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hello Clansman There is an element known as a current to voltage convertor in any version of spice. please kindly refer to the following page to know how to use it in your simulation. You can maybe add a low pass RC network to the output to model the single pole roll-off frequency response of an I to V or rather a transimpedance op-amp! htt
I'm doing a lab for my class and it says to look for an op amp with a GBW of 2*pi*10^6 = 6.28 MHz. I suppose, you are looking for an opamp with a GBW=1 MHz equivalent to app. 6.28*10^6 rad/s. Right? (Hint: In order to avoid misunderstandings like this, the radian frequency 2*pi*f should always be expressed
An op amp?s recovery time measures how quickly it returns to a linear mode from a state of saturation. Does the op amp model in pspice include the effect of saturation recovery? Many thanks. 101452
I am trying to simulate the op-amp schematic diagram for a 741 and plot a graph of Power Supply Rejection Ratio v frequency. It is defined as 20 *log( change in dc supply voltage/ change in input offset voltage). Does anyone know how to work this out on the Cadence/ pspice simulator? Do the 2 differential input voltage sources need to be removed a
Does anyone know how to evaluate the PSRR of an op-amp practically on a simulator like pspice or Cadence? PSRR=20*log(change in supply voltage/ change in input offset voltage) How do I calculate the input offset voltage? Do the 2 differential inputs of the input stage need to be grounded to evaluate the output offset?
Try to sweep in frequency from 0 to 100kHz and obtain both gain and cut-off frequency. Cut-off frequency is no magic number. We agreed it is 3dB. You can try in Spice or you can try to sweep in frequency in hardware. I in school have a VI (in LabVIEW) which I can sweep in frequency the function generator any kind of wave. Makes things easier
I have a circuit diagram that is an active Op-amp low pass filter , but i don't know how to do the simulation of its frequency response using pspice. Can someone teach me??? Thanks Use an sin input signal and ac amplitude) and measure ouputsignal => bode plot
can I design high speed op-amp on orcad if yes plz,illustrate how to get cmos models of orcad and how to design if not which tool i can use
Can anyone suggest what model of resistor, capacitor and op-amp to use in pspice for me to simulate under military temperature range(-55degree C to 150degree C )? I need model which can vary according to temperature in pspice. Thanks.
help....how to find output voltage swing of fully differential op-amp
I've designed the attached bi-polar op amp. How do I calculate the max peak to peak output swing and max peak to peak input before distortion? Thanks
will the V+ and V- of the Op-amp influence my result? Not particularly V+ and V-, but any property of the real OP that causes a deviation of the transfer function from ideal filter.
I didn't realise the model already contained the transistor information The standard SPICE uA741 model provided by manufacturers is a hybrid model using a differential transistor input stage and behavioral modelling of most OP functions. It's a common exercise in linear integrated circuits courses to simulate a transistor level u
Hello, Currently I'm working on the LDO reg. pspice macromodel but I have some concerns about the output noise modelling. After studying some papers on Op-amp macromodels I was able to obtain fairly good match between the Output Voltage Noise Density Measurements and Simulations in 10Hz-1MHz bandwidth. (The noise source was placed in series wi
please some one tell me the logic of designing a simple op-amp circuit in pspice. where the output voltage will be the square root of input voltage
Hello, how would be the method to simulate the thermal drift in an op-amp with the SPICE macromodel? I pretend to simulate the -40 to 85 ?C behaviour of the circuit and i think the op-amp macromodel doesnt have any parameter dependant with the temperature.
i want higher frequency op-amp designs. anyone has them? thanks a lot
How comparator input overdrive and propagation delay is related ?? Hi all, are you considering an op-amp with internal compensation? if the op-amp input stage is saturated, there is no more dependance on the input signal amplitude due to slew rate limitation and compensation capacitance. If you consider an open loop or hyster
Anyone seen a circuit of to do a "dirty" but cheap RS-485 receiver with an OP-amp? Need it for a cheap quick test of balanced data lines. MrEd
There is a famous book on the subject Author is Graeme, Jerald G Title is Photodiode amplifiers: Op amp Solutions
I also found this kind compensation, the third stage output use a capacitor to the first stage negative input, and the third stage is a pmos series with two series resistors. the common terminal of resistor connect to the first stage.which kind of op amp is used to multi voltage of the positive reference voltage. who can help me about this compen
Hi, if you have simulated your circuit (e.g using spectre) and have the necessary signals in the waveform display window --> start calculator --> click at the wave button --> select a wave in the waveform window --> the waveformId will be displayed in the calculator --> than you can execute nearly every operation with this waveform (e.g subtract a
hello i am building an IC TESTER which aongst its various functions has to test for proper functioning of op amp 741.How can i test it? i am using PIC for testing of various logic ics as of now. thank you.
Because in most cases there will be no advantage in doing so. Remember that it is usually preferable to operate operational amplifiers in an inverting mode since distortion due to common-mode gain is minimised.
you can write a ideal opamp with AHDL/verilog-A in Cadence by yourself, or you can find it in a AHDL library which provided by cadence.
