Complementary metal–oxide–semiconductor (CMOS, pronounced "see-moss"), also known as complementary-symmetry metal–oxide–semiconductor (COS-MOS), is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips (including CMOS BIOS), and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors (CMOS sensors), data converters, RF circuits (RF CMOS), and highly integrated transceivers for many types of communication.
Mohamed M. Atalla and Dawon Kahng invented the MOSFET at Bell Labs in 1959, and then demonstrated the PMOS (p-type MOS) and NMOS (n-type MOS) fabrication processes in 1960. These processes were later combined and adapted into the complementary MOS (CMOS) process by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963. RCA commercialized the technology with the trademark "COS-MOS" in the late 1960s, forcing other manufacturers to find another name, leading to "CMOS" becoming the standard name for the technology by the early 1970s. CMOS eventually overtook NMOS as the dominant MOSFET fabrication process for very large-scale integration (VLSI) chips in the 1980s, while also replacing earlier transistor–transistor logic (TTL) technology. CMOS has since remained the standard fabrication process for MOSFET semiconductor devices in VLSI chips. As of 2011, 99% of IC chips, including most digital, analog and mixed-signal ICs, are fabricated using CMOS technology.Two important characteristics of CMOS devices are high noise immunity and low static power consumption.
Since one transistor of the MOSFET pair is always off, the series combination draws significant power only momentarily during switching between on and off states. Consequently, CMOS devices do not produce as much waste heat as other forms of logic, like NMOS logic or transistor–transistor logic (TTL), which normally have some standing current even when not changing state. These characteristics allow CMOS to integrate a high density of logic functions on a chip. It was primarily for this reason that CMOS became the most widely used technology to be implemented in VLSI chips.
The phrase "metal–oxide–semiconductor" is a reference to the physical structure of MOS field-effect transistors, having a metal gate electrode placed on top of an oxide insulator, which in turn is on top of a semiconductor material. Aluminium was once used but now the material is polysilicon. Other metal gates have made a comeback with the advent of high-κ dielectric materials in the CMOS process, as announced by IBM and Intel for the 45 nanometer node and smaller sizes.
From page 4-9 of this lecture note https://pallen.ece.gatech.edu/Academic/ECE_6412/Spring_2004/L180-PSRR-2UP.pdf, it gives example on how to model a Two-Stage Op Amp to find the PSRR- when VBias is connecting to ground as oppose to when VBias is connecting to Vss. One thing I don't understand is...
Full problem:
I don't normally think about circuits like these in terms of energy (Joules) so I was very much confused.
What I did was find where the simplified expressions intercepts with each other to get the voltage. I scanned in my work although this text is a walk through of what I did...
As attached below, I have drawn the step down and up diagram. However comparing to the answer, it seems to be way too off. Any idea why?
Answer:
Is there something wrong with my step down/step up circuit?
Hi all :)
So I constructed this based on a video tutorial, p, and n MOS, and was wondering if it was correct before I combine them. Also, it looks very different from what the proposed answer is.
Since the equation is z=ab,
The pull-down diagram looks like this:
and the pull-up is z= a'+b'...
Inside a CPU, when applying voltage to the gates of the CMOS transistor(high input), are the gate ore another components of a transistor will generate thermal radiation which will be absorbed by the neighboring transistor?
I made a table using excel as:
D is output. Like this I get Output frequency is same as input frequency. But I'm not sure if this is correct.
PS: I'm aware I'm posting many questions, but I got interview exams coming up in August. Companies are going to come to university for recruitment and...
I use the voltage divider rule as output voltage = Voltage across R1 = 5 * ( 0.5 / (0.5 + 20) )
This comes as 0.122 V
I'm not sure why they've mentioned I leakage and does 0-state have any impact on answer.
Hi,
I was reading about CMOS BIOS which was once used in computers to store BIOS settings is a CMOS RAM using a battery backup.
This article, https://www.makeuseof.com/tag/why-does-my-motherboard-have-a-battery/, says, "If the battery fails on an older computer that stores its BIOS settings...
Homework Statement
Calculate the ration of ##w_p/w_n## if n and p transistors in CMOS inverter necessary for the least delay time ##t_p## if the circuit is used in a chain of circuits.
a) What is ##w_p## in that circuit if you're given :
b) Calculate the maximum short circuit current if...
