Transcript Circuit Analysis and Simulation of basic circuits
TECHNICAL WORKSHOP MARATHON 2012
CIRCUIT ANALYSIS USING NGSPICE
VISHNU V 2 nd Year M.Tech VLSI and Embedded Systems Govt. Model Engineering College, Thrikkakara
CONTENTS
SIMULATING A CIRCUIT IN NGSPICE
EXAMPLE CIRCUIT
NETLIST CREATION USING gEDA SCHEMATIC EDITOR
ANALYSIS OF BASIC CIRCUITS
HIGH PASS CIRCUIT AND DIFFERENTIATOR
LOW PASS CIRCUIT AND INTEGRATOR
RECTIFIER CIRCUITS
CLIPPER CIRCUITS
CLAMPER CIRCUITS
Simulating a Circuit using NGSPICE
Steps
Mark the nodes present in the circuit using numbers or symbols (Try to mark Ground node by '0' ) Write the netlist (
use texteditors such as gedit or vi editor etc
)for the circuit satisfying all the rules and regulations.
Save the netlist using .cir
or .net
extension.
3
Simulating a Circuit using NGSPICE
Open ngspice command window by typing
ngspice
in terminal(
bash,sash
etc) Give the name of the saved netlist in
ngspice command window
.
EXAMPLE CIRCUIT
Simulation of a simple
RC filter
using NGSPICE
EXAMPLE CIRCUIT
Here there are three nodes
n0 n1 0
Also the components present are
A sinusoidal voltage source A 3.3nF capacitor A 1k resistor
Writing NETLIST
Title Line (First Line )
A simple RC High pass filter
Component connections
V1 n0 0 SIN(0 10 1kHz) C1 n0 n1 3.3nF
R n1 0 1k
Writing NETLIST
Control Lines
.CONTROL
TRAN 0.01ms 10ms PLOT V(n0) V(n1)
END Lines
.ENDC
.END
Total NETLIST
A Simple RC High pass filter V1 n0 0 SIN(0 10 1kHz) C1 n0 n1 3.3nF
R n1 0 1k .CONTROL
TRAN 0 0.01ms 10ms PLOT V( n0) V(n1) .ENDC
.END
SIMULATION STEPS
Save the above file as
rc_filter.cir
STEP 1 :
Open Terminal and type ngspice
Terminal Open Terminal and Type ngspice Ngspice command terminal opens
SIMULATION STEPS STEP 2 :
Give the file name of the netlist we have written ie
rc_filter.cir
Give the file name of the netlist and press enter
SIMULATION STEPS TRANSIENT ANALYSIS OUTPUT BASH TERMINAL WAVE FORM WINDOW
ANALYSIS OF WAVEFORM
Analyse the waveform
O U T P U T I N P U T
PART II NETLIST CREATION USING gEDA
SCHEMATIC EDITOR
STEPS
Draw the schematic of the circuit using
gEDA schematic editor
Save the file with extension
.sch
Convert
.sch
file to
.net
file using
gnetlister.
Command :
gnetlist -g spice -o rc_filter.net rc_filter.sch
DRAWING CIRCUIT IN gEDA SCHEMATIC EDITOR SAVE THE ABOVE SCHEMATIC AS
rc_filter.sch
CONVERING SCHEMATIC TO NETLIST Output File name Schematic Name gnetlist -g spice -o rc_filter.net rc_filter.sch
NETLIST OBTAINED FROM SCHEMATIC rc_filter.net
SIMULATING THE NETLIST
SIMULATING THE NETLIST Name of the NETLIST created using gnetlister
SIMULATING THE NETLIST
SIMULATING THE NETLIST : TRANSIENT ANALYSIS Indicates Transient Analysis Final Value Increment value
SIMULATING THE NETLIST : TRANSIENT ANALYSIS
SIMULATING THE NETLIST : TRANSIENT ANALYSIS PLOT V(2) V(1)
ANALYSIS OF THE WAVEFORM GREEN COLOUR : INPUT WAVE RED COLOUR : OUTPUT WAVEFORM
WHY THE AMPLITUDE OF THE OUTPUT WAVEFORM IS VERY LESS ??
