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good day everybody.. i'm doing simulation right now about high swing cascode current source. this is about the self bias high swing cascode current source. please refer below for the figure. (i found this circuit in CMOS Analaog Design by Allen, 2nd edition page 133.) In this (...)
idea to make well matched current mrrors is simple: ids=B(Vgs-Vth)^2(1+λVds) make Vgs (it is normallly done when you connect gates and sourcea) and use matched mosfets(important matching is for mosfets near gnd) with same Vds (by proper circuit configuration and biasing). For matching L has to be high enough ...say 4-10xLmin... For high outp
Hi there, i've failed to bias wide-swing cascode current mirror properly using 1.8V supply. The circuit i used is Fig 6.11 from Ken Martin book. Is it impossible to bias 4 transistors in cascode because of 4xVdsat? I need high current so that i can reach high slew rate. Can anyone help me or give me (...)
There is another question about device sizing of the other high-swing bias circuit. What does the objective "VDS1=R*Vd1,sat" mean ? And why Vd6,sat equates Vd1,sat in advance!
Hi.. any one know any technique which can be used to design a current mirror capable of providing 10mA with low voltage headroom (less than 0.3V for the transistor to operate, the signal swing takes about 2.7V with 3V power supply) and high output impedance (more than 5k)? Is it possible cascode current mirror can achieve such a low voltage (...)
While it will increase CMRR,which is mandatory, the cascoding of the tail current source has nothing to do with the Av part of it. If you look into the differential half circuit, you will notice that the tail current source will never come into that part. Moreover,in your case, the OPamp might need a very high PSRR- as well. Hence they will hav
show the circuit for design high swing current mirror. how to design?
I find this site but thel link was deleted Can you give me a link for this book?
try this book
typical wide swing cascode is shown below. (Fig A) some wide swing cascode circuit uses pmos instead of nmos. example is shown below. (Fig B) Pmos is used as diode connected nmos. however I don't know how it works exactly. Is it Possible to use pmos is not connected drain & gate terminal ? How can you say pmos (...)
An another point of view. Small bottom MOST only is used in high frequency application. If consider low offset, noise applications and bandwidth trade-offs mirroring MOSTs must operate at strong inversion level with small value of Gm. Usually this gives small W/L ratio (high ro1). Influence of cascode MOSTs on offset and noise really (...)
Hi! Has anyone a link to a full presentation of a wide swing cascode? Or, better can someone guide me through the wide swing cascode principle? Thanks, D.
Please help me with this guys. I 'm trying to grasp about this high swing current source. Below is the diagram of the high The resulting A-wave: images.elek
how do i generate Vbn Vbp Vcascn Vcascp Vbcm??? if opamp is fully differential.... look up bias generators and high-swing cascode mirror bias this link is a good start, then you need a second branch of mirrors to bias the other
the reason is most probably due to different Vds.use a configuration that has high rout may be cascode or folded cascode
Did u try folded cascode with source degeneration. Use high swing cascode at the ouptut.This will solve ur problem for sure. 20 MHz is easily acheiveable.
send me a design example of high swing cascode with both PMOS and NMOS devices. Thanks in advance
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 current. thanks in advance :)
You can refer gray's book, the chapter discussing the high-swing cascode current mirror.
that's design. first choose the currents (approximately) in each branch then choose the W/L to give the saturation voltage you desire. Try 0.150v Vdsat for the mirrors, size M7/M8 to give the output current you need, and choose M2/M9 to set the class AB current in M7/M8 not too high. PS - you don't bias using voltage, you bias using current
The general goal is to bias the transistors which signal travels in the saturation region to work with large gain and good linearity.Better to save more swing at the same time. I just wonder the structure of the bias circuit for a OP amplifier. How to bias each transistor in a stacked configuration??[/quote
wide swing cascode mirror is good it helps in keeping same vds for both the transistors and setting higher vgs helps especially vth{threshold} mismatch in the mirror .Probably montecarlo will still be worse if transistor dimensions are not good .
the vds if M6 is set by the vgs of M5 which in turn is set by the size of M5.This is a high swing cascode. mostly used as a load in cascode opamps(folded,telescopic etc) amarnath
to mirror current exactly,the ratio of W/L of the mirrored and mirroring transistor should be exact,too;i want to ask ,for W/L=50/0.5 with finger number=10 (mirroring transistor)and W/L=10/0.5 with finger number=2 (mirrored transistor),how is the layout?if i use the technique of sharing source and drain,the parasitic cap may be d
I designed a Phase-Frequency-Detector and an Charge-Pump, as blocks of a PLL. And what parameters I should measure of this two blocks? The mismatch of Iup and Idn and the stability of the CP? And anymore? About the current mismatch, what method I should use? The method I used is to connect a dc voltage source with the CP ou
I have tried with the self biased high swing cascode current source taken from the book "CMOS Analog Circuit Design" by Phillip E. Allen, Douglas R. Holberg.
