Questions tagged [diff-amp]

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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 ...
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38 views

Rectified DC current measurement using shunt or Current Transformer

I am working on a project to design a controller for battery charging solution. A 3 Phase delta power (440 Vrms ph to ph) is given to a 3-phase Variac Transformer ( Variac is operated ...
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1answer
87 views

Floating Differential measurement?

Can I simply hook up an opamp inputs, (either using a differential or in-amp topology that is/are also powered from a floating power supply), across a device under test that itself has exceeding ...
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1answer
502 views

Differential amplifier exercise problem

I am preparing for an exam and I am not sure if my solution is correct for this problem: We have a differential amplifier with 2 NPN transistors (T1, T2). T1's collector is directly connected to ...
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46 views

How can I bias this Differential amp. circuit at the best operating point?

I'm looking to find a way to bias this circuit: I've written down a couple of equations for DC load line(and also DC half circuit): and these two as AC Load line: Rc is given by 1K and you can see ...
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56 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-...
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639 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 −...
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1answer
1k views

differential amplifier inaccuracy resistors exercise to calculate CMRR

The common mode gain for a differential amplifier in the general case is: $${V_o \over V_c }={ R_1R_4-R_2R_3 \over R_1(R_3 + R_4) }$$ simulate this circuit – Schematic created using CircuitLab ...
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0answers
25 views

What is the difference between galvanic skin response and skin resistance of human skin?

I know this is not related electrical directly, but op amps and Wheatstone bridges are used in these applications. I have seen, Wheatstone bridges with a differential amplifier are used in skin ...
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40 views

BJT Differential Amplifier with active load Analysis

I completed the theoretical parts of DC and AC analysis. I want to test them with the simulator. Both DC and AC analysis failed. I killed DC sources in the AC analysis section and I short-circuited ...
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55 views

Differential Amp - Bipolar transistor

I can't get the same answer as they are getting.. Here is what I'm getting: $$ Acc = \frac{V_{oc}}{v_{ic}} = \frac{-R\beta i_b}{v_{ic}} $$ $$ i_b = \frac{v_{ic}}{r_{\pi+2R_0}} $$ => $$ A_{cc} = \...
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65 views

Is this gain calculated correctly?

In this schematic, if the T5 transistor is off and the T4 is on, what would be the incremental resistances ri3 , ro3. my guess is that: ri3 is : rPi4 + RE5 + Rspeaker. and ro3 is : RE5*(B+1) + ...
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58 views

How to calculate the size for differential amp

In the baker's book (CMOS. Circuit Design, Layout, and Simulation) ,it just teach us how to calculate the gain,but it does't teach us how to calculate the size for a amp,take the differential amp for ...
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52 views

Differential transistor stage current not changing with temperature

I asked similar question recently, which also referred to differential transistor pair, but this one is different. I made this circuit (in real world): simulate this circuit – Schematic ...
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1answer
263 views

How to find collector resistor value in bjt differential amplifier

What value R2 may have in that schema? Anyway it will be loaded by pn-junction of Q5 and will have fixed voltage drop near 0.65V. What value R2 must have if the current source is used instead R1? The ...
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0answers
1k views

Differential amplifier input resistance

From this link the balanced gain and input impedance differential amplifier has such resistors: simulate this circuit – Schematic created using CircuitLab $$ R_1 = \dfrac{R_i}{R_i+R_f}R_i$$ $$ ...
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1answer
43 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 ...
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2answers
718 views

Increasing the Bandwidth of Differential Amplifier

I am working on the second stage of an operational amplifier which involve a BJT differential amplifier. I am trying to increase it's bandwidth (parts of the requirements) and was told by a TA that a ...