Figure 2-12 shows a voltage follower. The voltage follower can be regarded as a noninverting amplifier with an R1 of infinite resistance and an R2 of zero. Since the voltage follower has a low gain (unity gain, AV=1), it has a wide bandwidth. Therefore, care should be taken since it is susceptible to the effect of a second pole as discussed in Section 2.3, “Oscillation.” Most op-amps can be used as unity gain amplifiers since they have a second pole at a frequency sufficiently higher than the unity gain cross frequency (fT). However, they might go into oscillation because of wire or load capacitance. If the datasheet for a given op-amp states that it can be used at a unity gain, it can be used as a voltage follower. Contact Toshiba’s sales representative if you want to use any other op-amp as a voltage follower.
In addition, op-amps have various applications, including a differential amplifier (subtraction circuit) as well as an adder and integrator circuits.