage Follower Used as a buffer amplifier to eliminate loading effects or to interface impedances (connecting a device with a high source impedance to a device with a low input impedance) 1 volt 100,000 volts -99,999 V

Voltage Follower

Non-Inverting Amplifier In a non-inverting op-amp, the input signal is applied to the non-inverting input (+). The output is applied back to the inverting input (-) through the feedback network formed by R i and R f.

1 volt 100,000 volts If Rf = Ri = 1KΩ, Then Vf = ½ Vout Acl = 100,000 / 49,999 = ~ ,999 V

Inverting Amplifier In an inverting op-amp, the input signal is applied through a series of input resistor R i to the inverting input. Also, the output is feedback through R f to the same input, The non-inverting input is grounded.

1 volt 100,000 volts - 50,001 V If Rf = Ri = 1KΩ, Then Vf = ½ Vout Acl = 100,000 / 50,001 = ~ 2

Procedure Procedure:- Non-inverting connection: 1. Connect the circuit of the non-inverting op-amp. [ R i (constant) = 1000  ; R f (variable) = 0.5K , 1k , 2k , 3k , 5.5k , 8K  and 10k  )]. 2. For each value of the R f find the closed loop gain A cl experimentally (V out /V in ), and theoretically ((R f +R i )/R i ). 3. Draw a relation between A cl and the values of R f experimental and theoretical.

Procedure Procedure:- Inverting connection: 1. Connect the circuit of the Inverting op-amp. [ R i (constant) = 1000  ; R f (variable) = 0.5K , 1k , 2k , 3k , 5.5k , 8K  and 10k  )]. 2. For each value of the R f find the closed loop gain A cl experimentally (V out /V in ), and theoretically (–R f /R i ). 3. Draw a relation between A cl (experimental and theoretical) and the values of R f.

Summing Amplifier

Procedure Procedure:- 1. Connect the circuit of the Inverting op-amp. [ R in1,R in2 are constant = 1000  ; R f (variable) = 1k , 2k , 3k , 5.5k , and 8K  ]. 2. For each value of the R f find the output voltage V out experimentally, and theoretically (–R f /R(V in1 +V in2 )). 3. Draw a relation between V out (experimental and theoretical) and the values of R f.

Thank you 11/5/200826prepared by: Abdo A. Elfiky