# Questions tagged [diff-amp]

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### Transfer function of a LM380 power amp

This is an exam question. Our professor has some generator of tests and out of the blue this beast came. We couldn't ask for the clarification, being an exam question, but from what I can see it ...
454 views

### NPN Differential Pair - Emitter Voltage Variation

My understanding of how this circuit should work is : DC: The transistor bases are at about 0V DC due to R5 and R6. Some base current flows due to the constant current bias, so there is a small (~...
29k views

### Calculate differential amplifier's input impedance

How does one calculate the input impedance of a differential amplifier? Since the input impedance of an op-amp is very high, the input impedance for V2 should be R2 + Rg. But what would be the input ...
4k views

### What's wrong with this circuit to convert 0-5V to +10/-10V

I'm trying to come up with a solution to use the analog output of a DAC to drive the X-Y axis control of a commercially available laser 'closed-loop moving magnet' driver. I found an explanation on ...
234 views

### Differential stage Av value with current sources

Why all books told that Av differential of an differential input stage in power amp is very big? Ad = Rc/re, but if there are current sources in the emitter and collector circuit they will have too ...
2k views

### Why are two stages used for an instrumentation amplifier?

When we have a two-stage instrumentation amplifier, such as the following. Why do we need the first stage of the two Operational Amplifiers? Couldn't we just input V1 and V2 into the differential ...
439 views

In this article, they are explaining the benefit of using a technique called remote ground sensing by using a single-ended sensor and a differential amplifier or an instrumentation amplifier. Below is ...
162 views

### Differential Amplifier Input Line-Level Signaling

This is the circuit I'm referring to: This stage is often used as input stage of audio amplifier. I am wondering, how can the input signal be normally amplified since there is no DC bias across the ...
864 views

### Differential Amplifier Transistor Pair

I have been dealing with these differential amplifiers for weeks now and still don't understand the basic principles of its operation and how should it be used inside an audio amplifier. I understand ...