·         Operational Amplifier

If you have signal inputs (AC/DC) and need to be amplified, you can pick an operational amplifier (Op Amp).  Operational amplifiers are very versatile electronic devices. This is a sampling of the kinds of devices which can be created with a single op-amp. Figure 1 shows an Op Amp symbol.

Figure 1 Op Amp Symbol

Basically, there are two types of Operational Amplifier. 

1.        Inverting Amplifier

For an ideal op-amp, the inverting amplifier gain is given simply by :

Note:

R_i              : Resistor Input

R_f             : Resistor feedback

V_in            : Voltage Input

V_out          : Voltage Output

Figure 2. Inverting Amplifier Circuit

 Figure 3. Signal output inverted with inverting op amp

Sign “-“ in the equation means output signal is inverted from input signal, shown in figure 3. For equal resistors, it has a gain of -1, and is used in digital circuits as an inverting buffer.

2.        Non Inverting Amplifier

For an ideal op-amp, the non-inverting amplifier gain is given by

Figure. 4 Non Inverting Amplifier Circuit