I agree with santhoshv78, you need a bias circuit rather than just supply a ref voltage! However, you can make it simpler by using transistor acting like active resistor by connecting Gate with Drain! The main problem on your circuit is some of the transistors are not in saturation! Check your netlist@output file and track the problem transistor
Is anybody aware of a site i can go to download a fully diff. op amp component that i can import into spice? Thanks
Try to see the book : IC Mask Design - Essential Layout technique The layout of an op-amp is reviewed in detailled with all tips and tricks ! .
I was assuming that this was the resistor from the output to the inverting input. The gain will be proportional to this resistor with the other one fixed in value. If this is a load and not a feedback resistor, the comments about output swing hold and the gain should not be affected.
Guyz, What is a low noise op-amp?
An Opamp is the wrong choice for trying to supply higher voltage for LED operation because it isn't intended to provide the current you will need. There are special purpose IC's that do exactly what you want. One of my favorites is at the URL below. Search using Google, and you will find others by other manufacturers.
Tiny Low Power Operational amplifier with Rail-to-Rail Input and Output See Also: LMC8101 - improved supply current, maximum supply voltage and output current.
This can be throught. OP amp's sometimes latchup when output is driven "over" negative supply rail.
i found there was no folded cascode op amp completely composed of bipolar ?! why? i have only seen folded cascode op amp completely composed of cmos ,or composed of cmos and bipolar, but i have never seen completely constructed by bipolar. thanks
Hi guys .. is easy to see that analog is NOT MY BREAD ... (Topology what am i thinking??) .. I need an analog circuit using an OP amp rail to rail single supply 3V i've been thinking to use a MCP601 .. i need a diferential filter with a cutt off freq of 70khz .the signal i need to filter has a DC component ( well between +3 and -3 V) so i need to
Many books existed for rail-to-rail opamp design such as "Low voltage CMOS Operational amplifiers----Theory , Design and Implementation" ----by Satoshi Sakurai and M.Ismail
Hi every one I have dsigned a circuit with lm741 but its high input noise and its low slew rate is so bad for my there an op-amp like lm741 but with lower noise and higher slew rate.note that is footprint must be same as 741. thanks
Do you worry about current consumption or input current. For CMOS OP amp input current should be 0. For bipolar input current has some value. But you can reduce this input current by some circuitry. I met some input current cancelling circuit in Burn-Brown devices. But what is your question: input current or current consumption?
hello, i need advice. i'm trying to modify the 741 op amp. i know that if i increase DC gain, then my cut-off frequency and phase margin will definately go down. is there any other way that i can do to balance the trade-off? i hav set my spec: 1. DC gain = 118dB (6dB increment) 2. cut-off frequency > 5Hz 3. phase margin > 55 degrees
At least, you can try AC analysis to check the gain phase margin. It is the basic check for a opamp.
For op-ams, we generally care about voltage gain. So whether you need an op-am with high or low output impedance depends on the loading impedance compared to the op-am's output impedance. When loading impedance is low, a buffer will be required to transfer high op-am output impedance to low.
How to do the pole-zero anylysis of Telescopic Cascade op amp as shown?
An ideal symmetric opamp surpress the common mode noise components from the bias. If the opamp is used in circuits which have to reject some big signals the common mode noises get modulated by the big signal and distort the wanted small signal. So in addition to AC small signal noise optimisation run a period noise analysis with a blocking signal.
what is minimum input voltage which LM741 op-amp can amplify when used as an amplifier I tried to find this in datasheet but there is maximum value but not the minimum.May be its given in the form of some other parameter or i am unable to understand so plz help. actually my pressure sensor MPXM2202AS can give me output proportional (...)
Hello ppl, I could use your opinion on a problem I am facing with my op-amp design. It's single stage folded cascode. Trouble is I'm not able to get the current of 25uA (am getting only 21uA) to flow in the two folded cascode branch.(spice file attached) I have changed the bias voltages and sizes but without an idea of why it's happ
There are two inputs in operational amplifier. If you apply your measured AC on "+" input of op. ampl. You can add offset voltage to "-" input. ( Of course "+" voltage applied to "-" input shifts op. amp. output "negative".) You should also take into accoout the amplifier gain. (add 1 V offset if op (...)
Hi. Yes, the opamp would work, but you might want to define a new "ground" for input signals that is slightly above the real ground to make sure the opamp's transistors remain biased. Try googling "single supply opamps".
I recently need to design RSDS circuit , and would like to know where I can get information from. And how do I get start in circuit creation. I just know RSDS a little , and just wonder RSDS reciever is created by OP-amp or differential amp. please correct me if I am worng , and love to have any suggestion from you guys. thanks
To Analog IC helper : I recently design OP-amp , and got very big issue with current mirror in OP-amp circuit. Please download the circuit ( that is attachment) , Within the white square, that is the simple current mirror to provider current for different amp (1st stage) . My problem is that I set 40u A in i1 , (...)
designing an Opamp for single or symmetrical power supply is the same. Your methodology does not change.