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Help needed in LDO design

I suggest going back to basics. Remove the feedback controller you have, and prove that the rest of the circuit will work. Assuming that all voltages in your circuit have to be within the range of ...
Fabio Barone's user avatar
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How to use the AD829 Op-Amp? (Weird "auto" output)

From the chat-room discussion, it seems this question is part of a larger project, and I would advise reviewing all aspects of your project plan with people competent with basic RF comms technology. ...
Fabio Barone's user avatar
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Modifying a TDS Module for Higher Electrical Conductivity Measurements

Your analysis looks correct. The range is determined by feedback resistor R10. R12 will have very little effect. If you want it to be less sensitive (higher conductivity) then you would reduce R10 ...
Spehro Pefhany's user avatar
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Modifying a TDS Module for Higher Electrical Conductivity Measurements

The "yello" circuit convert an "alternating" current into a DC voltage. Note that the opamps LMV324 are replaced by LMP2011 ... Here is a simulation (made with microcap v12) of ...
Antonio51's user avatar
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For a CMOS closed-loop op amp, under what condition will the output influence the saturation condition of transistors inside the amplifier?

The virtual ground assumption is a good approximation when the amplifier has high open-loop gain. The gates of M1 and M2 will have little voltage swing because of feedback action. It's no different ...
Designalog's user avatar
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1 vote

Minimize Single Balanced Mixer Insertion Loss

This type of single balanced mixer exhibits high loss (typ. 10dB or more). It doesn't matter if the LO and RF ports are swapped or not. Another overlooked problem is that terminating the IF port with ...
Raonoke's user avatar
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1 vote
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Can I connect two speakers to a mono analog input Class-D audio amplifier

The datasheet says it will work at 5V with one 4 ohm speaker, which is about the same as two 8 ohms speakers in parallel, so it should be fine. If having two speakers results in more speaker cone ...
bobflux's user avatar
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Opto-Coupler window detector with delay

One approach can be using an p-channel mosfet instead of BJT transistors. Common P-channel mosfets have higher tresholds than BJT's, so you can use a smaller sized capacitor for the treshold detection ...
Ferrybig's user avatar
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RTC super capacitor is discharging very fast

Will the discharge happen via any other paths. Subsidiary question : Why do you need RTC_RST and Q28 ? Yes, It discharge clearly your "supercapacitor" ... after each reset (10 Ohm). Even if ...
Antonio51's user avatar
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12 votes
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RTC super capacitor is discharging very fast

This explains the issue. When 5V_uC is off the RTC will be working from supercapacitor and the microcontroller is also off at that time.The clock output of the RTC will be in enabled state. You can'...
Justme's user avatar
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1 vote

Convert linear output of current mirror to exponential

The basic idea is that there are two thermally-coupled transistors Q1 and Q2. There is a reference current flowing through Q1. Q1's Vbe is then buffered by the buffer VCVS1. Then, the control voltage ...
Kuba hasn't forgotten Monica's user avatar
2 votes
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Error analysis in analog-to-digital converter (ADC) applications

May I know from where that loss equation(log2(4.13) = 2.05) came Lets try this approach. If I asked what \$log_2(256)\$ is, the answer you would get is 8. 256 is equivalent to the number of LSbs ...
Andy aka's user avatar
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Opto-Coupler window detector with delay

Maybe you could use a 16V zener diode as voltage comparator and RC for pulse duration. A 4k7 + shottky quick discharges the cap in case of short pulse so the cap will be ready soon for next pulse.
Michal Podmanický's user avatar
1 vote
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What does this NMOS/PMOS connected to Vout do in this TIA (Trans-impedance amplifier)?

