IP DESIGN REPORTING

DATA SHEET

vsdbbcud4f

Bi-directional Buffer with Non-inverting CMOS input and gated Pull-down and Pull-up, Strength 4ma @ 3.3V, Normal, High noise

DESCRIPTION OF IP

1. vsdbbcud4f is a GPIO pin (General purpose input/output)
2. The GPIO pin is controlled by the user to get a desired mode of the whole chip
3. The input/output mode can be selected by giving the enable pin to logic high or low
4. Both the buffers are connected in a bidirectional fashion which allows the data to flow in either of the direction

SYMBOL

Block diagram

PIN DESCRIPTIONS

1. pin A is where the input is given
2. pin EN is the enable pin which is used to determine the mode of the circuit (input/output)
3. pin PI is the input to the PAD cell
4. pin PUEN is used to pull-up the input when it is in floating state
5. pin PDEN is used to pull-down the input when it is floating state
6. pin Y is the output
7. pin PO is the output of the PAD cell

TYPICAL PERFORMANCE CHARACTERISTICS

expected characteristics

according to https://www.vlsisystemdesign.com/ip/

pre-layout characterstics

LT-Spice circuit diagram

LTspice output graph for a simulation time of 100ms

characterstics of inputs and outputs of GPIO circuit are shown in the plot.Inputs:A,EN,PUEN,PDEN,PI Outputs:Y,PO when the enable is 0 output Y is same as the input A when enable is 1 output varies according to the truth table in https://www.vlsisystemdesign.com/ip/ for any value of input A

ngspice plots

ngspice plots for GPIO LTspice circuit EN,A and PI,Y,PO

post-layout characterstics

cmos magic layout

ngspice plots for cmos layout

ngspice cmos.sp

CMOS characterstics in NGspice plot

nand gate magic layout

ngspice plots for nand layout

ngspice nand.sp

NAND inputs NGspice plots A and B

NAND output NGspice plot

tristate magic layout

ngspice plots for tristate layout

ngspice tristate.sp

NGspice plots for tristate buffer inputs A and EN

Ngspice plots for tristate buffer output

gpio magic layout

ngspice plots for gpio layout

ngspice gpio.sp

Ngspice plot for PO post-layout

Ngspice plot for PI and Y post-layout

Ngspice plot for A and EN post-layout

FUTURE WORK

ISSUES:

1. performance of the pre-layout simulation is limited to milliseconds simulation time should update it to get all the plots in nanoseconds since we are using everything in 180nm technology
2. PUEN and PDEN are not included in post layout simulation yet

these issues are to be updated in further releases

IP USAGE

TOOLS REQUIRED TO USE THE IP

For pre-layout simulation

steps to install and use ltspice for windows10

1. Download LTspice from here ltspice_download
2. Now click on the download button for windows.
3. Now click on the application ltspice from your downloads and accept and continue.
4. The simulator is installed and is ready to use.
5. download the ltspice zip file from the repository
6. open the circuit with a file .asc file extension
7. goto view->spice netlsit and copy the content in there
8. open a new text file and paste the spice netlsit and add the command lines according to ngspice
9. save the text file with a .cir extension

Ngspice installation and usage for windows 10

ngspice is the open source simulator. Follow the steps below to install ngspice on windows10:

1. Click on this to download ngspice software.
2. Click on the download button.
3. You are directed to the download page. Then follow the installation steps.
4. The software is now donloaded and ready to use.
5. open ngspice->spice64->bin and save the .cir file in this location also add the model files in the same location
6. now open ngspice application and type filename.cir to get the corresponding output graphs

For post layout simulation

MAGIC installation and usage in linux mint

1. goto administartion->synaptic package manager->search->magic
2. mark it for installation and proceed with the next steps
3. once the installation is completed close the synaptic manager
4. download the above files from repository and unzip them
5. open the terminal in the folder and tpye magic -T osu180nm.tech filename.mag for example if we want to open the gpio layout type magic -T osu180nm.tech gpio.mag
6. This opens the layout
7. now goto the corresponding tckon dialoge box and type extract all which generates a netlist with the extension ext now to convert into spice type ext2spice
8. a spice netlsit is generated open it and add the pmos and nmos model files and some lines to run it through ngspice
9. save the files with a .sp extension

Steps to install Magic VLSI on LINUX

1. Download the magic.sh file

2. Copy paste the below commands one after another

cd Downloads/
chmod +x magic.sh
./magic.sh

Magic tool will be opened with minimum technology file by default. Follow below steps to open magic with osu180nm tech file.

3. Download the osu180nm.tech file from the uploaded files. Copy and paste the entire content in Text Editor and save it as osu180nm.tech.

4. Open the Terminal and copy, paste the commands mentioned below.

sudo cp osu180nm.tech /usr/local/lib/magic/sys/
cd /usr/local/lib/magic/sys/
ls 
cd
clear

5. You have successfully added osu180nm.tech file!

6. Just open the terminal and type magic -T osu180nm.tech filename.mag to begin layout.

Ngspice installation and usage for linux mint

1. goto administration->synaptic package manager->search->ngspice
2. mark it for installation and proceed with further steps
3. open in terminal->ngspice and check if it is working to come out of ngspice type exit in terminal
4. type ngspice filename.sp and check the output graphs

Steps to install LTSpice XVII on LINUX

1. It's not directly supported, so we need to download WineHQ. Wine is a linux software that creates windows environment and allows you to run various windows programs.
2. Copy paste the commands mentioned below one after the other in the terminal for downloading and installing.

sudo dpkg --add-architecture i386
wget -O - https://dl.winehq.org/wine-builds/winehq.key | sudo apt-key add -
sudo add-apt-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ focal main'
sudo apt update
sudo apt install --install-recommends winehq-stable

3. Download LTSpice.
4. Click on Download for Windows.
5. Install it by clicking on -> next.
6. After installing , click on open with WineHQ windows program loader.

LTSpice is now installed and you can design the circuit```

Steps to clone the IP onto UNIX based systems

Cloning a github repository creates a local copy of a remote repo and this allows us to make any changes to the files locally without affecting the main repository. To clone the IP onto your system copy paste the commands given below.

$  sudo apt install -y git
$  git clone https://github.com/gowthaminalla/vsdbbcud4f.git
$  cd vsdbbcud4f/magic

Contact information:

1. Nalla Gowthami, Electronics and instrumentation engineering, NIT Rourkela, gowthaminalla1821@gmail.com
2. Kunal Gosh Director, Vsd Corp Pvt.Ltd, kunalpgosh@gmail.com
3. Phillip Guhring, Software architect at Libresilicon Association pg@futureware.at
4. Dr.Gaurav Trivedi Co-principal investigator, EICT academy, and associative proffessor, EEE depatement, IIT Guwahati, trivedi@iitg.ac.in