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Example Circuits

Here you can download some schematics to test with Qucs. (Qucs schematic files are plain text files!) All users of Qucs are invited to contribute to these examples. If you want to share a schematic or circuit model do not hesitate to do so.

Simulation Examples

DC simulation bridge.sch two-dimensional DC sweep
Mirrors_prj.tar.gz collection of current mirror schematics using mos and bipolar
charac.sch output characteristics of a bipolar transistor
diff1.sch large-signal characteristic of a differential amplifier
fgummel.sch forward gummel characteristic of a bipolar transistor
rgummel.sch reverse gummel characteristic of a bipolar transistor
preregulator.sch simple series pre-regulator circuit
AC simulation swr_meter.sch circuit of an SWR meter
gyrator.sch a primitive gyrator circuit
resonance.sch shows voltage overshot of series resonance circuit
stab.sch simulates stability of feedback circuit
active_bp.sch a simple bandpass filter with OpAmp
active_lp.sch active 6th order Chebyshev low-pass filter
bbv.sch a BJT broadband amplifier circuit
singleOPV.sch subcircuit of an small, internally compensated MOS OpAmp
gain.sch simple example for "singleOPV.sch" (needs the circuit above to be run)
notch.sch a 50Hz notch filter realized with OpAmp gyrator
selective_amp.sch classic selective RF amplifier
Amp4.zip audio amplifier provided by John H. Ludwig
MillerAmp_prj.zip general purpose amplifier provided by John H. Ludwig
bjt_noise.zip simple flicker noise simulation for a BJT provided by Antonio
1838MHz_PLL_prj.tar.gz 1838MHz PLL modelling including noise provided by M.J. Head
groupdelay_ac.sch group delay of a Butterworth filter using AC simulation
qucs-radiometer-model.tgz radiometer model provided by Andrea Zonca
Transient simulation mixer.sch a double-balanced mixer
lf_osci.sch an oscillator for low-frequencies
rf_osci.sch a Peltz oscillator
colpitts.sch a colpitts oscillator with JFET
classic_osci.sch a classic oscillator design
multiplier.sch a charge-pumped voltage multiplier
active_mixer.sch an active, single-balanced mixer
gilbert.sch a gilbert cell mixer
sym_osci.sch a symmetrical MOSFET oscillator
schmitt.sch a schmitt trigger circuit
colpitts_base.sch a colpitts oscillator in common-base circuit
supply.sch a conventional power supply
chargepump.sch a charge-pump circuit doubling the voltage
lc_osc.sch a symmetrical LC CMOS oscillator
single_balanced.sch single-balanced CMOS mixer
Puls3b.sch fast transient pulse generation
sawtooth-1.sch sawtooth generator using simple thyristor, thanks to Oswald
sawtooth-2.sch sawtooth generator using opamp integrator, thanks to Oswald
sawtooth-3.sch sawtooth generator using flip-flop
sawtooth-discreet.sch sawtooth generator using thyristor, thanks to Oswald
time_resistor.sch time-dependent variable resistor
vfile_test_tran.tar.gz test of file-based voltage source
fullwaverectifier_1.sch full-wave rectifier using a transformer and 2 diodes
fullwaverectifier_2.sch Gratz bridge rectifier: a full-wave rectifier using 4 diodes
buckconverter.sch buck converter (step-down DC-DC converter) circuit
boostconverter.sch boost converter (step-up DC-DC converter) circuit
buckboost.sch inverting buck/boost converter circuit
S-parameter simulation elliptic_5th.sch a 5th order low pass elliptic filter
chebyshev1_5th.sch a 5th order low pass Chebyshev type 1 filter
fhr01fh.sch small-signal model of a Fujitsu HEMT (including noise analysis)
giacoletto.sch modified Giacoletto equivalent circuit
fet.sch small-signal model of a high gain FET (subcircuit)
fet_noise.sch noise matching of the FET in fet.sch
microstrip.sch simple examples how to use microstrip components
bpf_10Ghz.sch a microstrip band pass filter created by Toyoyuki Ishikawa
opamp_gyrator.sch gyrator with operational amplifier
wilkinson.sch an ideal Wilkinson divider
2StageAmplifier_prj.tar.gz building a two-stage RF amplifier with stabilization, noise and power matching
groupdelay_sp.sch group delay of a Butterworth filter using S-parameter simulation
SmithChartTest.sch Smith chart example test with a band pass filter
Digital simulation DigitalAdder_prj.tar.gz four-bit adder using one-bit halfadders and fulladders
flip_flops_models_tran_prj.zip collection of flip-flop models usable for digital as well as transient simulation
BCD_prj.tar.gz four-bit synchronous BCD counter
Harmonic balance diode_hb.sch very simple diode setup for demonstration purposes only

Simulation Models

Macro and circuit models LM317_prj.tar.gz LM317 voltage regulator(s) using different SPICE models
555_examples_prj.tar.gz famous 555 timer macromodel and examples
IdealBalun.sch ideal balun model
LPF-Balun2.sch low-pass filter using ideal balun
LPF-Balun3.sch another low-pass filter using ideal balun
Device models curtice1_MESFET_prj.tar.gz Curtice level 1 MESFET model
shot.sch universal shot noise subcircuit
flicker.sch flicker noise subcircuit
triode.sch triode tube model
pentode.sch pentode tube model
Complete projects RADAR2010_prj.zip project on radar circuits (attenuators, duplexers, limiters, phase shifters) and subsystems (T/R modules and reflect arrays) for a tutorial (tested with version 0.0.15) given at the 2010 IEEE Radar Conference, by K. Van Caekenberghe
PVcell_Miguel_Pareja.zip Photovoltaic Cell simulation with QUCS, by Miguel Pareja
High_Voltage_Supply_prj.tar.gz High voltage power supply, by Richard Crozier
UHF_Amplifier_prj.tar.gz UHF amplifier with optimization, by Richard Crozier
BSIMTests_prj.zip BSIM3 and BSIM4 test examples (tested with version 0.0.18), by Mike Brinson