Asia-Pacific
English
简体中文
繁體中文
한국어
日本語
Americas
English
Europe (EMEA)
English



Part Number Search

Cross Reference Search

About information presented in this cross reference

The information presented in this cross reference is based on TOSHIBA's selection criteria and should be treated as a suggestion only. Please carefully review the latest versions of all relevant information on the TOSHIBA products, including without limitation data sheets and validate all operating parameters of the TOSHIBA products to ensure that the suggested TOSHIBA products are truly compatible with your design and application.
Please note that this cross reference is based on TOSHIBA's estimate of compatibility with other manufacturers' products, based on other manufacturers' published data, at the time the data was collected.
TOSHIBA is not responsible for any incorrect or incomplete information. Information is subject to change at any time without notice.

Keyword Search

Parametric Search

Stock Check & Purchase

2.4. Basic op-amp applications

In the most basic form, op-amps are used as noninverting amplifiers (Figure 2-10) and inverting amplifiers (Figure 2-11). Both noninverting and inverting amplifiers have negative feedback (with the output connected to VIN(-)) as described in the previous section.
The closed-loop gain (ACL) is shown in the following figures. The gain can be calculated easily by using the concept of a virtual short-circuit (also known as a virtual short, virtual ground or imaginary short) described in the next section.
The noninverting amplifiers have a very high input impedance since their input is directly connected to an op-amp. In contrast, the input impedance of the inverting amplifier is lower than that of the noninverting amplifier because VIN(-) and VIN(+) have the same potential as they are virtually short-circuited and because R1 acts as input impedance.

Figure 2-10 Noninverting amplifier
Figure 2-10 Noninverting amplifier
Figure 2-12 Voltage follower
Figure 2-12 Voltage follower
Figure 2-11 Inverting amplifier
Figure 2-11 Inverting amplifier

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.

Figure 2-13 Differential amplifier (subtraction circuit)
Figure 2-13 Differential amplifier (subtraction circuit)
Figure 2-15 Integration circuit
Figure 2-15 Integration circuit
Figure 2-14 Addition circuit
Figure 2-14 Addition circuit

Related information

Chapter2 Using an op-amp

2. Using an op-amp
2.1. Feedback (positive and negative feedback)
2.2. Open-loop and closed-loop gains (Increasing the bandwidth of an amplifier)
2.3. Oscillation
2.5. Virtual short (virtual ground)

Related information