Questions tagged [analog]

Analog circuits have a range of voltages, rather than just two as in digital logic.

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Modes of operation of P-JFET

I have the conditions of the operation of the N-JFET But I can't understand how we can find the expressions for the P-JFET.Are they opposite?Help appreciated
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66 views

Have I obtained the correct simplified transfer function for this RLC circuit?

Have I obtained the correct simplified transfer function for this RLC circuit? I am trying to obtain the transfer function for the following RCL circuit. However, the response of the TF that I obtain ...
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47 views

JFET question about operation

I have a question about the N-JFET.Assume it operates at the linear region and it acts like a voltage controlled resistor. Can we say that if Vdg(drain-gate voltage) is increased then the resistance ...
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1answer
66 views

Pole at infinity and zero at finite frequency

Is there any circuit that has a pole at an infinite frequency and zero at some finite frequency? A first-order RC Low pass filter has a finite pole and zero at infinity and it makes sense, I am just ...
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25 views

IV characteristics of NMOS transitor

I have used the model of the GPDK90 transitor in Cadence. I have few questions regarding the IV characteristics: Why does the threshold voltage change with change with Vds (Vds= 0, 1.25, 2.5, 3.75 ...
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66 views

Opamp Compensation For Input Capacitance

I am going through the datasheet of LM7171 for one of my applications. Please see the below circuit. May I know how they arrived at the equation for CF? Is this equation is valid for non-inverting ...
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130 views

Which is the input resistance of the second amplifier?

If a apply a positive Vs, then D2 is blocked and D1 is working, right? How do I calculate Vo then? I know the formula is: - (input resistance / negative feedback resistor) * Vs, but I don't know which ...
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1answer
34 views

Why am I getting “Grammatical Error” in LTspice?

Why am I getting "Grammatical Error" in LTspice the instant that my transfer function denominator goes from a 2nd order to a 3rd order system? See below. Please note that the transfer ...
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1answer
38 views

ADC 1/2LSB vs 1LSB

I was going through the below question. ADC first transition at 1/2 LSB - is that not a non-linearity? I did not understand why they took the first transition point as 1/2LSB.if so then may I know the ...
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62 views

Analog Oscilloscope Flickering Signal Problem

I am using BK Precision 2125C Dual Trace Oscilloscope (30 MHz), which is analog. I'm trying to observe signal generated by the output of microprocessor. I'm seeing flickering signal (quickly moves ...
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27 views

Hall effect output to a level voltage or other useful output

I am trying to take the output of a Hall effect sensor (latching or non) that is sensing magnets on a wheel and turn it into a level DC voltage that varies with the speed of the wheel. The only ...
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1answer
40 views

Observation of negative voltage at the output of the op-amp

I am using ADA4898 op-amp. Without connecting any elements to the circuit at the output of the IC, I see a negative voltage. Is my IC broken? simulate this circuit – Schematic created using ...
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78 views

Analog switches able to send bi directional digital information?

I'm trying to send digital signals from an ST-Link V2 programmer connected to my computer to a blue pill STM32 microcontroller, but I want it to go through a DG412 Quad SPST CMOS Analog Switch. As far ...
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586 views

Op-amp homework question using potentiometer with my attempt at solving it

I nearly understood that when Rpot is 0, Vo is highest and when Rpot is 0, Vo is lowest. So I tried KCL to get Vo when Rpot is 0 (0 turns). I couldn't get Vo but just 0 volts. What mistake did I make?...
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36 views

simple MOSFET analog multiplexer

In my project, the 4051 switches two signal sources routed to the 4024 counter - an external clock signal and a manual advance clock (tactile switch). I thought that the use of the 4051 was overkill, ...
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44 views

Playback volume from old Sony voice micro cassette recorder is very low

I have an old Sony V.O.R M-529V microcassette recorder. It was found in a box packed away years ago. I put in some fresh batteries and tried to play some old micro cassettes I had, but the play back ...
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2answers
141 views

BJT in saturation mode equations

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab The BJT transistor is in saturation mode.Which are the equations which help us find the different ...
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1answer
52 views

How can I carry DC component to negative side?

I made a sine wave with stm32f407VG DAC periphal. But my sine wave has DC component 1.32V. I designed high pass filter but DC component was gone. But I don't want it to be gone. How can I carry it to ...
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2answers
59 views

Designing a common base amplifier to meet given specifications

I designed the circuit as below and I know that common base amplifier should have a unity current gain(usually <1) but I'm getting a very high gain. What might be the reason for this, is something ...
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1answer
108 views

What are the final steps to arrive at the transfer function for this RCL circuit?

What are the final steps to arrive at the transfer function for this RCL circuit? I am attempting to arrive at this transfer function $$\dfrac{V_o(s)}{V_i(s)}=\dfrac{sL}{CL(R_1+R_2)s^2+(R_1R_2C+L)s+...
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20 views

Frequency plot with a node as reference in Proteus

I'm trying to make a frequency plot in Proteus of an inverse adder amplifier. This is the schematic: The thing is that when I use the frequency plot properties editor to change the property "...
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1answer
72 views

BJT operation notes

Hello today we had a class in electronics and we discussed the BJT operation.Here are my notes: Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab Ie = (Vb-...
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1answer
53 views

Constant Gain-Bandwidth product in amplifiers

Can somebody explain to me how the gain-bandwidth product is constant in an amplifier or op-amp? I want to know the mathematical expression behind it if possible. As said here: https://en.wikipedia....
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55 views

Design a Cascode amplifier using suitable topology to meet the specifications( by Varying W/L ratio) . VDD is 3.3V

CONDITIONS Output swing has to be at-least 80% of VDD (> 2.64 in this case) . Power supply rails available are VDD and ground only. Only one current source can be used in the design IREF = 50μA. ...
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67 views

Level shifting a 0-5V signal to 0-16V

I have a Atmel microcontroller with 0-5V DAC output and I want to shift it to 0-16V (16V max. normal between 11-16V). It need an output signal with max. ~1mA, short protection and reverse polarity ...
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68 views

Analog signal level shifting and opamp selection advice

I wanted to read out and output 5-ish volt analog signals from a 3.3v mcu. So basically the signal (roughly 0.25v to 4.5v) first has to be level shifted "down", processed and then level ...
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120 views

What have I done wrong in determining the transfer function for this RCL circuit

What have I done wrong in determining the transfer function for this RCL circuit? (1) $$\dfrac{Eo(s)}{Ei(s)}=\dfrac{s^2R_2CL+sL}{s^2CL(R_1+R_2)+s(R_1R_2C+L)+R_1} $$ Regardless, of how many times that ...
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101 views

Adding harmonics to the square wave means

I have generated two imperfect square waves by: Adding fundamental frequency with 10 odd harmonics. Adding fundamental with 20 odd harmonics. What difference should I observe between two imperfect ...
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4answers
55 views

Single pole triple throw analog passthrough

I have a circuit that will simulate a device. The device in question normally communicates by adding/removing resistance from a generated signal, the source of the signal will then measure the voltage ...
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41 views

Schmitt trigger based NAND gate

If someone can help me to understand how to calculate the hysteresis of the Schmitt trigger-based NAND gate? Which MOSFET's dimension decides the Vth_H and Vth_L? Thanks.
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3answers
108 views

Working principle of inductors

Assume we have this circuit: simulate this circuit – Schematic created using CircuitLab At t=0s we decide to close the switch, then current will start flowing through the circuit and around the ...
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1answer
81 views

LTspice simulation with capacitors

I have this circuit simulated in LTspice : simulate this circuit – Schematic created using CircuitLab Here is the graph: Why does the current flowing through R2 do that thing in the beginning (...
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1answer
76 views

Capacitor voltage equation (partially charged initial state)

Assuming we have a RC circuit: simulate this circuit – Schematic created using CircuitLab We don't know the voltage of the capacitor but we know its voltage isn't greater than the battery ...
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1answer
63 views

Have I obtained the correct transfer functions for the following RCL circuit?

Have I obtained the correct transfer functions for the following RCL circuit? Please note that my Maths is a little rusty! $$\dfrac{Eo(s)}{Ei(s)}=\dfrac{1}{(R_1C_1L_1)s^2+(R_1R_2C_1)s+R_1} \tag{1}$$ ...
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67 views

Named or Standard Circuits

BJT amplifiers have a few standard configurations, i.e. Class A, B, A/B. Likewise there are a variety of standard OP-Amp circuits such as summing circuits and filters. Is there a publicly available ...
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61 views

4-20 mA sensor output to STM32 ADC input

I have a industrial sensor with 4-20mA output and I want to read that output from Stm32 ADC pin but I need suggestions to do that work in a nice way. Can you guys suggest me the best way to do it? It ...
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3answers
60 views

Calculate diode voltage drop

I have studied the diode model which treats diode like elements with constant voltage drop and depending on the bias of the diode the voltage drop varies. Now I'm starting to learn about the correct ...
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2answers
127 views

Backward diodes VI curve

I am searching for the IV curve of a backward diode but couldn't find anything, any help?
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1answer
81 views

What should the transfer function be for this RCL circuit?

What should the transfer function be for the RCL circuit? When I derive the TF (using complex impedance method) for Output voltage/Input voltage I get the following: $$\dfrac{Eo(s)}{Ei(s)}=\dfrac{1}{...
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3answers
157 views

TL082 Voltage Follower

I just made a simple voltage follower using TL082. I applied 2.5V to voltage divider 100k and 25k, and apply that 500mV to positive input of TL082. But the output of follower is around supply voltage. ...
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4answers
136 views

Design of electronic lock

I am designing a electronic lock using a electromagnet(coil).This is my circuit: simulate this circuit – Schematic created using CircuitLab When the switch is closed it will short the circuit ...
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0answers
43 views

DC Block after the Balance - what problems would that cause?

I am building a radio receiver using the MAX2021 down converter. And I am building a down-conversion circuit similar to the reference design provided by the data sheet: My problem is that I only have ...
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2answers
47 views

Volume Control - Logarithmic Potentiometer Placement

Thanks in advance! I am building an headphone amplifier with PCM1794A, OPA1612, and OPA1622. Where would be the best placement of the logarithmic potentiometer for volume control without decreasing ...
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71 views

Difference between simulator and my analysis

I have this circuit: I have done circuit analysis and found the total current to be 21mA. Here is what I have done: But when I run the same circuit in multisim it shows me 20.6mA.What could it be?Am ...
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3answers
116 views

BJT Common Emitter Output Resistance

Hello, I am attempting to determine the small signal output resistance \$R_o = v_x / i_x\$ of the Darlington pair common emitter's small signal model. I have written the equation KCL at node c, \$ i_x ...
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3answers
95 views

Convert square pulse with 24-volt amplitude to square 5-volt amplitude

Can anyone help me to make a circuit to Convert square pulse with 24-volt amplitude and has an variable offset voltage to square 5-volt amplitude and offset = 0 ? I need to take a 24-volt amplitude ...
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Balanced slope detector load impedance

Hello question about FM demodulation here:In a balanced slope detector in class we discussed this picture: How can we connect a load to the output of the Balanced Slope Detector such that it doesn't ...
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66 views

Mixed Multiplexer channels [closed]

I have a very unusual problem that i cannot even think what is causing it. I have a circuit to read the resistance of a resistor. It produces a square pulse, that is analogous to the resistance. This ...
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1answer
42 views

What is the equivalent capacitive load seen by the IC if in a datasheet of a chip CLmax=10nF given and I connect an RC filter as a load?

I have a stupid question where in the quick, the answer does not come into my mind. If in a datasheet of an integrated circuit, a maximum load capacitance is given, e.g. 10nF, and I want to connect an ...
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1answer
25 views

Choosing the shunt resistor value and capacitor for op-amp integrator based on input resistance and DC gain

I think it's option C based on C = 1/R and the R2 as 10 times R1 but apparently the answer is option A. Please tell me where i'm going wrong. The full question reads The following figure shows opamp-...

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