Ltspice simulation of a nor static logic gate with 3 parallel nmos and 3 series pmos. Jan 10, 2017 this video shows cmos transistor logic gates nand, and, nor, and or and shows how to use spice programs to analyze the circuits. Basic cmos gates three input nor gate the nor gate was implemented using a cd4007. The other important ic gate type is the sum modulo two, or exclusiveor xor gate, which has a high output only when an odd number of its inputs are high. Ive written the code and run it via orcad pspice ad. This table shows that the output of an xor gate with input x 1 and x 2 is given by x 1. Starting a new project in pspice by following these simple steps. Secondly, the input voltage to a gate has only to reach the threshold voltage level before the device begins to change state. Ece2274 nand logic gate, nor logic gate, and cmos inverter s. Ive to simulate a cmos nand logic gate using spice. Cd4001b, cd4002b, and cd4025b nor gates provide the system designer with direct implementation of the nor function and supplement the existing family of cmos gates.
Basically the exclusive nor gate is a combination of the exclusiveor gate and the not gate but has a truth table similar to the standard nor gate in that it has an output that is normally at logic level 1 and goes low to logic level 0 when any of its inputs are at logic level 1 however, an output 1 is only obtained if both of its inputs are at the same. Logic nor gate tutorial the logic nor gate gate is a combination of the digital logic or gate and an inverter or not gate connected together in series the inclusive nor notor gate has an output that is normally at logic level 1 and only goes low to logic level 0 when any of its inputs are at logic level 1. For a first best guess on power losses and junction temperatures good results can be achieved. Download woxy checkerstudy of the switching characteristics of cmos inverter and find out noise margins.
The xor circuit with 2 inputs is designed by using and, or and not gates is shown above. Now we will look at the operation of nor gates and nand gates as universal gates nand gate as universal gate. As v a and v b both are low, both the pmos will be on and both the nmos will be off. The voltage switching point of nor gate has a low value than ideal value of 2. The propagation delays of the new current mode logic are compared to those of equivalent gates implemented in conventional cmos logic. In this tutorial, we will examine mosfets using a simple dc circuit and a cmos inverter with dc sweep analysis this tutorial is written with the assumption that you know how to do all of the basic things in pspice. This video shows cmos transistor logic gates nand, and, nor, and or and shows how to use spice programs to analyze the circuits. The circuit diagram below is what you will build in pspice. The above drawn circuit is a 2input cmos nand gate. Generic logic evm supporting 14 through 24 pin pw, db, d, dw, ns, p, n. The nor gate is a digital logic gate that implements logical nor it behaves according to the truth table to the right. Transistor level implementation of cmos combinational logic. The cd4007 is a general purpose mos array, consequently, there had to be some additional wiring to implement the nor gate. Ptm releases a new version for sub45nm bulk cmos, providing new modeling features of metal gatehighk, gate leakage, temperature effect, and body bias.
A model definition for a 2input cmos nand gate is shown here. This enables the use of current limiting resistors to interface inputs to voltages in excess of vcc. Lab6 designing nand, nor, and xor gates for use to design. Design of a 3input nand gate and its simulation using modelsim. Build the nand gate circuit from prelab on ltspice. Oct, 20 using ltspice and irsim, here are the simulations of the logical operation of the gate for all 4 possible input. Dennis fitzpatrick, in analog design and simulation using orcad capture and pspice second edition, 2018. I got the transient curve for v1,v3 and v4 but not sure those are correct. Or, both the ptree and the ntree are conducting causing the output to be midlevel and lots of current consumption.
Now since its a nor gate i would expect a constant 0v at its output but pspice produces. In order to force pspice to perform a bias point calculation, analog elements need to be inserted into the circuit. Using ltspice and irsim, here are the simulations of the logical operation of the gate for all 4 possible input. Cmos nor gate weird simution result in pspice all about. Spice simulation cmos vlsi design slide 24 power measurement qhspice can measure power instantaneous pt or average p over some interval. Cadence capture and pspice tutorial this tutorial is intended to give you needed elements for using cadence capture and pspice to design and simulate the digital logic circuit in homework 2a, problem 2. The pspice simulation environment is available on the general access labs gal in discovery park.
The first part is an and gate and second part is a dot after it represents a not gate. It is quite similar to pspice lite but is not limited in the number of devices or nodes. To one input i applied a constant 5v and the other input is a 05v, 1khz square wave. Layout design of a cmos inverter using any layout design tool. This is a convenient option for creating cmos combinational logic circuits. Cd4011b, cd4012b, and cd4023b nand gates provide the system designer. Jul 14, 2015 the exor gate is defined as, the hybrid logic gate with 2 or more inputs to perform the exclusive disjunction operation. Its made up of the parallel connection of a nmos and a pmos device. The highspeed cmos hct logic family offers the broadest range of functions in the industry.
