MT-032| Application Note

MT-032 TUTORIAL
Ideal Voltage Feedback (VFB) Op Amp

INTRODUCTION The op amp is one of the basic building blocks of linear design. In its classic form it consists of two input terminals, one of which inverts the phase of the signal, the other preserves the phase, and an output terminal. The standard symbol for the op amp is given in Figure 1. This ignores the power supply terminals, which are obviously required for operation.

(+)

INPUTS

(-)

Figure 1: Standard Op Amp Symbol The name "op amp" is the standard abbreviation for operational amplifier. This name comes from the early days of amplifier design, when the op amp was used in analog computers. (Yes, the first computers were analog in nature, rather than digital). When the basic amplifier was used with a few external components, various mathematical "operations" could be performed, such as addition, integration, etc. One of the primary uses of analog computers was during World War II, when they were used for plotting ballistic trajectories. See Reference 2 for more history of op amps. IDEAL VOLTAGE FEEDBACK (VFB) MODEL The classic model of the ideal voltage feedback (VFB) op amp has the following characteristics: 1. 2. 3. 4. 5. Infinite input impedance Infinite bandwidth Infinite voltage gain Zero output impedance Zero power consumption

Rev.0, 10/08, WK

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