REASONS
The Circuit is a
High pass filter
, so it passes only high frequency signals.
We have given an input sinusoidal waveform of Amplitude = 10V and Frequency = 1kHz Cut off frequency of the high pass filter is given by, cutoff frequency= 1/(2*pi*R*C) Here in this case Cutoff frequency (3 dB frequency ) = 48.22kHZ
So, Give input sine wave frequency >= 48.22 kHz
MODIFIED NETLIST
A Simple RC High pass filter V1 n0 0 SIN(0 10 500kHz ) C1 n0 n1 3.3nF
R n1 0 1k .CONTROL
TRAN 0.0001ms 0.1ms
PLOT n0 n1 .ENDC
.END
NEW INPUT FREQUENCY
OUTPUT WAVEFORM
AC ANALYSIS OF HIGH PASS FILTER FOR AC ANALYSIS THE CONTROL SIGNAL IS .AC
.AC
LIN DEC 16 60 600KHz 20 1 10kHz
NETLIST FOR AC ANALYSIS OF HIGH PASS FILTER
A Simple RC High pass filter V1 n0 0 SIN(0 10 500kHz) C1 n0 n1 3.3nF
R n1 0 1k .CONTROL
AC LIN 1000 0.1Hz 1000kHz PLOT V(n1)
.ENDC
.END
AC ANALYSIS
AC ANALYSIS PLOT I
NETLIST FOR AC ANALYSIS OF HIGH PASS FILTER
A Simple RC High pass filter V1 n0 0 SIN(0 10 500kHz) C1 n0 n1 3.3nF
R n1 0 1k .CONTROL
AC DEC 10 100Hz 10000kHz PLOT DB(V(n1)/V(n0))
.ENDC
.END
AC ANALYSIS
AC ANALYSIS PLOT II
HOW A
HIGH PASS FILTER
CAN BE CONVERTED TO A
DIFFERENTIATOR
CIRCUIT
HIGH PASS FILTER AS DIFFERENTIATOR The Condition in which a high pass filter acts as a differentiator circuit is given by RC << 0.0016T
signal ; Where T = Time period of the input
Question ?
Design a Differentiator Circuit which takes a pulse waveform of frequency 1 kHz and perform its transient analysis using NGSPICE....
Take the capacitor value as C = 3.3nF
DIFFERENTIATOR TRANSIENT RESPONSE
With RESISTOR VALUE, R = 47k
DIFFERENTIATOR TRANSIENT RESPONSE
With RESISTOR VALUE, R = 10k
RC LOW PASS FILTER
RC LOWPASS FILTER AC ANALYSIS PLOT
RC LOWPASS FILTER AS INTEGRATOR
RECTIFIER CIRCUIT WRITE THE NETLIST AND PLOT THE WAVEFORMS
RECTIFIER CIRCUIT OUTPUT
CLIPPER CIRCUITS POSITIVE CLIPPER CLIPPING LEVEL : +5V WRITE NETLIST AND OBTAIN THE OUTPUT WAVEFORM
POSITIVE CLIPPER OUTPUT WAVEFORM +5V
CLIPPER CIRCUITS DOUBLE CLIPPER CLIPPING LEVELS : +5V and -5V WRITE NETLIST AND OBTAIN THE OUTPUT WAVEFORM
DOUBLE CLIPPER OUTPUT WAVEFORM +5V -5V
CLAMPER CIRCUITS SIMPLE POSITIVE CLAMPER CIRCUIT
OUTPUT WAVEFORM
EXPERIMENTS LAB SESSION 1.
RC HIGH PASS CIRCUIT AND DIFFERENTIATOR 2.
RC LOW PASS CIRCUIT AND INTEGRATOR 3.
RECTIFIER CIRCUITS 4.
CLIPPER CIRCUITS 5.
CLAMPER CIRCUITS
ASSIGNMENT I PLOT THE FOLLOWING WAVEFORM USING NGSPICE
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