Hey :)
I am currently doing a project on university in cooperation with CERN where I have to find new business fields for light sensitive sensors (CMOS) which every camera contains. The special feature is the radiation hardness. So you can use it for example for detecting x-rays or you can use...
Hello all,
I want to know a suitable way to calculate VTL and VTH of a gate having the gate schematic and constituent transistors SPICE model (NMOS/PMOS models). Is there an easier than doing hand calculations ?
I am now trying to design a photonic integrated circuit which will be used to replace the global interconnect layer of a LSI. I need to somehow take the output of a photodiode w/o TIA (10G signal perhaps) and then transmit that signal to other layer of the LSI by TSV or something. Assume a...
Homework Statement
This question has several parts, and I'm confused about some of them.
Consider ##Z = \overline{(A + B \bar{C})D + E \bar{F}}##. Assume primary and inverted inputs are available.
A) Implement the function in conventional CMOS logic style such that only 4 transistors are...
Hello engineers! :)I have a question bothering me i quite can't figure out.
I have a Priority encoder:
http://www.digikey.com/product-search/en?vendor=0&keywords=ls148d&stock=1
datasheet:
http://www.ti.com/lit/ds/symlink/sn74ls148.pdfAnd this RF-Switch...
I need to somehow take the output of a CMOS IC and transmit that signal over a 50 Ohm Microstrip line.
The output impedance of the CMOS IC is about 15 megaohms. I see a lot of examples for going from 75 ohms to 50 ohms or similar but nothing on something of this magnitude. Any ideas?
CMOS...
Homework Statement
1)Determine the min acceptable values for VIH and VOH using VCC = 4.5 V and output current of 20 µA.
2)Determine the maximum acceptable values for VOL and VIL under the same test conditions.
3)Compute the noise margins.
Homework Equations
i=v/R
The Attempt at a Solution...
Hi
I've been searching for a CMOS or CCD sensor with raw analog output and external reset/transfer control but has not been able to find this. Doesn't have to be great resolution.
Anyone knows if there is a sensor like this on the market today?
Best
Johan
Homework Statement
Q. I was given a equation for PMOS and NMOS drain current in triode region but I am having some confusion regarding equation please do help.
I think drain to source current in PMOS should be negative but in equation value will come out to be positive if I keep V(gs)
,V(ds)...
I am simulating cmos inverter in CADENCE
I am getting a sharp spike when output is going from low to high
and spike became more amplified like when i made rise time and fall time of input rectangular pulse signal very low . . .can somebody explain why this happening ?
when designer design new circuit, they think what's the requirement
step I
1)power dissipation should be less
2)raise time and fall time should be less
3)propagation delay time should be less
4)size should be small as possible
step II
1) how can we reduce power dissipation in cmos...
Hi guys,
Recently I had to design a SPDT switch for a project, which I was able to design using the trivial circuit with 2 transmission gates and 1 MOS inverter, like this: http://www.semicon.toshiba.co.jp/eng/product/new_products/logic/1326183_37648.html
I think that this circuit is not...
I have been experimenting with PWM circuits and I came across this CMOS comparator that seems to work well with the sawtooth generator I am using. I feed a sawtooth wave to the gate of the PMOS M3 transistor and the reference voltage I am comparing to Vin the PMOS M4.
I noticed that the...
Homework Statement
uploaded
Homework Equations
uploaded
The Attempt at a Solution
I have Jsim installed and working and have the circuit correctly done. I however don't understand how the coding works in Jsim. I essentially need the equivalent circuit in Jsim code. I need help...
When calculating delay, like the fall time delay of the output, through an inverter with rc model of the transistors (assuming Cmos inverter) why do we neglect the short circuit current through the device and what are the assumptions.
Can anyone explain this?
In the attached photo, I found M2 to be triode region b/c the drain and drain source voltage is 0 which will always be less than the output voltage.
However, I am have troubles finding M1's region of operation, VDS >= VGS - VTH.
Vout - Vbias >= Vdd - Vbias - VTH **Vbias = 0.8 V...
Hi all, I have gave this question a lot of thought but can't seem to get anywhere. Any help will be much appreciated.
Homework Statement
For a digital logic inverter for which k'n = 120 uA/V^2, k'p = 60 uA/V^2, Vtn = |Vtp| = .7V, VDD = 3V, Ln = Lp = .8 um, Wn = 1.2 um and Wp = 2.4 um...
