Nonsinusoidal Signal Geneatos ectangle, tiangle, saw tooth, pulse, etc. Multiibato cicuits: astable no stable states (two quasi-stable states; it emains in each state fo pedetemined times) monostable one stable state, one non-stable state bistable two stable states Fom one stable state the cicuit switches in the othe state unde the action of an contol signal (input signal). Fom one non-stable state the cicuit switches in the othe state automatically.
Nonsinusoidal signal geneatos ae based on chaging and dischaging a capacito; the oltage acoss the capacito is futhe compaed with two thesholds using a hysteesis compaato in the time domain Defining elation between cuent and oltage i d ( t) i ( t) dt onsideing finite aiations: i t
cicuit time domain analysis cicuit with oltage souce I i d i ( t) d dt ( t) t i ( t ) ( t) t t I dt d ( t) dt I t t time constant of the cicuit t t ( t) (0) e ( e ) ( )
cicuit with dc oltage souce t t ( t) (0) e ( e ) ( ) (0) 0; ( ) I ; () (t) (0)
Astable multiibatos (elaxation oscillatos) Opeating pinciple the time aiation of the oltage acoss the capacito is exponential type if the oltage acoss the capacito is fed to a PF compaato, a ectangula wae is obtained
) ( (0) ) ( t t e e t hh hl Astable multiibatoectangula signal geneato t t t O D ) ( D
t ( t t ), hh hl e c e c ; c ln t ( t t ), 3 hl hh e d e d ; d ln Geneally c d ln ln c d If = ln3,
a) hl hh 0 0 0 Example ± PS = ±, =0kΩ, =0kΩ, =7.5kΩ and =0nF. he op amp is a ail-to-ail type. a) What ae the minimum and maximum alues fo the oltage acoss the capacito? b) What is the fequency of the ectangula signal? c) Modify the cicuit fo an adjustable fequency between f min =0.8kHz and f max =8kHz? 4 0 4 0 0
b) c) 0 0 0 3 3 ln 7.5k0nFln 03.5μs 3 f 9.7kHz 66 ln ln.386 ' min.386 fmax ' 9kΩ =8.87kΩ (%)..386 f.3868khz0nf max max f ' min.386 P P 9 ' P=00kΩ 98.87 79.8k
Astable multiibato with an integato and a compaato ectangula and tiangula signal geneato o t t hl hh
d c In geneal If hh hl 4 dischage d i i 0 t c t hh t hl t hh 4 f 4 hl hh d hl ;
Example At satuation the output oltage of op-amps is within of the supply a) What is the amplitude of the tiangula oltage? b) What is the oscillation fequency? c) What is the maximum alue of the cuent to the output of each op amp?
he independence of the supply oltage OPIONAL Z 0,7; 0,7 Z he eese-biased base to emitte junction behaes as a Zene diode, egulating the oltage at a oltage dependent on the tansisto type and on the emitte cuent (5 8 ).
Fequency adjustment ' o hh hl 4 ' ' ' If one can set k the peiod () can be adjusted by adjusting the k facto
P f f f 4 4 min max 4 ; 4 Fequency adjustment - cont. ; If ; If 4 4 ' ' o f o o o P ' o f max f min
OPIONAL Offset adjustment of the tiangula oltage Fom Pa one can moe the hysteesis along the hoizontal axis, thus adjusting the offset (dc leel) of the tiangula oltage. hl a hh a a max 5 P a P a 6 6 PS 5 P 5 a 6 3.75 PS
OPIONAL Offset adjustment of the tiangula oltage amin 5 P 6 a 6 PS 5 P P a 5 6 3,75 PS he offset can be adjusted between o max 3,75 5; omin ( 3,75) 5 33 33
Specialized integated cicuits fo signals geneation 8038 - Pecision Waefom Geneato/oltage ontolled Oscillato (tiangula, squae, sine, sawtooth, pulse) OBSEE PODU NE566 - Function geneato O, squae, tiangula - MHz AD9833 - Low powe, pogammable waefom geneato: sine, tiangula, and squae wae. No extenal components. Fequency and phase ae softwae pogammable. 3-wie seial inteface. Powe-down function (SLEEP). 0 MHz to.5 MHz output fequency ange. 555 - highly stable deice fo geneating accuate time delays o oscillation (astable and monostable)
lock geneatos OPIONAL Quatz-cystal oscillato f 0 =,, 4, 5,, 0MHz f 0 =4,388MHz - ideo adapte in pesonal computes f 0 =3,768KHz - digital wist watch, diide by 5 to get Hz NO gates oscillato