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21 Threads found on edaboard.com: Increase Gain Ota
I have designed a biquad ota-C low pass filter, tunable from frequency from a few Hz to few KHz. However if I increase the tuning current, although the frequency increases but the dc gain decreases. Please help me to understand why this could be happening and what could be the possible solution for this. Thanks in advance.[/
Hi, I am using the classic folded cascode one stage ota for the specification: gain=70dB, phase margin=60 degree and Unit gain frequency=90M Hz. load capacitor =50p F 1. How to increase phase margin without decreasing gain, unit gain frequency and also without increasing load capacitor? (...)
I'm going to design a two stage folded cascode ota. first stage is folded cascode(nmos input pair) to provide gain second stage is common source to increase the output range compensation is cascode compensation My question is in my circuit, how to find poles and zeroes? It had a compex trasformer Eq. & I couldnt simple it. (...)
The gain * bandwidth of a opamp is constant if you increase the gain the BW /f3b will decrease .You can look into any book which deals with ota and you will understand better .
HI i am new to the analog based circuit design.. I have been designing folded cascode ota for 9-bit 200MSPS pipeline ADC in 90nm CMOS technology with the following specifications power supply =1v dc gain= 62db unity gain b/w =1.162Ghz phase margin =68.38deg But when i simulate the following ota for dc (...)
Hi All i am designing a telescopic ota with gain of 50 db and UGBW of 50 MHz. i am able to achive 50db but my UGBW is stuck at 11 Mhz , i want to increase this but it seems i cant change it i am using a telescopic Cascoded ota
decreasing the current will decrease the GBW of the ota & increase the gain , you can decrease the sizes of the transistors to decrease the gain ( gain proportional to length of the transistor) , so you decrease the GBW and the gain by that , and remember also by decreasing the sampling (...)
i have a charge scaling DAC and i want to increase its gain by several factors (x2 x4 x8 and x16), my question is how can realise this?? PS: in my application the converter is a 9bits DAC) i'm a new commer in the analog design world, can anybody help me plz thank you
For ota, to increase the gain, you need to increase the Gm of the input stage by increasing the input transistor W/L, or increasing the input transistor biasing current. and you need to increase the output impedance, since the overall gain is G=Gm*Rout, to increase Rout, (...)
maybe u should increase the gain.
There are many tricks experts here already recommended. If your GBW is not so critical,you can reduce your Vgst lower to increase the gain.
hi every body first of all let me till u from my a little experience that the gain , phase margin and the settling time or slew rate is most important parameters for any OP AMP utilizing in A/D converters, in fact is there any technique to increase the phase margin with out effect the settling time or the gain. best regards
I think a single stage ota will be easier to design... You may try folded or current-mirror topologies. Sizing: start by an initial W/L guess. This is usually done by choosing the bias voltages and sizing transistors to achieve the desired swing. Then you will go through iterations to optimize. For example: to increase gain, (...)
In fact, ota is the same Op Amp when you want to use its transconductance charateristic (output current/ input voltage), but since normal opamps have small input range that the G spec. is linear; thus you should increase input range for more linearity by various techniques e.g. gain boosting (or use further simple opamps at input). you can (...)
It's not true. ota+output buffer=OPAMP. The term ota can be applied to any of diff. stage configuration, e.g. CS with active load, telescopic, folder cascode... Their have large output resistance Rout for increase gain (A=Gm*Rout or A=(Gm*Rout)^2) and their isn't situable for drive resistive and large capacitive loads. That (...)
Hello, We want to design an ota with a gain of 8000. The first stage is a telescopic cascode and the 2nd stage is simply a CS. We tried to size our transistor but it seems like a mission impossible for us to get such a high gain. Can anybody help us? Thank you very much Just use the gain-boost to (...)
I browsed almost all the papers of the IEEE of the gain boosted ota, all mostly said about the same thing, just add a Op Amp to increase Rout, like the picture attached.... The problem is how to decide the bias and the Width/Length of the the added Op Amp. I used the Op Amp as same as the original one(the one needed gain (...)
hi everyone I have a problem in my design. when i use BTL output ,the THD is large ,i simulate with spectre now i have found the problem ,in sometime the NMOS and PMOS power thansistor both off. i think that the ota's gain is too small ,so i let the bais current increase ,in this time the THD is improved but if i do this ,the (...)
for a self biased single stage ota, the maximum gain is about 50dB. As the tail current inc, gm inc but ro dec so the gain isn't increase But u can reach a 60dB gain or higher using a folded cascode or a telescopic cascode otas
I'm going to design a two stage folded cascode ota. first stage is folded cascode(pmos input pair) to provide gain second stage is common source to increase the output range compensation is cascode compensation My question is in my circuit, how to decide the input pair IDS and folded branch IDS. Is there a design iteration flow for (...)