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38 Threads found on Mirror Current Op Amp
There is a indirect feedback between Vs and VY node because upper two MOS act asa current mirror and therefore Vs is strongly related to Iout that is also related to Iin via OPamp+Resistors.This circuit acts as "current Input-Voltage Output" principal so it's a simply Transimpedance amplifier/converter.If (...)
I believe the op amp sections are: 1. Differential amplifier 2. current mirror 3. H-bridge output stage The output (H-bridge) has the job of creating the proper voltage at the load. It does this by changing its internal resistance to a supply rail.
I'd use 3 constant current (current mirror) sources with current sizes 60nA, 10nA, 1nA and digitally add or subtract them: #0: 2*60+10 nA #1: 3*60-10 nA #2: 1*60-1 nA #3: 1*60 nA
hi, Its a 'current mirror' , look at this pdf for a description. E
When You designing two stage ota, the first of all You need to add a compensation network (e.g. Miller cap with nulling resistor or used a cascode compensation). Your amplifier is unbalanced - output transistor should be matched with first stage current mirror load. In addition the phase margin and GBW depends to feedback type, reference (...)
dear everyone, how to analyze this circuit Op amp? 1-op amp 2 stage with CASCODE COMPENSATION. 2-first stage : telescopic cascode. 3-next stage : class AB current mirror. tanks regard. 98600
.... And also Every technology has a Appropriate length for exact current mirroring.. for example tsmc40 has minimum length of "700nm" to mirror exact current....(i dont know for this pdk).. ... Hi there, can you explain more in details about the sentence I quote from your reply? I'm very interested. (...)
Hi, To desiogn an op-amp you must design proper biasing ciruits which is essential for the proper operation... For current mirror you have to find appropriate length which makes good mirroring of current... And it depends on which technology you are using.... Then choose somewhat bigger area for the (...)
In the present circuit CM output is only ruled my current mirror inbalance, but not influenced by Ib. You would want to add auxilary current sources to control it. Differential amplifiers with CMFB are discussed in recent analog design text books.
No, you can get gain in the linear or transition regions - just not as much, or as consistent. A high bandwidth amp may work better with the front end load mirror not-saturated - bandwidth tends to drop as DC gain goes up (an artifact primarily of the low current needed to stay in saturation). An op amp that depends (...)
If you want to sense near ground you would invert the components and use a proper current source on the emitter rather than a Rs series resistor. You would want to use one of the collectors as an output . For example on this LM358 Op amp. 77662 Here they improve the design with a current mirror (...)
I don't think that current mirrors are suitable to amplify or buffer a small photo current, if noise is critical.
I do not see why you want to constrain the L a priori, when it is the easiest way to get decent Zout in a current mirror. With high Zout your gain will depend hugely on Zload.
can anyone enlighten me what kind of op-amp I can use to set a node with a specific voltage? Like the pic below, I want node 5 to be 0.9V, and P1, P2 are current mirror, but general opamp with no feed back can not give me a satisfied voltage for node 4 and is not stable sometimes also. 62088
The current mirror concept makes it possible for the op amp to amplify the difference between two arbitrary inputs. This makes the op amp more versatile than a single transistor. The current mirror also allows the op amp to always output some (...)
hello everyone, i am persuing my final year project in the subthreshold squaring circuit. i want to simulate differential op amp and current mirror using pspice. can anyone help on it. thank you so much regards, sushant
Looking at the internal schematic of a 339 typical comparator... The first stage has a current mirror similar to an op amp. The next stage is not as complex as an op amp. The output is simply connected to the collector of an NPN transistor. The emitter goes to ground. The most significant difference from an op (...)
i am trying to design an op amp with subthreshold operation. May i know which MOS are allowed operates in subthreshold region? the input pair? the active load? what about folded cascode configuration? As far as i know, the current mirror must be in saturation to ensure accurate copying. MOS op
Yes. It's very odd. Given Vcc is 12V. Then, voltage over R800 would be around 10.5V. Also you got Ib>Ic is obvious - assuming you're talking about Q800. I'll guess you could solve this by adding a resistor in between vcc and Q850. I haven't seen a current mirror like that before.