The circuit output should follow the same pattern as in the truth table for different input combinations. We carried out performance analysis of nand and nor logic gates at 14nm technology node, to find out the propagation delay and the average power dissipation as shown by the considered gates. Even the free download version is capable to simulate simple circuits with infineon mosfets, which are available on the infineon homepage in the internet. Compare a typical nand gate to a nand gate with crosscoupled nmos transistors.
Logic nor gate tutorial the logic nor gate gate is a combination of the digital logic or gate and an inverter or not gate connected together in series the inclusive nor notor gate has an output that is normally at logic level 1 and only goes low to logic level 0. For pspice simulations, do not forget to download the library file 3250. Lab6 designing nand, nor, and xor gates for use to. Pdf performance analysis of nand and nor logic using.
Mosfet pspice simulation 5 4 pspice simulation models pspice is a commonly used simulation tool. Launch pspice capture student by leftclicking your mouse on startpspice student capture student. It shows ltspice for windows and mac as well as oregano. Ee 307 cmos nand gates for f04 mohat project vdd 1 0 2. Exclusivenor gate tutorial with exnor gate truth table. Cmos transistor logic gates and spice analysis ltspice. Now lets understand how this circuit will behave like a nand gate. Now to make a nor gate, using 4 mosfets just like the nand gate. Cadence tutorial cmos nand gate schematic, layout design and physical verificationassura tutorial duration. The low voltage cmos lvc logic family contains a feature rich logic portfolio providing an extensive selection of products for use in 3. For these reasons, the delay time is measured with respect to a reference voltage level vref, or the threshold voltage.
Lt spice is a free spice simulator with schematic capture from linear technology. Help using the pspice simulation examples from is found here unfortunately, the pspice implementation of the bsim4 mosfet model used in many of the books. This will cause pspice to add digital to analog interface circuits into the netlist. It approaches the zero faster than the conventional method. A high output 1 results if both the inputs to the gate are low 0. Cadence capture and pspice tutorial purdue university. Need help for simulating cmos nand logic gate using spice. Unfortunately, the pspice implementation of the bsim4 mosfet model used in many of the books examples is inaccurate and the simulations often dont converge. Nor is the result of the negation of the or operator.
The output of a xor gate is equal to 1 if the two inputs are both different, and is 0 if they both have the same logic value. Aug 04, 2015 the above drawn circuit is a 2input cmos nand gate. Mce 3 micron cmos processes parameters process 2 nmos model mos type is enhancementmode. Prove that the revised version of the and gate shown in gopalans errata performs the desired and logic function. Cadence pspice technology offers more than 33,000 models covering various types of devices that are included in the pspice software. To make it easy, just copy and change the schematic file used for the nand gate, to avoid tediuos work. The exor gate is defined as, the hybrid logic gate with 2 or more inputs to perform the exclusive disjunction operation. Schematics screen view showing and, or, nand, nor, and exor gates with termination subcircuits and logical bias levels displayed. You should update the device parameters based on your lab 7 results. Cmos current mode logic that can be used to implement the high precision, speed critical elements of the mixedsignal systems. Pspice model library includes parameterized models such as bjts, jfets, mosfets, igbts, scrs, discretes, operational amplifiers, optocouplers, regulators, and pwm controllers from various ic vendors. Power electronics simulation using pspice by suman debnath. May 08, 2014 cadence tutorial cmos nand gate schematic, layout design and physical verificationassura tutorial duration.
Another very common integratedcircuit gate is the nor gate shown in fig. Cmos current mode logic gates for highspeed applications. Logic nor gate tutorial with logic nor gate truth table. If both the inputs are same, then the output is low. Features and benefits complies with jedec standard no. The table of combinations for a twoinput xor gate is given in table 6. The output of 2 input xor gate is high only when one of its inputs are high.
Xiong this tutorial will guide you through the creation and analysis of a simple mosfet circuit in pspice schematic. Spice simulation of a circuit used in cmos design to pass or not pass a signal. It can also in some senses be seen as the inverse of an and gate. The pspice simulation clearly shows that the proposed nand gate is more desirable than conventional nand gates because it resembles the actual nand gate more closely. Following the instructions shown in the lab manual, the cd4007 was wired as shown in fig. The result is that sometimes neither the ptree nor ntree are conducting and therefore the output is floating. Transient simulation of a cmos nand gate using pspice. Run a dc sweep of the nand circuit by sweeping vin2 from 0v to 10v with increments of 1v. The proper way to test a 4 input nor is to use only 4 voltage sources and drive i0i2, i1i3, i4i6, and i5i7. The tutorial is intended to be followed on a computer in. So it is clear that during the operation of nand gate, the inputs are first going through and gate and after that, the output gets reversed, and we. This circuit was created by a member of the community and has no affiliation to the circuit diagram project.