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50 Threads found on Voltage Amplifer
Hello all, I would like to know how to calculate (hand calculation) the DC offset voltage of charge senstive amplifer using folded cascode design??
Does there any paper related to this topic? high supply voltage, cmos folded-cascade amplifer made by low voltage mosfet and high voltage mosfet both. thanks.
Hi, You should have a voltage source in your device (i.e., Vdd as a DC power source). Simply measuring the current that this source gives (let's say it is idd), you can calculate the total static power of the opamp by calculating vdd*idd.
Hi, I am using PIC18f4550 micocontroller. Right now I am using inbuilt ADC to check input voltage i.e. 0 to 5v. But now as per my application I need to scan 100V to 500V DC input voltage at ADC. How can I do ? Please suggest me. Thanks in advance.
It's not a Transimpedance Amplifier... It looks like simple Differential Pair follwoing Output Stage.. The Input of a Transimpedance Amplifier is always Current,not voltage.So, using a differential pair with CMOS transistors at the input stage is not correct..
I've been studying VHF DC-DC converters to see how to make the most efficient and smallest size of an envelop tracking power supply for an RF transmitter power amplifer. It needs to be a capacitively coupled (or transformer coupled) boost converter so the output voltage can go down to near zero volts. I'm thinking of using a lower frequency like
It is not clear what you are sweeping but if it is V18 then you are looking at the common mode response which would explain why the output is fairly flat once you reach enough voltage to turn on the input stage. Keith
Hi, I am simulating RF self-biased cascode power amplifer in Cadence under the paper below: A 2.4GHz, 0.18?m CMOS self-biased cascode power amplifier. (attached below) My problem is that the output voltage, Vout, is even smaller than input voltage, Vin. Meaning that it doesn't amply at all even attenuate input signal. Could anyone help? (...)
An LM386 amplifier has a minimum supply voltage of 4.0V. Three alkaline battery cells are 4.5V when brand new and their voltage quickly drops to 3.6V where the LM386 will not work. With a supply of 4.5V the output power at clipping into 4 ohms is 132mW which is almost nothing (headphones level). A cheap clock radio produces about 500mW. Maybe you
It doesn't seem to have any errors although I can't find a data sheet for the LM2490 to check it's drop out voltage limit. It appears you are using the +5V as ground so the supply is -5V and +7V, there is nothing wrong with that as long as the regulator holds up as the battery discharges. The only possible problem I can see is listed in the paragr
A voltage mode DCDC converter, need to know the slew rate of error amplifer, assume the compensation cap of the error amplifer is C1 and C2, the sawtooth voltage range is 2V. How to calculate the slew rate of error amplifer? thanks.
One way to do it is to use an OP-amp connected as a summing amplifier and add some offset to get the output voltage for the zero point in the middle of the ADC range.
I think you need to show how you are getting you results. If from simulation then it would use a current source and the output voltage should relate to the input current and feedback resistor. Keith
As per my understanding you are using thermo-couple for detection of temperature....Also your instrumentation amplifer circuit AD594 is uncomplete my view the output of AD594 will be analog voltage so better to give this signal to adc pin of you can do interfacing.... Good Luck
Here you have a example of a headphone amplifier that that I designed few years ago. The supply voltage was equal to 3V.
