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Hi, V_O = V_I * R_K * 2^N / (R * dac_Value) Multiplying dac is in the feedback path, therefore the dac "divides". A dac value of 0 is like dividing by 0. It is undefided or infinite. The output will saturate. Klaus
Attached circuit shows feedback dac of CT-DSM-ADC(Continuous Time Delta Sigma ADC). What type of dac do you think this dac is, Current(Fig.4.5) or Resistive(Fig.4.3) ? I think this dac is current type same as Fig.4.5. Here I have two questions. What purpose do you think circuits inside red (...)
Inserting an additional low pass into the feedback loop will reduce the phase margin to about zero and might even cause oscillations. If you feel a need to compensate the voltage drop, there must be a forward AC path bypassing the filter. In case of doubt check the loop stability in a simulation.
The feedback pin will servo to a certain internal reference value, usually 1.23V or 0.8V for low voltage types. Wat you could do is to compare the a third of the LDO output (10 / 3 = 3.33...) to the dac output with an opamp comparator, and then send this signal to the feedback pin instead. A low noise, rail to rail opamp like the LMV321 is (...)
Hi, is the OPAMP the feedback amplifier of your buck converter? If so: Voltage across R2 is constant 2.5V. No change in voltage no change in current, independent of output voltage. The voltage across R1 should change 100V while the voltage across R3 changes 3.3V. No other voltage/current changes. --> R1/R3 = 100V/3.3V --> R3 = R1 * 3.
Currently, I have designed a second-order Sigma-delta ADC (fin = 20kHz, fs = 5MHz). In this ADC, a 2-bit flash ADC was adopted as a quantizer, and a 2-bit dac was inserted into the feedback signal path. The attached file is the system architecture and the simulated results. 113250 According to the output spectrum of th
That seems to be true, however , in case of any fault, you might consider possible faults and consider using case temperture feedback to limit the LED drive current along with PTC..
I am trying to implement a variable power supply in my circuitry built around OPAMP (LTC1637) negative feedback and NMOS (Farnell PartNo: 2114736) being a pass element. The idea is to supply the positive input (reference voltage) from a 12bit dac and then vary the output voltage apprx 10mV steps from 2.8V to 18V DC. When I started using this circu
Hello, I am working in the design of a low-pass CT Sigma-Delta ADC and I need to simulate this CT modulator with SCR feedback dac. how can I simulate this dac in Matlab/Simulink? Regards!
Take the manufacture's recommendation, like what you find in the app notes. A 2.5V reference could be used in a 10V range ADC if there is internal gain on it, or scaling of the the input, or if it's a SAR type maybe the dac is scaled relative to the feedback resistor - and all of this, just so you can use the nicer 2.5V reference instead of a crus
Hi guys, I have designed a PCB with Xilinx Virtex6 LX75 and connected some high speed dacs to this FPGA. In this board unfortunately I used bank 16 to connect one of dacs and I got a problem regarding to clocking issue while coding. A clock comes from dac to MMCC pin and an output from FPGA to dac. And there is a (...)
Hi, I have a dac with a built in feedback resistor (the AD7538) and I would like to make a PGA with it (and an op-amp of course). (unipolar-although I would be curious if you could do this with a bipolar output as well) It is a current output dac. I'm still learning a lot of this so I have some questions about how to implement the (...)
i'm working on sigma-delta adc in simulink.i need a 1-bit dac in its feedback loop. from where should i get it?? please help me someone as soon as possible... Thanks in advance
In Continuous Time Delta Sigma ADC, there are two options in feedback dac generally. (1) Current dac (2) Voltage dac or Resistive dac Regarding thermal and flicker noise, (2) have advantage. Regarding calibration for multi level dac, (1) have advantage. Regarding speed, (1) have (...)
Hi, I am given a 2 bit digital output and I have to implement an ADC and maximize the number of bits/resolution through an analog circuit.. I've been reading up on ADCs and the Delta-Sigma converter seems the most relatable one in order to solve this problem because of its dac feedback. Other than that, I am not too sure
Are you sure you want a current mode dac? Or would you be better off with a discontinuous conduction, PWM and inductor "dac"? This latter is real uC friendly if you don't particularly need feedback control of current but just a set-and-forget kind of cal-map. Any dimension can be digitally modulated; the design values at play would (...)
Hello everyone......... I am working on Sigma Delta Modulator For AUDIO Range of 0 to 20KHz..... I designed the two stage class A/AB amplifier, internal positive feedback hysteresis comparator and 1 bit dac.... My supply voltages are 0 to 1.8V in 180nm of technology in CADENCE.... But for both amplifier and comparator my PSD vs
I need help regarding a 5th Order Sigma Delta ADC design .. CLK = 384 Mega Hz ... what is the most suitable type of to implement the feedback dac ? as i already tried the most simple structure and it's not working good with this high speed CLK ... i read about 'current steering dac ' for example , is it suitable and accurate enough for (...)
Hi all,I'm designing a output buffer for dac, and intend to use a 2 stage miller compensated OP or a OP with class-AB output stage as showed in the picture(1) and (2),they are both feedback connected by 2 equal resistors to get a X2 gain,but the simulation show that when the input voltage changes from 0 to 1mV,the output node Vout changes very slow
I would like in switching power supplies controlled TopSwitchJX (flyback) replaced the error amplifier with an external reference.Suggest you consult as compensation network, gain, etc.? Basically my point of replacement TL431, operational amplifier and a fixed reference point I used the dac to control the output voltage of the source.