I don't get what the transistor marked below, which is connected to the Vout, does? TIA design isn't my forté but the answer (as commented by G36) is stated within the article, on page 5 of that PDF: ...
SamGibson's user avatar
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1 vote
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Avoid cross talk between recording electrodes

Note: The 10M ohm resistors connecting to AGND are needed to bias the amplifiers to common mode input, but they also create a 20M ohm path between the various electrode types where roughly 100nA of ...
Fabio Barone's user avatar
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1 vote

Transimpedance amplifier oscillating at high gain setting on PCB only

I am going to guess that when installed in a breadboard, the PD is relatively far away from the ground trace (with the emphsis on "trace"). The PCB version has the PD right snug up against ...
WhatRoughBeast's user avatar
2 votes
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Transimpedance amplifier oscillating at high gain setting on PCB only

Big fat diode, high capacitance, makes a phase shift around the loop. Put a capacitor in parallel with the feedback, between output and (-) input. I'd suggest 1 nF.
John Doty's user avatar
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1 vote

Amplification for digital caliper

I suggest you make a gain-of-one buffer with a CMOS op-amp and look at the waveforms on the commercial caliper and your circuit first. Your 'scope probe will be affecting the signals significantly. ...
Spehro Pefhany's user avatar
1 vote
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How to terminate a monopole antenna

Would connecting a low impedance antenna (75 ohms or less) directly to an emitter-follower (no transmission line) with a high input impedance (600 ohms+) be a valid design approach? No, you are not ...
Andy aka's user avatar
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2 votes
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Convert linear output of current mirror to exponential

If you wish to have a linear-input to exponential-output current conversion, simply replace Q2 with a resistor. The whole point of the diode-transistor current mirror is to turn the naturally ...
tobalt's user avatar
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0 votes
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Understanding this constant power laser driver circuit

I am unsure how to calculate the gain of the first stage since the feedback network has a resistor to ground. This stage amplifies the voltage at the wiper of the potentiometer (10 kΩ) by 2. That's ...
Andy aka's user avatar
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how to calc the equivalent capacitance of this circuit

[Edit] The following condition must be met for a properly adjusted attenuator (see schematic below). $${{1\over C1}\over {1 \over C2}}={C2/C1} = R1/R2$$ Thus $$ C1 = {C2\;{R2\over R1}} = 390 \;pF \; {...
qrk's user avatar
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how to calc the equivalent capacitance of this circuit

For scg_lg node,first simplify the parallel capacitance combination involving C4 with C2 or C5 ,take equivalent of capacitor with impedance (1/2pifc)then four impedance element connected to common ...
dhuwarkesh's user avatar
2 votes

RC filter to DC 12V, 3A fan PWM

The fan draws 3 A at 12 V, that’s the equivalent of 4 Ohms. If you put a 20 kOhm resistor in series, using the voltage divider formula you will get: $$ V_{R_X} = V_{In}\cdot\frac{R_{X}}{R_{Total}} = ...
GodJihyo's user avatar
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0 votes

High-side N-MOSFET without a driver or charge pump -Still turns ON- Is there any application involved with this?

In a synchronous boost converter when vin ~ vout, there may be insufficient time to ramp inductor current down without impacting switching frequency. If that is not desired, ‘diode’ connecting the ...
JkingNH's user avatar
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2 votes

Buffered power supply with op amps?

As per homework policy, I will give only some hints. Your simulation has all the op-amps railed so it's not really "working" whatever that means in this case. Try simulating with much lower ...
Spehro Pefhany's user avatar
3 votes

Buffered power supply with op amps?

Building the circuit Here is a possible scenario for solving the professor's "riddle". To be clear, I am just analyzing what the op-amps do, but for now I am not commenting on why they do it,...
Circuit fantasist's user avatar
1 vote

Buffered power supply with op amps?

The top opamp’s non-inverting input is Ve1 higher than Vx, and this is presented at the opamp buffer output. So the R connected to it just sees Ve1 across it (Ve1+Vx on one side and Vx on the other). ...
td127's user avatar
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0 votes

High-side N-MOSFET without a driver or charge pump -Still turns ON- Is there any application involved with this?