i want to design a common emitter amplifer but im facing sum problems i know vcc=15v and i require a high input voltage like 10k i need a maxium output swing so what value of Ic should be considered for that ?? half of the maxium rated current?? or the rated Ic for beta??? 62811
I assume that you'll find masses of amplifier circuits on the internet. For the principle circuits, you can refer to the below LTSpice example circuit. It has to be modified for output power (stronger output transistors, increased supply voltage) and possibly gain. For 5 mV sensitivity, you should better add a separate preamp stage. [url=
Your circuit is not a simple GaAs pHEMT instead an amplifer with its own biasing. Gate biasing is negative to Source in pHEMTs and it's provided by simple source resistance so it creates a negative GS voltage when G is grounded. I think you have forgotten to connect RF choke btween Vdd and the circuit because some circuits don't have own on-chip
Hi guys, I'm new to pipeline ADC. Now I'm confused about the residue amplifier. Based on the system function block,the Vout vs Vin for every stage, should be:Vout=2^B*(Vin-VDAC), (B is the number of bit of every stage,VDAC is the voltage from B+1 bit DAC). But in the realization of the residue amplifier using SC circuit, we often
Hi, Just a query to confirm some doubt When the input to a high frequency amplifer is written as +5dBm.... does it mean that the maximum input power it can take is 3.2mW? Also if we are to calculate the maximum input voltage... how do we convert from there.... could we simply take the resistance as 50 ohm and calculate the Vrms? Thanks
Applying the offset voltage correction signal to the variable gain amplifier it will adjust the forward gain factor of the VGA and the gain factor of the offset loop amplifier. Increasing the forward gains tends to change the cut-off frequencies. Is necessarily to analyze and tune the transfer function of the loop.
You must guarantee a common mode input voltage within allowed limits. Usually this doesn't work with a floating source. You need at least high-ohmic bias resistors at the input. Consult a datasheet of a typical monolithic instrumentation amplifier for reference.
Is "Vbias" supplied by an external voltage source ?? Or as I saw, three gates are connected between them ??
When considering voltage divider, you have to consider load as well. If your microcontroller or amplifer that requires voltage from such voltage divider you have to consider this: What is maximum ammount or error in application in question? Is there a low power consumtion requirement? Is high frequency involved and (...)
i found a Schematic on line that is a little confusing to me. is this Schematic telling me the capactents of the capactiors and is so what is the voltged. The very old circuit has a max supply voltage of plus and minus 38VDC. Capacitors connected to the supply voltages and connected to the output should have a volta
hi all: for exaplem: a differential to single output amplifer's random offset voltage is vos=Δvth1-2+(gm3/gm1)Δvth3-4. in my opinion,bec the input pair and the load pair are difference type mos,so the drift come from the (gm3/gm1).but from sansen' book said the Δvth's drift usually a few mv/C. my question is :why [
yes ,it is Video Graphics Array the only confusion is that i don't know the voltage range on the R ,G,B signal pin? somebody says they are 0-0.7v,i can not find the offical document,so i can not start my design
Hi, It depends on the type of sources driving the gauges. For instance, if the signals are ground referred current sources, you can insert small resistors in the loop and using a buffer amplifer pick up the voltage for further processing. If the signals are digital, may be you can use opto isolators to tap the signal. For ground referred volt
Your Mosfet doesn't have much voltage gain. Usually an opamp with an internal voltage gain of 200,000 is used as an error amplifier.
OTA is voltage-in and current-out, so it drives capacitive loads only as it's without a output buffer. Pass gate is a large cap PMOS or NMOS, so OTA is a good choice. However, OTA has high input and output impedance, so buffering the OTA output is commonly seen. One of the beauty to change the transconductance of OTA is to change the bias current
use AC simulation, selecting device current and then divide by input ac voltage, you can get gm. I just use this method, another method is select output ac current and differentiate it to get first order gm.
R1 for degenration , to a feed back , and make the amplifer more linear for sure this reduce the gain about Ra , RB to get a sample of ouput voltage common mode , to control the CMFB circuit i think gain is not affected by these resistors khouly
A 10 uF capacitor connected to your Op-Amp O/P may destroy the O/P stage of the Amplifier, because at power on, a capacitor is supposed to act as a voltage sink, i.e., an instantaneous short circuit will be applied to your Op-Amp O/P pin, The capacitor voltage will increase gradually as it's charging from the O/P pin. Try to Avoid this approach.
There are so called "power operational amplifiers" out there .. For example, take a look at the L272: To ensure 0-10V output voltage swing you should consider +/-12V supply .. Regards, ianP
Your cmfb will make your output node stable. In your simple CMFB, the output voltage will depend on you adjustment on the size of transistor. It may get the Vdd/2, but it needs time and patience. A better way to get a certain output common voltage, you'd better use a feedback network to amplifer the difference between your current Voc (...)
