There are several types of urgency in the ideal op amp working state

The open-loop magnification of an ideal op amp is infinity. So there are two kinds of working states, that is, linear and nonlinear. Because the open-loop amplification factor is infinite, the input voltage is theoretically infinitesimal in order to work.

Because the input voltage is infinitesimal, then the two inputs are equivalent to a short circuit, which is called imaginary short. And because the input voltage is infinitesimal, there is no current between the two inputs, which is called a false break.

It is linear when u->u+ and nonlinear when u+>u-.

1) When the signal is input from the non-inverting input terminal to the common ground terminal, the output voltage and the input voltage are in phase ,—— the in-phase input mode;

2) When the signal is input from the inverting input to the common ground, the output voltage is inverted with the input voltage ,—— inverting input mode;

3) When the signal is from the non-inverting input and the inverting input to the common at the same time.

In the case of ground input, the output voltage phase is determined by the two input voltages, which is the differential input mode.

1 Two kinds, linear and nonlinear, judgment method: if the integrated op amp introduces negative feedback, it is linear; If positive feedback or open loop is introduced, it is nonlinear.

2 Conditions: The open-loop differential mode voltage amplification factor is infinity, the differential mode input resistance is infinite, the output resistance is 0, the common-mode rejection ratio is infinity, the input bias current is 0, and the upper frequency is infinity.

3. Stabilize the amplification, widen the pass band, reduce nonlinear distortion and suppress interference, and change the input and output resistance.

4 Imaginary short: u+ = u- imaginary break: i+ = i- =0

Key Features of Ideal Operational Amplifiers:

1. Infinite input impedance (zin= ) The ideal input of the operational amplifier does not allow any current to flow in, that is, the current signal at the ends of V+ and V- in the above figure is always zero, that is, the input impedance is infinite.

2. Output impedance approaching zero (zout=0): The output of the ideal operational amplifier is a perfect voltage source, no matter how the current flowing to the amplifier load changes, the output voltage of the amplifier is always a certain value, that is, the output impedance is zero.

3. Infinite open-loop gain (AD= ) An important property of an ideal op amp is that in the state of open loop, the differential signal at the input end has an infinite voltage gain, which makes the op amp very suitable for adding negative feedback configuration in practical applications.

4. The ideal op amp with infinite common-mode rejection ratio (cmrr= ) can only respond to the difference between the voltages at the ends of V+ and V-, that is, only the part of V + V is amplified. For the same part of the two input signals (i.e., common-mode signals) they are completely ignored.

5. Infinitely large bandwidth: The ideal operational amplifier will amplify the input signal of any frequency with the same differential gain, and will not change due to the change of signal frequency.

Ideal integrated op amp means that all the indicators of the integrated op amp are ideal characteristic values. An ideal integrated op amp should have the following basic conditions:

The differential-mode voltage gain is infinite, i.e., aud,

The resistance of the person is infinite, that is, rid;

The output resistance is zero ro 0;

The common-mode rejection ratio is infinite, i.e., CMRR;

The slew rate is infinite, i.e., sr;

with an infinitely wide frequency band;

The offset voltage, offset current and its temperature drift are all zero;

Interference and noise are zero.

Ideal for integrated op amps.

1. Open-loop differential mode voltage gain: aod= .

2. Differential mode input resistance: rid= .

3. Output resistance: ro=0.

4. Common mode rejection ratio: aod=.

5. The input offset voltage, offset current and their zero drift are all zero.

Of course, the actual integrated op amp does not meet the above idealized specifications, but the open-loop voltage amplification of the integrated op amp is very high. The input resistance of the integrated op amp is in the order of megaohms due to the use of a differential input circuit consisting of composite tubes, etc. Due to the use of complementary symmetrical output circuits, the output resistance of the integrated operational amplifier is low, generally only a few tens of ohms.

The conditions are as follows: 1. The voltage gain of the differential lead vertical mode is infinite;

2. The resistance of the person is infinite;

3. The output resistance is zero;

4. The common-mode rejection ratio is infinite;

5. The conversion rate is infinite;

6. It has an infinitely wide frequency band;

7. The offset voltage, offset current and its temperature drift are all zero;

8. Interference and noise are zero.

The property of vp=vn is called the "imaginary short" property.

ip=in=0

This property is called the "virtual break" property. When the integrated op amp operates in a nonlinear state, its output voltage will quickly change to another constant value with the change of differential mode signal voltage, and its output voltage VO is only two possibilities

When vp > vn, vo=voh

When vpvn) or vol (vp<>

The ideal op amp is the idealization of the characteristics of the integrated op amp, that is, the ideal op amp of rid=, rod=0, aud=, etc.