Is there any application for below circuit which has a high-side N-MOSFET without a driver or charge pump? I use a similar circuit (yes, not exactly the same circuit) as some sort of "clamper&...
Rohat Kılıç's user avatar
2 votes

Help me understand this high voltage amplifier circuit

I'm not in the mood for a complete analysis of this, but there are some things worth mentioning in more than comments. So, this will be sort of a partial answer. There are two glaring issues I take ...
Tim Williams's user avatar
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High-side N-MOSFET without a driver or charge pump -Still turns ON- Is there any application involved with this?

I see relatively constant output voltage independent of load resistance. Indeed this circuit (red box below) is extensively used as a "diode-connected MOSFET" in analog ICs. Typically there ...
tobalt's user avatar
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1 vote

Help me understand this high voltage amplifier circuit

I think the reason for Q5 is three-fold: to bring the DC voltage lower such that Q6 is properly biased and amplifies well. Amplifiy to keep the negative feedback operation. If you want Q6, you need ...
Designalog's user avatar
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2 votes

Help me understand this high voltage amplifier circuit

Q5. It allows the op-amp rails to be independent of the output stage rails. Q5 shifts the voltage down to whatever -VCC is. If you want to use 0 V for both your op-amp negative supply and the output ...
Neil_UK's user avatar
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0 votes

High-side N-MOSFET without a driver or charge pump -Still turns ON- Is there any application involved with this?

The big advantage of MOSFETs is there ability to switch fairly large currents with low losses. When properly driven when on they model as a very small resistor. Driving a N channel device like this ...
RoyC's user avatar
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Implementing a sine wave inverter with an oscillation circuit

Ten years later: It´s all about generating a PWM pulse train, including a feedback circuit. When not using a microcontroller, you have to use an Error amplifier + comparator. You also need two ...
Tomas Larsson's user avatar
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error in cadence virtuoso while simulation no matter what the circuit is

Here are some obvious errors in the schematic. You can check and compare with this if you don't know how to fix errors above. This is just an example, not the only way to fix it. (Image taken from ...
internet's user avatar
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0 votes

Comparator Using Common Gate CMOS

I'll be referring to these: simulate this circuit – Schematic created using CircuitLab Ideal diodes D1 and D2 limit the \$I_{REF}\$ current sources' compliance voltage to a maximum of +12V, so ...
Simon Fitch's user avatar
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1 vote

Comparator Using Common Gate CMOS

This is a large-signal effect, and in general, you'll often need large-signal effects to discuss comparators (which often turn stages fully on/off, slew them significantly, etc). Assume that M0 and M1 ...
nanofarad's user avatar
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2 votes
Accepted

SGM2052 LDO Vbias pin connection

It's a NMOS LDO: Let's look at the curves. Dropout voltage (between VIN and VOUT) can be very low as the left graph shows. But the NMOS gate needs to be biased to a voltage above VOUT, which is ...
bobflux's user avatar
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2 votes

SGM2052 LDO Vbias pin connection

What I understood from the datasheet is we need to connect a separate voltage at BIAS pin. Yes. Block diagrams on p.9 clearly show that the BIAS pin is the supply voltage of the internal error ...
Rohat Kılıç's user avatar
1 vote
Accepted

Digital Potentiometer Not Responding in Custom PWM Circuit with Arduino

Thank you to everyone who took the time to provide insights and advice on my issue with the digital potentiometer in my circuit design. I'm pleased to report that I've resolved the problem—it turned ...
Sergio Piccione's user avatar
0 votes

Subthreshold Operation for Beta Multiplier Circuit

This is the equation for the drain current in subthreshold region: \$I_d = KI_0 \cdot e^{\frac{V_{GS} - V_{TH}}{\eta V_T}} \left[1 - e^{-\frac{V_{DS}}{V_T}}\right] \$ where \$I_0 = \mu C_{ox} (\eta - ...
internet's user avatar
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