Inverting Amplifier (OPAMP) / Non-Inverting Operational Amplifier

In this article, we will discuss Inverting Amplifier (OPAMP) / Non-Inverting Operational Amplifier. In this configuration, the input voltage signal ( VIN ) is applied directly to the inverting ( + ) input terminal, which means that unlike our Inverting Amplifier" circuit, the output gain of the amplifier becomes "Positive" in value. I saw it in the last tutorial, which was negative in the output gain value. The result is that the output signal is in the same phase as the input signal.

Feedback control of the inverted transactional amplifier is ensured by reapplying a small portion of the output voltage signal to the inverted ( – ) input terminal via an Rε – R2 voltage divider network and again generating negative feedback. This closed loop configuration produces an inverted amplifier circuit with very good stableness, very high input impedance, Rin approaching infinity (ideal conditions) and low output impedance, as no current flows into the positive input terminal,

Inverted Operational Amplifier Configuration

Inverted Operational Amplifier Configuration

In previous Inverting Amplifier training, we said that for an ideal op-amp, the amplifier "No current flows into the input terminal" and "V1 is always equal to V2". This is because the combination of input and feedback signal ( V1) has the same potential.

In other words, the junction is a "virtual world" collection point. Due to this virtual earth node, resistors, Rε and R2 form a simple potential dividing network throughout the inverting amplifier, where the voltage gain of the circuit is determined by the R2 and Rε ratios, as shown below.

Equivalent Potential Divider Network

Equivalent Potential Divider Network

Then, using the formula to calculate the output voltage of a potential dividing network, we can calculate the closed loop voltage gain (AV) of the Non-Inverting Amplifier as follows:

Next, the closed loop voltage gain of an inverted Transactional Amplifier will be given as follows:

From the equation above, we can see that the total closed loop gain of an inverted amplifier will always be greater, but it will never be less than one (union), it is inherently positive and is determined by the ratio of Rε values.

If the value of the feedback resistance is Rε zero, the amplifier's gain will be exactly equal to one (unit). If resistance R2 is zero, the gain will be near forever, but in practice the transactional amplifiers will be limited to open-cycle differential gain (AO).

By modifying the input links as shown, we can convert an inverting operational amplifier configuration into an amplifier configuration that does not easily evolve.

Voltage Tracker (Union Earnings Buffer)

If we make the feedback resistance equal to Rε to zero (Rε = 0) and resistance R2 to infinity (R2 = ∞), the resulting circuit will have a constant gain of "1" (unity) like all values. the output voltage is fed back to the inverting inlet terminal (negative feedback). This configuration will produce a special inverted amplifier circuit called voltage tracker, also known as the "union gain buffer".

The output signal is not inverted because the input signal is connected directly to the inverted input of the riser. This results in the output voltage equal to the input voltage. Therefore, Vout = Vin. this then makes the voltage monitor circuit ideal as a constant voltage source or voltage regulator due to its input-to-output insulation properties.

The advantage of unit-gain voltage monitor configuration is that it can be used in situations where impedance matching or circuit isolation is more important than voltage or current amplification, as it maintains the input signal voltage in the output terminal. In addition, the input impedance of the voltage monitor circuit is extremely high. It is typically over 1MΩ. Because the input resistance of transactional amplifiers is equal to the product of the gain (Rin x AO). The output impedance of op-amps is much lower than an ideal op-amp condition is assumed. Therefore, it is not affected by changes in load.

Inverted Thriller Tracker

Inverted Thriller Tracker

In this inverted circuit configuration, the input impedance Rin has risen forever and the feedback impedance Rε has been reduced to zero. The output is connected directly to the negative inversion input. Therefore, feedback is 100% and Vin is exactly equal to Vout. Input voltage When the Vin is applied to the inverted input, the voltage gain of the riser is given as follows:

Since the current does not flow into the inverted entrance terminal, the input impedance is infinite (ideal conditions). Therefore, zero current will flow through the feedback loop. Thus, since no current passes through it, any resistance value can be placed in the feedback loop without affecting the properties of the circuit. Therefore, it results in zero voltage drop and zero power loss.

Since the input impedance is extremely high, the unit gain buffer (voltage tracker) can be used to provide a large power gain, as the extra power comes directly to the load through the op-amp feed rails and op-amp output. From the entrance. However, most real unit gain buffer circuits have leakage currents and parasitic capacitances, so a low-value (typically 1kΩ) resistance is required in the feedback loop to help mitigate the effects of these leakage currents, which provide stability, especially if the transactional amplifier is one.

Voltage tracking Voltage tracker or union gain buffer is a special and very useful type of amplifier circuit that is not reversed, which is widely used in electronics, especially in high-level status variable or Sallen-Key type active filters, isolated circuits.

One last thought is the closed loop voltage gain "1" or Unity of a voltage tracker circuit. The open loop voltage gain of a transactional amplifier without feedback is Infinite. Then by carefully selecting the feedback components, we can suddenly control the amount of gain generated by the inverted transactional amplifier forever.

So far, we've analyzed an inverting and inverting amplifier circuit that has only one input signal, Vin. In our next article on Operational Amplifiers, we will examine the effect of output voltage, Vout, by connecting more inputs to the riser. This will then examine another common type of operational amplifier circuit called the Aggregation Amplifier, which can be used to "add" the voltages found in their inputs.