CMFB being in linear (triode) region is something not good. Your error amplifer won't be able to provide a constant gain as not in saturation, thus this will create a offset in your dc reference voltage which will finally effect your common mode dc voltage. So, try to make your CMFB always in saturation region.
I test the DC gain by doing the and .dc analysis But the result is a little different. The ac. analysis shows the DC gain is 61.7dB, about 1000 The dc. analysis shows the DC gain is 898. Why the result is different ? thanx What i see from the graph is 898 is not gain, the unit is in voltage and there might be s
To design a comparator, you need to have high gain amplifer. To achieve this, design a folded cascode + gain boost architecture. Then this amplifier have to be followed by a digital inverter buffer to determine your output logic level for input voltage comparison.
Hi, I have to design a 1.2v 0.6mw low noise amplifer with 0.18um tech. The NF about 4-5dB. Can anyone tell me which topology is most suitable for all onchip component? Many thanks
Hello everyone, I have a question here. Should I use the input voltage of a DC-DC converter (i.e., the output of a battery) as the Vdd supply for all the components in it? Like the error amplifier, comparator...... Or do I have to use an internal voltage regulator?? Please help me out! Thank you in advance! Regards, rockycheng
Guys, Need some feedback on the OTA and voltage amplifier. As we know that voltage amplifer will have low output impedance and we can say it sense input and output as voltage to voltage whereby OTA will have high output impdeance and will sense voltage to current which the gain is (...)
Only in the amplifer phase, the loop is close loop. then a feedback factor is meaning. other time , the feedback factor is no meaning due to open loop. while the loop is close, open output node of feedback capacitor, then insert a voltage souce, then derive the loop gain G(s), after this, we know the forward gain of op is A(s) , then we can ge
in the ordinary amplifier we say transconductance , which is how the collaector current change with a certain voltage so in transimpedance how the output voltage will cahnge with input current so TIA is always used as current to voltage conveter and amplifer khouly
A problem about an integrator simulation; when i simulate an integrator ,a warning is followed that missing bulk source(a reset MOS switch ) would be forwardly biased. i do not know why? integrator state: 1.a photodiode is connected to negative input terminal of operational amplifer. 2. a 2.5v referrence voltage is connected to positiv
I will design a voltage adder with amplifer, need Vo=v1+v2. The basic architecture as the image below(but use two input with 100K resistors),Rf=Rs=100K. The gain of amplifer is more than 80dB, and the bandwidth is 10KHz. But I can not get the accurate output. How to make sure that two input terminals of amplifer are (...)
I want to know if someone have any document or software to design muti-section firectional coupler? I use tunneling diode to detect RF power. Second, I had designed log amplifer to transform RF power to DC voltage. What's differents between Directional detector and log amplier? I mean they both can transform RF to DC. Thanks. ps. I'm
The source at 2.5V sets the input common mode to that voltage. Depending on your technology, you have to verify that this value is within the valid common mode range of your amplifer. Your supposition when Vcc=3.3V is correct. You use AC 1 so that the output signal you get is the amplifier's gain. But you can use whichever value you want, provid
How about precise of you meter. If you test voltage ranger beyond 256 grade,you should use two or three channel amplifer to generate 2/3 gain voltage,then input to ad0832
Do you need CA to measure capacitor or charge? Charge amplifers are used in micromechanical sensors. But charge is changed there because capacitor changes. And if the speed of capacitor deviation is low, it is better to use capacitor to voltage convertors.
I'm looking for a Pulse Generator or Power amplifer schematic that can supply a square pulse (rise and fall times < 10ns, 100ns to 500ns duration) with a frequency of 100 to 1000 Hz. It needs to supply at least 500mA and have a maximum voltage of 100 volts. I have some old test equipment that can generate the wave shape but can not deliver the p