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Dear All, The normal regulator only converts the positive voltage and their substrate is ground. Now I want to design a regulator, whose negative input voltage may exceed its negative substrate voltage. For example, its input voltage is from -10V to +10V, I would like to convert it to constant voltage -5V to +5V. But (...)
Hi All, How would a negative input delay (set_input_delay -min 'some_number') constrain the combo logic inside of the module? Thank you!
please post your adc IC number so that we can have an idea on what you are actually talking about....
I think the testing depends on the resolution of the adc you designed. If the Spec is lower than some DAC in the market. you can buy one and design a test board by yourself. it is not necessary to have a high performance instrument.
There is always a chance of blowing a chip with to high or negative voltages applied to its inputs. Some 5V IC can withstand a couple of more volts and a small (between 0 and -1V) negative voltage, but if you use a small serial resistor (100Ω) and a 5.1V zener diode connected between adc input and GND (...)
I'm trying to get samples from output of a sensor. Output varies between 1.1V to 3.8V. My adc (it's a 16bit adc sampling at ~80Ksps ) has only positive external reference (VREF) input. I used an external tempereature compensated precision 4.096V voltage reference. Now it is sampling 0 to 4.096V . But my signal is only at 1.1 to (...)
in pipeline design for ex: Does 10 Ms/s means that the clock signal will be 10 MHz?? And what is differantial input? How can be applied a differantial signal to the input of the adc? For ex: a ramp function is applied to the positive input, than what will be applied to the negative input? (...)
Hi, I need to sample an analog AC signal ranging between -0.1V to 0.1V. I will take the digital ouput to an fpga, however Im having diffuculties in choosing the right adc, since nearly all of the ones I looked act as if they accept only positive voltages in single ended operation and choosing a negative input to V- in differential (...)
You need to calculate the resistor ratios for correct gain and care for keeping the AD8138 permissible input voltage range. VCOM is solely commanded by the required adc common mode voltage.
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.
There are well understandable reasons why a 100 MBPS adc should use differential inputs. A number of recent adc can be nevertheless used single ended with 0 - 3 V input range. A certain linearity reduction compared to fully differential input drive must be tolerated. A fully differential amplifier gives (...)
Hold the Phone.... "RF devide" you mean RC divider. this adc does not do RF..... 200 kSPS is max
hi all I've a question about amp parasitic input capacitance. In pipelined adc 1.5bit stage, in the MDAC amplification mode, feedback factor is 0.5.(neglect input parasitic capacitance). but without neglecting opamp's parasitic capacitance, feedback factor is much smaller. Now, I've a question about that. For calculate (...)
i just wana ask if there are any limitations in electric current being inputted in the adc module of the pic16f877? i am presently working on a project using the adc module and i have configured it as a 4 7-segment digit voltmeter in the mean time to test it. when i input 5v from the pic supply itself using a (...)
hi all i want 10 bit adc.The input signal for adc is 0 to 8v . here i seen AD571 it well take 0 to 10v, it is the full scale range. my signal range 8v. How to convert this 10v to 0 - 8v full scale. pleace suggest me any other 10bit adcs with 10v analog input. thank you
That is a very common issue since adcs are usually unipolar. Time ago I saw at Maxim website a simple but effective 3 Rs front-end solution which address your problem: adc input connected to a voltage divider from Vcc (2 Rs) and another R from there to your input (negative sometimes) choosing proper R values (...)
I am designing a 6-bit adc for a linear input. The linear input for my adc is coming from a temperature sensor. The temperature sensor's output is 0.3 at -40°c and 0.7 at 125°c. I have attached the architecture of this design, I take it from a journal. The problem that I am facing right now is that the (...)
Dear all : as the attachment shown, the reference voltage generator ( for Pipelined adc testing PC Board) is implemented by two resistors, two capacitors, and two unit gain buffer. My questions are as follows: 1. What's the purpose to add two 10Kohm resistors in series in the positive input node of OPamp ? since there
i use opamp to convert 4 to 20mA to 0 to 5v output before input to adc brfore,so can u suggest any opamp without negative input,o any adc direct convert from current input to voltage need of an opamp. Use a 100ohms+150 ohms as a shunt to the 4-20 mA signal and feed to PICmicro. You will get (...)
I'm trying to drive the differental input of ADS5474 with an opamp single-ended to differential converter. I used the recomended opamp configuration and i took into account the source impedance and proper terminations. but when i plug the source(a 50 ohm signal generator) to adc board, the DC balance between + and - input pins of (...)
can anyone tell me what is the meaning of the adc analog input bandwidth? i see the defination is as follows. but i do not know clearly. Analog input Bandwidth The analog input frequency for which the measured input signal power has dropped by 3 dB. Added after 3 minutes: sorry, its the definat
Hi Everybody , I have this adc code below , the ADRESH send to the pc stable and just great , while the ADRESL has lot of noises where i dont know from where i get them , can anybody help me out to sort this problem , i connected resistor and RC filer at the input of the AN1; which is not helping , i'm using 20MHZ pic18f , from where this nois
in calculating the offset error of bipolar adc,whwther we need to take the first transission at the negative input or the deviation at the code zero
i need to meas the dyanamic performance of adc what input freq i should chose to calculate the dynamic perf my sampling freq is 4msps
Generally, it's a good idea to follow the adc vendors reference design, at least if you don't have an exact understanding of the requirements. Is it necessary to use one more filter or capacitor after op-amp? May be, depending on the (unsaid) adc type. It can be required to isolate adc switching input currents from the OP (...)
