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Questions tagged [diff-amp]

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36 views

BJT current mirror with Early effect

I'm trying to determine the reference current for the BJT current sink to have a certain bias current value for the amplifier. I also need to consider the Early effect for the BJT. So basically I need ...
58 views

Relationship between base resistor and collector current in this unbalanced differential amplifier

For this BJT circuit, I was wondering if there was a solution for how the collector currents change with respect to the value of the single base resistor. This arrangement popped up in a circuit I ...
68 views

Comparator Undesired Behavior

The following circuit is a comparator, which compares input square signal at non-inverting pin with fixed reference voltage at inverting pin of integrated comparator circuit LM393 ($R$ is collector ...
31 views

Current source for discrete differential amplifier

I hope someone can point me to the right direction. Basically I face the same problem like the author of the following question. How do I choose the correct current for my differential amplifier? I ...
78 views

How to analysis this Operational-Amplifier circuit?

This is a reference buffer circuit that make a single-end audio input to be the differential inputs for ADC. Circuit-1: It does not like typical Op-Amp circuit of the same purpose like below. ...
78 views

Understanding negative feedback in an inverting op-amp

Below is a basic inverting op amp. I'm having trouble seeing the negative feedback operation. simulate this circuit – Schematic created using CircuitLab If I understand the "golden rules" of ...
77 views

Differential Amplifier to Scale Down DC Voltage

I'm using a 3.7V LiPo to power a device that normally runs on 3V (and draws about 100-200mA). I've determined that my device can run properly if I can achieve an output voltage that scales the input ...
79 views

Common Mode and differential Mode gain of this Cmos diff Amp inverter

This is one of questions our prof gave to students in recent years and im preparing myself for this exam. What is Common Mode and differential Mode gain of this Cmos diff Amp inverter? i understand ...
181 views

What step have I missed designing this differential amplifier?

First time posting on EE.SE and I hope this question isn't too broad. This will be a long post. I should also point out: I'm asking the process and not the solution the problem. I've did create a ...
238 views

Output voltage of MOSFET differential pair with current mirror load

I've seen this circuit from https://www.allaboutcircuits.com/technical-articles/advantages-of-the-actively-loaded-mosfet-differential-pair/ How are the drain voltages equal?? I can't seem to figure ...
240 views

Differentiator (Op amp) with a square wave

I'm working on a differentiator (op amp) with a unitary gain i calculated the value of RC and the period with a frequency of (1kHz). Figure 1. Differentiator Schematic (OrCAD). This is the schematic ...
61 views

What is a good way to add a programable offset to a diffential signal?

I have an AC coupled, ~10 MHz to 1 GHz, differential signal, with a programmable gain, coming from a detector. The signal contain pulses, and the DC-balance is poor but constant (even if my hand ...
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 ...
54 views

55 views

differential amplifier measuring current below supply rail

I am measuring the current from a battery (12v) using a shunt resistor. But if i can i want to use the normal rail as supply for the op-amp: Now my thinking is that because of the two voltage-...
1k views

High Gain Amplifier using BJT

I need some assistance on building a high gain amplifier using only BJTs, capacitors and resistors. I have made some before using op amps, but for this assignment I am not allowed to use Op Amps at ...
526 views

Single input impedance of long-tailed pair

I have following circuit: and I'd like to know input resistance of single input Ui. I tried to calculate it like this: if I increase Ui by little, there's some voltage drop on base-emitter junction (...
71 views

Differential Op Amp Output voltage

I was just wondering if someone could tell me if I am doing this right, because I don't really have any sample problems but just want to be prepared for anything. If we wanted to find the output ...
42 views

Differential Op Amp queston

So we are given the equation: Vout=Rf/Rs(V2-V1) I'm just wondering how would we solve it when the Rf/Rs are different values like they are in this circuit: simulate this circuit – Schematic ...
574 views

Sallen-Key with fully-differential output — options?

I have a single-ended audio signal that I want to low-pass filter and convert to differential (with GND as the OCM voltage — that is, when one output is X Volts, the other output shall be −...