What are the requirements for a differential amplifier?
However, there are times when the electronics designer is faced with the following design requirements: Given an input range of, say, -0.5V to 5.5V, the output has to swing between, say -1.25V and +2.365V. It is clear that this requires an amplifier with a certain gain and an offset different than zero.
What is the resistor ratio of a differential amplifier?
From now on, things are simple. Since we know the resistor ratios, choosing a resistor, say R3 = 10 kOhm, then R4 = 3.795 kOhm, or a standard value of 3.83 kOhm, with 1% tolerance. Also, choosing R1 = 10 kOhm, then R2 = 7.754 kOhm, or a standard value of 7.68 kOhm, with 1% tolerance.
How to find the current of an op amp?
You can see that I3 and I4 are the current into the input terminals of an ideal op-amp. So we know immediately that I3 must equal I4, must equal 0 amps. Now let’s find the current I1.
How to calculate the differential impedance of an op-amp?
1 Answer 1. Differential input impedance is the ratio between the change in voltage between V1 and V2 to the change in current. When the op-amp working, the voltages at the inverting and non-inverting inputs are driven to be the same. The differential input impedance is thus R1 + R2.
What is the second leg of a differential amplifier?
The second leg of the differential amplifier consists of a standard light dependant resistor, also known as a LDR, photoresistive sensor that changes its resistive value (hence its name) with the amount of light on its cell as their resistive value is a function of illumination.
What makes a differential amplifier a voltage subtractor?
Then differential amplifiers amplify the difference between two voltages making this type of operational amplifier circuit a Subtractor unlike a summing amplifier which adds or sums together the input voltages. This type of operational amplifier circuit is commonly known as a Differential Amplifier configuration and is shown below: