Questions tagged [analog]

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

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Low noise high voltage gain amplifier

I have a very small voltage output in microvoltage range. I want to amplify it to atleast milivolt. So a voltage gain of 10^4 is required. Can anyone suggest any suitable amplifier for that?
Brishti's user avatar
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Debugging the triangle wave generation using ISL7044

I am trying to simulate an Analog PWM circuit as shown in this TI application note. Link attached here => Analog PWM TI Report However, I have a requirement to achieve the same using ISL70444 OP-...
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What is the standard procedure for analogue IC tapeout?

This is probably a very broad question and I will try to be more specific. I'm asking this question to get a sense of the gap between my knowledge and a 'successful' tapeout, as I've heard many people ...
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How can I route vias to components?

I am trying to route a capacitor to the base of a transistor but when I try to route a resistor terminal to a via, KiCad doesn't permit me to connect the resistor to the via terminal directly.
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Fly-buck converter common mode attenuation

I'm designing a "fly-buck" converter, as shown in the example picture below. For coupled inductor I was planning to use one with 1 kV functional isolation voltage. This converter needs to be ...
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NTC interfacing with ADC Do we need a LPF after NTC

I am interfacing an NTC with an ADC present in FS32K146HAT0MLLT .The circuit is given below.I was told to follow the same circuit. This is an automotive environment. I think filter is not required ...
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Help with the AD9833 dds chip [closed]

I saw that I can use a AD5441 multiplying DAC to amplify the 0.6V output of the chip but I can not find any documentation on how I can actually use it and implement it on a circuit?
zug's user avatar
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4 votes
2 answers
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For this particular Ring oscillator topology, will the circuit prefer to latch up or oscillate?

This circuit is chosen from Razavi's textbook Design of CMOS Phase-Locked loops In this circuit, where the outer inverters are weaker than the inner ones, does the circuit prefer to latch up or ...
Tong Su's user avatar
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Understanding of Capacitive Voltage Divider

This may be a stupid question, but it really confuses me. Suppose there are two capacitors connected in series like this (C0=C1=1pF, define Vx=the voltage of the intermediate node): ...
George Guo's user avatar
2 votes
3 answers
159 views

Why do we need to transmit in a cable with a digital modulation? Can't we just put high voltage for 1 and no voltage for 0? [closed]

We know that we can't transmit a square wave pulse via EM and we need to convert it to an analog signal via some modulation. But why can't we just put high voltage in the cable to represent bit 1 and ...
allexj's user avatar
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Designing FM Transmitter [closed]

I am a student and I want to learn how to practically design a FM Transmitter circuit, I have this circuit here and I would be grateful if someone could tell me how to calculate and select all the ...
copperwire's user avatar
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My First PCB - EMI Problem on Poorly Earth Grounded Test Place

A PCB design amateur here. Stumbled upon a hard problem right at my first PCB design. I have tried to comply with the layout rules of thumb for SI and EMC, but still encountered with strong EMI ...
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What are the necessary conditions to prevent latch-up problem for Oscillators?

In his chapter on oscillator design, Razavi discusses the issue of latch-up and proposes several methods to eliminate it. However, he doesn't provide explanations for these methods. Could anyone ...
Tong Su's user avatar
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Detect when at least one analog sensor (of many) is active

I'm building a digital piano. The current design is one sensor per note to measure position, 8 sensors to a mux, with many muxes. I read muxes/sensors sequentially, and I have logic that uses the ...
testing67's user avatar
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Earphone audio level quiet and microphone not working

I am trying to connect wired earphones to a SIM800 GSM modem so the user can talk over phone calls. After a successful test with a terminal block and hand-soldered connectors, a PCB was designed. The ...
Liftyee's user avatar
1 vote
2 answers
131 views

How to create an analog power source?

I'm in the process of building a signal generator using the AD9833. It requires a dedicated analog power supply, but I'm not entirely clear on how to devise such a power supply. From various resources ...
0x1a551e2's user avatar
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Negative PSRR of Two-Stage Op Amp

From page 4-9 of this lecture note https://pallen.ece.gatech.edu/Academic/ECE_6412/Spring_2004/L180-PSRR-2UP.pdf, it gives example on how to model a Two-Stage Op Amp to find the PSRR- when \$V_{Bias}\$...
Matt's user avatar
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Does pole-splitting narrow or widen the bandgap width?

Razavi gives the answer of why the compensation capacitor should not be placed between the gate and drain of M3 transistor. Below are the quotations of his question and answer: Question: Explain why, ...
Tong Su's user avatar
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8 votes
4 answers
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How to design a circuit to measure really small currents (nanoamperes for example)?

I have to design an analog circuit to measure currents in the nano ampere range as part of a course, and from what I found on Wikipedia and some documentation available online from Tektronix, it seems ...
Koustubh Jain's user avatar
1 vote
2 answers
130 views

Dimming light idea

I have this idea to dim a light. The problem is that my EBS simulation software won't allow me to see the actual result of the dimming. The only way to test it out is to physically construct the ...
Zipho Lunika's user avatar
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Using TL431/ATL431 to make UV lockout circuit for gate driver IC

I am using UCC5350 (isolated gate driver) in 3 phase bridge circuit, sadly I decided later in the project to use isolated Bipolar dc/dc converter MGJ2D241509SC (+15/-9) for gate drive supply. 15 V ...
Eng Sam's user avatar
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How is the boundary of input CM level calculated?

I will briefly state my understanding of the following equation, and then pose three questions at the end. Equation (1) (2) refers to the circuit in the first picture, Equation (3)(4)(5) refers to the ...
Tong Su's user avatar
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What is wrong with my Colpitts oscillator?

I am designing a Colpitts oscillator. I simulated the oscillator but there is no oscillation. I don't understand why. Colpitts oscillator circuit: I encountered a problem where once the component ...
help_me_learn's user avatar
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Colpitts' oscillator [closed]

Edit 1. The question got taken down so I made edits. Here is the colpitts oscillator circuit: I encountered a problem where once the component gets small enough (I want a frequency in the hundreds of ...
help_me_learn's user avatar
2 votes
3 answers
114 views

Comparator Latch Initial state

I am working on a latching current limiter circuit and as part of it I'm using multiple LM139 comparators to implement a simple SR latch. This specific comparator has an open-drain output. A latching ...
Malte's user avatar
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For a MOS transistor, why is the maximum voltage of it be \$V_{dd}-V_{ov}\$?

Razavi stated that the maximum output swing at X or Y is equal to \$V_{DD}−(V_{GS}−V_{TH})\$ as shown in the following picture, the second picture is the Fig.4.3 I don't understand why the equation ...
Tong Su's user avatar
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3 votes
4 answers
729 views

Op-amp - Converting a negative ramp to a positive ramp

I have an analog input that I need to measure. The analog input is single-ended and ranges from -10V to +10V. I want to try and measure that output with an ADC, which has a 0-3.3 V range. I want -10 V ...
Shaken_U's user avatar
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3 votes
1 answer
216 views

Why it is difficult to use two-stage op-amps at high speeds?

Razavi motivated the design of the Gain-Boosting configuration by stating that, The limited gain of the one-stage op-amps studied in Sec. 9.2 and the difficulties in using two-stage op-amps at high ...
Tong Su's user avatar
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Why does the ES8374 have 5 pins to receive input from a microphone?

I am using a ES8374 codec for an audio application. I am not able to make out how to connect my analog condenser mic (which has two pins) to the ES8374 mic pins. (Refer to pictures from the datasheet) ...
hrithik singla's user avatar
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How to figure out the schematic inside a "black box" if the only information I have is the signal equation: U(t) and I(t) [closed]

Professor gave us a problem and I can't seem to figure it out. The task seems quite simple: we have a black box that has some kind of RLC circuit inside it, one input wire and one output wire ...
hakkulinen's user avatar
2 votes
2 answers
99 views

Why does shorting the drains linearize the transconductance of the differential amplifier?

Why, by shorting the drains in Fig \$14.15\$ in this manner, will it allow the \$G_m\$ plots to add together? What will happen to the \$G_m\$ plot if we swap the shorting transistors, i.e., shorting ...
Tong Su's user avatar
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2 votes
1 answer
108 views

Is this the leakage current of a MOSFET?

I'm trying to understand the leakage current characteristics of a 130nm PDK in Cadence. I set up a testbench by grounding the gate and source terminals of a nmos FET, and setting the drain voltage to ...
George Guo's user avatar
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LTC 2448 analog input voltage range

I use an LTC2448 ADC for data acquisition, and I noticed that the ADC has a voltage range of -2.5 to 2.5 V, but some of my sensors have a 0 to 3 V or 5 V range. I am giving the ADC a Vref of 5 V, but ...
Computerhero18's user avatar
2 votes
1 answer
149 views

Why will the offset of a source-follower which is connected to the output of an opamp as a voltage buffer limit the op-amp output swing?

I am currently reading chapter 12, "The Common-mode Feedback Circuit" in Analysis and Design of Analog Integrated Circuits by Gray and Hurst. Page 815, gives the following statement for ...
Tong Su's user avatar
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2 votes
1 answer
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How to increase the output range of a current source?

I'm trying to design a current source to charge a capacitor (10pF) in the context of IC, with quite a small voltage headroom (1.5V). I started with the basic current mirror, as shown below. M3 acts ...
George Guo's user avatar
0 votes
1 answer
73 views

Power over coax circuit clarification needed

The below image is taken from DS90UB913A-CXEVM Serializer Board Schematic. T he complete schematic is on page 21. The PoC network is enclosed in an orange box. You can see that two resistors (R28,R71)...
Hari's user avatar
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1 vote
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Symmetric PCh and NCh MOSFETs for variable resistors

I'm wanting to build a variable voltage-controlled resistor. The resistor would be in series with a 200 uA AC current source and need to be controllable between 1-20 ohm. My current plan is to take ...
Mekala's user avatar
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2 votes
1 answer
130 views

Understanding current sense circuit

I'm trying to adapt a current limiter design that I found, and I'm having trouble understanding the "current sense" part of it. The current sensing is implemented using a shunt resistor, ...
Malte's user avatar
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0 votes
2 answers
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Disconnecting load circuit from reference [current mirrors]

I have started learning microelectronics design and I am currently working on my bachelor thesis. There's one thing I wanted to ask you about current mirrors and its switching. My thesis is mainly ...
tom_ger's user avatar
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4 votes
1 answer
103 views

Testing input common-mode voltage range of an op-amp

I have been trying to develop a set-up that could test the input voltage range and output swing of an op-amp. To measure the input voltage range, the output should swing within the limitations ...
Fateme's user avatar
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1 vote
1 answer
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Getting temperature dependence for a beta multiplier circuit

I am currently working on designing a beta multiplier voltage reference, and came across this paper. I am slightly confused as to how they ended up with equation (6) after taking the derivative of (5) ...
soccernismo's user avatar
6 votes
6 answers
301 views

Effect of Vbe on Ic for a BJT

I am trying to find out where I have gone wrong in my understanding of BJTs: According to the Ebers-Moll equation: $$ I_C = I_S\cdot (e^{ \frac{V_{BE}}{V_T}}-1)$$ So if VBE decreases, then IC should ...
Xavier's user avatar
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1 answer
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How do I run a frequency response analysis on a speaker cross-over circuit using Micro-Cap 12?

I've got a simple speaker cross-over network drawn in Micro-Cap 12, I'm using a resistor in series with an inductor to represent the speaker, I've got a sine source as a voltage source to the circuit. ...
Peggy Schafer's user avatar
0 votes
2 answers
83 views

D latch circuit not working

I have made the attached circuit, to make a on/off switch for a power circuit. I have made the set and reset pins high. Also shorted the Q' and D. After many trials, still stuck up with the output Q ...
Sainath's user avatar
0 votes
1 answer
40 views

A stable very low-voltage reference generator (a very low-voltage LDO design idea) [closed]

Essentially, I have a voltage which varies between 0.15 VDC to 0.25 VDC, and this feeds into a system whose output is varying because of this variation at the input side. This is summarized in the ...
Debugger_Op's user avatar
0 votes
1 answer
83 views

Noise- Analog IC Design

I have a problem for input-referred thermal noise current. Why do we need to divide In3Rout by the gain? Is there any simpler way to make me understand? Design of Analog CMOS Integrated Circuit /...
jsdklfsldn's user avatar
2 votes
0 answers
98 views

What is the point of analysis and biasing calculations when real world performance is going to be much lower in analog circuits? [closed]

I am making a 3-stage audio amplifier as a course project. The first stage is a differential amplifier, the second stage is a common-emitter amplifier, following that there is a passive filter and ...
Koustubh Jain's user avatar
0 votes
1 answer
45 views

Parallel resistor across inductor practical model - switching converter [closed]

While designing switching converter, I have included the inductor practical model as shown in the image. Since Rvar2 is small value and in the order of milli-ohm. I see it is impacting my circuit ...
battu balaji's user avatar
0 votes
0 answers
43 views

How to quantise a bipolar analog signal using an ADC with lowest amount of signal noise

I have a linear position sensor that outputs an analogue signal between -4v and +4v corresponding to the position that I want to capture using an ADC and microcontroller. It has a maximum resolution ...
Ajay Varghese's user avatar
4 votes
1 answer
217 views

What is the purpose of the op-amps connected back to back in a thermocouple signal conditioner?

I am trying to design a thermocouple signal conditioner. I came across this structure on the Analog Devices LTC2057 typical application page. Why was such a connection made instead of using a single ...
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