Hi all. I don't know if I have given this enough thought but I will ask anyway. I know that a CMOS is an inverter, so for input High you will get output Low, and for input Low you will get output High. I am trying to find this out mathematically (or even just logically) but I can't seem to do...
I understand how to draw a CMOS circuit but I am not so confident if I do it right.
I need someone to check if I draw them right.
As for the second one which is a XOR gate, I am not sure at all on how to draw it since there are both the 0 and 1 inputs in the circuit.
Homework Statement
We just did an experiment on the input and output characteristics of TTL and CMOS NAND gates. We recorded the following data for each of the two gates.
1) Input Threshold Voltage
2) Input Current(for input logic 1 and 0)
3) Output Voltage(for output logic 1 and 0)
4)...
I'm a bit of a noob on all of this, but can anyone help me (or point to a great reference resource) on pro's and con's of each in designing a power management circuit?
Specifically, I'm looking for what kinds of voltage and frequency applications each manufacturing process is used nowadays...
Homework Statement
I saw this image in the internet. I want to learn how to recognize the gate, source and drain for NMOS and PMOS.
The Attempt at a Solution
I don't know if I am correct or not.
M8 ( with an arrow coming out ) is NMOS. M7B (with an arrow going in) is a PMOS...
Homework Statement
I drew a NAND in the picture.
The Attempt at a Solution
I know when A and B are both high ( value 1), resistance will be Rn + Rn because those 2 NMOS will be turned on and resistance will added up since they are in series.
Also when A and B are both...
Homework Statement
It given the expression . how to construct the complex CMOS gate by looking at the expression.
Homework Equations
The Attempt at a Solution
This solution is given as well.
I don't understand how he construct it. I know NAND is fromed by two PMOS in...
Hello. One of my friends told me that the logic function for (A.or.B).and.(C.or.D) is
From a book, I know the P1, P2 , N1, N2 form a NAND. The same for P3, P4, N3, N4.
And P5, P6, N5, N6 form a NOR.
My question is, is this circuit the same as (A.or.B).and.(C.or.D) ?
Thank you
Homework Statement
The following question:
when Vw is VDD=2.5V, what are the output voltages for VX,VY and VZ
Homework Equations
N/AThe Attempt at a Solution
this is what i though since the p-mos is ON, VX=VW-|Vtp|
now the voltage at VY=VX-Vtn
=VW-|Vtp|-Vtn
and the answer is wrong, can some...
Hi. I receive an error message once simulating in PSPICE. I have attached a file that explains the problem in details. Will be glad to know the source of the problem.
Thanks! :redface:
Hello,
I have a question about how to analyze the CMOS inverter (this circuit: http://www.cs.umass.edu/~weems/CmpSci635A/Lecture2/image10.gif [Broken]). Just to clarify, the input voltage is connected to both gates, and the PMOS on top has its source connected to Vdd. The NMOS on the bottom...
I am designing cmos logic xor gate and 2:1 multiplexer.
In my design i am using 8 pmos and 8 nmos for 2:1 mux and 6 pmos and 6 nmos for xor gate.
I am using pmos and nmos to implement complement A, means that i am not using complement directly into the circuit.
So , i want to know that is it...
Hello,
I am hoping someone can give me a little bit of help.
I have been simulating a CMOS inverter circuit. When I add in a pulse source at the input, and simulate it, I get an output which has a bit of a spikle on the transition.
I am hoping someone can help my understand why this is...
Heres an interview question which I am having trouble with:
Consider a CMOS inverter. Replace the NMOS in it with a PMOS. How would the VTC curve look like?
I was told that one PMOS would always be in saturation.
Since the source voltage of the lower PMOS is tied to Vout, how can we...
Can a CMOS sensor be used as a Geiger counter
To help the folks in Japan protect themselves from contaminated food and to get some assurance of the safety of their homes, we are putting together a team to evaluate the feasibility of writing an iPhone/Android application that would use the CMOS...
Hi, new to these forums and glad I found them!
I am working on a project that requires conversion of fairly hi-speed signals (10us pulses) from 5V to 12V. The usual open collector with a pull up is much too slow getting from 0 to 12V. I really need the ramp to happen between .05us to 1us...
I'm looking for a small camera to use in my rocket. It's about a 7' rocket, 4" diameter and 3" long viewing window. I've heard that the choices are either cmos or ccd but I don't know the difference between the two. I'm only looking to spend up to $100 (really looking in the $50 range). Any...