Hi all, I have designing folded cascode OTA as shown in the schematic. I can get reasonably good gain (74dB) and f-3dB=600kHz using 130nm (1.2V) process. What bothers me was the wide swing cascode current mirror of PM12 and NM16 (the circled transistor in the schematic) is in triode region. In the schematic I also display the operating point.
Dear all, Could anyone please explain me 1) how to draw the small signal equivalent model of either CS or CG amplifier. 2)how to draw small signal equivalent model including noise sources. for the below figure 3)How to find the current mirror of an op amp if specified as ign
i m making the layout of op-amp in which there is a current sour ce... can someone tell me is there anyway exept using current mirror ckt to implement it on layout... thanks..
"nmos input why do we always use pmos input in the second stage or vice-versa" the second input mirror the current of the first stage's output in DC point. "Can't we use nmos or pmos input in both the stages." I never do it. maybe it work, but DC point setup is not easy. The input and output range may be limited. you can try and simulate it.
If the differential amp is completely balanced and no offset, the currents through T3 and T4 are the same and it is supposed that the drain voltage of T3 is equal to that of T4, which is also it's gate voltage. The gate of T5 is connected to the drain of T3 which is virtually the gate of T4 - something like a current mirror (...)
the most convential two stage op amp can do, first stage is with current mirror, and the second stage is common source with current mirror load.
the active biasing , it to use , other active device to bias ur LNA , this decice could be current mirror , current soure band gap reffernce khouly
If your VIN does not vary, a folded cascode mirror wil work fine. Just remember if you VIN changes, so will your current. You may be better off designing a bandgap, a unity gain op amp and generating a Vbg/R current source then feeding that into your current mirror. THat will make your (...)
You can sum the two output currents using a current mirror. You can see this in any elementary analog design book.
Do u mean increase the bias current? Or, u increase the bias voltage from your nmos based current mirror?
please post your doubt clearly.... so that we can help you..... I'm so sorry.. I dont know my folded cascode op amp works well because two diode connected NMOS(cascode NMOS) and PMOS(active load) may be wrong design method. I can't know the type of active current mirror in ths folded cascode op amp. It s
there is an error in your input stage connection.This is a rail-to-rail input current mirror OTA with buffer stage to drive large cap load.
For differential output opamps you need cmfb circuit to set the output common mode. For single ended opamps its set by the current mirror load. About designing opamps to get rail to rail output .... its simply not possible. The best output dynamic range you can get from an output stage is by using an (...)
i have an op-amp which is used for LDO. the Vref is about 1.16V. At that point, my op-amp's offset is ~6mV will this a problem for my LDO? How to lower the op-amp offset? my op-amp is only one stage op-amp which using high swing cascode current mirror as load (...)
Hi, i'm a Italian student on electronic engineering.With other two friend,we are making a project that it consists in a op-amp with current mirror wide-swing cascode.This project is my first project.The particularitity of thi project is that we must use the gm/id methodologieand we don't known the first pass to starting this project!!! (...)
hi, i have a few questions here please help, thanks in advance. Please check this 1 stage op-amp: 1) simulation gives differential voltage gain Av=36dB which is too far away from hand-calculation 58dB, why ? NOTE : with current mirror load, Av=gm (Ron || Rop), gm depends on Ic (≈56uA) which is gm=0.00215 ; Ron & Rop depands (...)
Hi jiachang , It is very good to use to have cascode mirror for this precise replication .even though it is a feeble difference due to diff in VDS between actual and mirrored (or finite op impedance ) it may be noteworthy in some cases. I think cascode with more stacks(>2) can multiply the op. resistance thereby bringing down the differenc
The Bandgap circuit can generate the internal PTAT current. Using current mirror architecture, this PTAT current can mirror to any value for biasing. In most of application, designers will add a external Op-amp and resistor to convert voltage to current (as the image) (...)
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 (...)