... Is there any relationship between adc input voltage range and its sampling frequency? Only when the inverse of the sampling frequency gets near to the max. internal (sample, switching, output) time constant of the adc. And not to forget: for a 10bit adc, e.g., it takes about 7 time constants (ln 1024) to load a capacitor
since vref=2.5V, then all 1s should be at vp-p=2.5V. 3Vp-p maybe means the adc still can work properly at 3V, while if it exceeds 6.5V, Vgs maybe exceed its limits. That is what I guess. Hope it helps.
Use an opamp and shif the voltage from -2V/+2V to 0V/4V by adding +2V offset, then it can be easily connected to the adc0808 .. Here are details on how it can be done: Rgds, IanP :D
Guys, I need to design 12Bit 1MSps SAR adc with input having of 0~VDD range and 20KHz. input will be coming from selection MUX. Can single-ended topology cover for this spec or should go with fully differential topology? And if I pick fully differential topology, I need to single-to-differential converting for adc (...)
use a voltage divider using two resistors in the output of your dc source and use the voltage from that divider to the adc. For example with two resistors 3k (+ side of dc) and 1k (grd side ) you can get 1/4 of the input. You should probably use some king of protection for the input of the adc in case the voltage goes over (...)
Hello, I have a question about the adc in general, many of them have a very low input span voltage. Is it for reduce the preamp/buffer stages in front of them ? the input stage need to be low noise and assume that the power supply, (crosstalk effect on pcb tracks etc...) should be very clean... so is it really an advantage ?
When you are taking about micro controller u need check the max handling capability of the device... What is ur application?It seems your application is not for high speed and using 400MHz will be over design.Select the adc based on ur application and processor interface from adc...
. It depends on your sampling rate. adc is linear but your detector is not. Do you want to only track changes in Vac over long term or short term interruptions or do statistics Avearage & deviations ? Choices: quasi RMS with Peak, P-p or rectified average I would use LPF Noise filter and rectified average with another LPF. 200Hz LPF before br
Hi can anyone pls share how to sweep the DC input for a differential circuit. I used a vcvs to convert a single input to a differntial signals. However, problem arise as the negative input will not turn on the other end of the amplifier. WHat's the correct way to do it ? I need to sweep this to get the differential (...)
Searching for a 1-bit DAC schematic to use in the design of a swtiched capacitor SIGMA-DELTA adc. I know that a 1-bit DAC DAC is simply a switch that connects the negative input of the difference amplifier to a positive or a negative reference voltage. I just need a point in the right direction. Cheers for any help :)
Hello Friends, I have question about OP Amp: In the Symbol we have two input terminals of the OP AMP (called positive and negative respectively). In the schematic we have two input transistors (say NMOS), then how we can say which transistor is held at positive and negative terminal respectively. Please help me to (...)
thanks for your attention! I have sovled the problem. the amplitude of the source signal can't be 1, which equals to the Vref. that will lead to the unstable state. but is that the rule of adc? for delta sigma adc, large input will overload the quantizer. the input range is often limited.
what is the result at output pin if the input given to microcontroller is negative voltage at any input port
1.What's the meaning of " input bias current" for a comparator? What's the meaning of " input offset current" for a comparator? 2.How to simulate these two parameters? Thanks.
hi, i've connected a 12-bit adc with microcontroller. my problem is the values keeps fluctating. i tried adding 0.1uF cap at adc analog input pin, adc got stable to some limit but not fully. my analog input voltage is coming from an op-amp. The analog voltage is constant, i've checked that. Please help (...)
hi, im tryin to make the input 2 to be bidirectional in term of signal flow which is a audio signal. first: i input 1khz,1Vp sine signal in input 1 i can c a probe proper signal in input 2 and output 1. second: i input signal in input 2 while input 1 left floating. (...)
Hello: I have a audio sigma-delta adc, when input =1Vpp, dynamic range > 80dB, when input < 1mV, noise floor < -80dBV Bt wen input~10mVpp, we have 2nd, 3rd, 4ht ...harmonics about -60dBV Does anyone meet similar situation before? Thanks in advance
hi, i have designed a very simple circuit. in which a small voltage from a sensor is givcen to OPAMP--->current limiting resistor (with a zener diode)---->adc---->uC----->LCD, as shown in figure. But as i chnage the value of current limiting resistor the voltage changes on the adc input pin (i.e. across the resistor) why s it happening (...)
budhy's design is accurate if your adc's input impedance is much much higher than R2. If it isn't, then you can change the resistor values to account for the adc's input impedance, or you could add a high-impedance opamp buffer as roykyn suggested. If you are measuring high frequency, you may also need a small (...)
One of the most common input protection circuit consists of a resistor followed by 2 diodes: one connected between the adc's input and +Vcc and one connected between the adc's input and -Vdd (or 0V, if it is the lowest voltage in the circuit) .. Here is an example:
Hi All, I am new to designs. I need to use the ADS1252. The Bipolar input is +/-5V. Do I need to use +5V, -5V for the OP amp? In that case I cannot use OPA2350 since the maximum rating is 7V. Is there any other opamp for this application? I am using Vref as 2.5V, How I can give bipolor +/-5V using OPA350. Any one pls explain this circuit?
Dear all, How do I do power on reset about my voltage is 1.2V? If I simulate adc, my input is sine waveform. Is it used ideal waveform? If I want to use the capacitor 100p , how do I used 1p? If I don't used OP, how do I do? Thanks very much.
Hello, next time I will take part on some 12bit SAR adc workshop. I'm an newcomer on this adcs, I know only coarse how they works. And I want ask some interesting questions! Can somebody help me? Thanks
Hi every1, I am basically designing a battery status monitor circuit with MATLAB in which i need to monitor the voltage across the battery constantly with the help of a digital comparison circuit which compares the battery voltage with its maximum voltage at regular intervals. I am almost done with the circuit ,but i face problem in connectio
Dear all, i want to know what properties should be checked in using a particular adc or DAC in the electronic design.