Here is your standard fully diff. folded cascode op amp. Im using 0.18um technology, 1.8V supply. Im not getting the correct open loop output. My open loop gain is way tooo low. Cant even get a gain of 1. I know that all transistors should be operating in the saturation region. How do i go about setting all transistors to be in saturation? Do i set
Hi, folks: I come up with difficulty designing the biasing circuit for folded cascode amplifier. In order to reduce Vdsat1, I have transistor ratio of M2 and M1 to be 1/2 or even more. Then the biasing circuit is hard to design. M6's source voltage is hard to match M1's drain and M3' drain. Is there any better bias circuit designed for
I think you may need self biasing using resistors but if u need high swing try the folded cascode try to check anaolg design book like razavior meyer
i suggest u use folded cascode with CS out put stage it has high swing output, high settling time, use Nmos transistors as differential input
at the end of the RF transmitter signal chain, drive amplifier amplifiers the RF signal to high voltage swing. Theoretically, the swing can be as high as 2VDD. For example, if the drive amplifier is connected to 2.5V supply through a RF choke, then the output swing can be as high as 5V. (...)
PSRR is linked to output conductance of transistors as well as matching among them. Try to increase channel length of your current mirrors and increase the area of transistors in general to improve matching. Also, actually it depends on the Vth of your transistors, 3V is high enough to accomodate cascodes. Miller compensation could also help.
It depends on the application of the designed circuitry. If you are more particular ob the issues of input-output isolation and high output impedance use a differential cascode stage. Pls specify the application type Rgds
If u have twin tub process u could isolate the cascode transistors. Anyway for PMOS u can do that. The body effect would increase the Vt of the cascoded device. I would only use isolation if it critical and i have low supply voltage. Also if you are designing high swing cascodes then the back bias observed (...)
you could use a folded cascode with gain boosting. Have a high swing folded cascode design.
swing is not related only to the output resistance but also to the load resistance An amplifier with a low output resistance can drive a small resistive load with high swing. Think of it as a voltage divider between the output resistance and the load resisatnce. The smaller the output resistance, the larger the drop is on the load (...)
of coz, thick gate oxide use specialized high voltage transistor, process design kit must provide it. the structure looks like DMOS pay more attention to isolation between transistors take care of your high voltage ESD cell
What i know is both the rail devices should see the same drain voltage for better matching. But Why is the gate of M3 tied to Drain of M5.
I am designing a 2 GSPS current steering DAC in 130 nm technology as per specification I want 50 dB of SFDR upto 666Mhz(33% of sampling frequency). Based on sfdr requirement we require 1.6 M Ω of output impedance for current sources(for 50 dB SFDR). I am using Nmos current source + cascode transistor + switch transistor + cascode switch.
Hi Majero, The main mirror M3 and M2 need to be sized according to the matching you need between your input and output current. With that size you can look at the Vdsat you get, if that is not enough you can increase the size more. Once you have sized that sufficienctly, you can size M1 and M4 as large devices so that
I just wanted to know why analog circuits with a higher swing(amplitude) less sensitive to noise in a mixed signal environment?
Hi, May i know the supply voltage ... and whats your output voltage? And use the upper Pmos current source bias or use seperate leg if you want precise bias voltage.. It depends on you... Thanks actually my qsn states that i need a high CMRR and high swing(2.2v) supply is 3.3v... so a diode connected bias
I know 2 application of bootstrap: 1.mos gate driver for switched mode power supplies which drives high side switches (MOSFET or IGBT). they are usually fabricated in special HV proccess. 2.driving high swing NMOS transistors in switched cap ckts like sigma delta modulators or pipelined A/D. what is your application? what do u mean by (...)
Dear members I have designed a LNA(inductive source degeneration) at 900MHz with a Q of 36 using negative resistance circuit. I am trying to make a variable gain LNA from here on. I have cascaded the high Q cascode LNA with a source follower buffer to provide good S22 to match 50ohms. unfortunately since the Q is directly related to the load resis
Replica-Amp Gain-enhancement technique is used for CI desing in low voltaje aplications. Its principal objective is increasing gain not counting sacrifice the output swing and the input common-mode range. Also it works effectively with resistive loads. In the next reference you will find an application about this Paper Reference P.C. Yu and H.S
hello laglead, i didnt get what u meant by decreasing L to get high gm in order to get higher Rout , i think that increasing the L will increase the Rout and if u are talking about cascode then to increase the gm u may use large L along with large W. regards, a.safwat
I want to build a current mirror to handle 200u current. for 0.5u process, how to determine the optimized width of the device? Thanks Benjamin
of course u can use nmos only. That's the case in NMOS processs. Pmos is use to get high swing
Sorry,I want know which is the output resistor of an opamp with mirror wide swing cascode. The opamp is in this figure