VOLTAGE CONTROLLED OSCILLATOR- D E S C R I P T I O N

SoUdSlcile

SSM 2033

VOLTAGE CONTROLLED OSCILLATOR-

D E S C R I P T I O N

T h e S S M 2 0 3 3 i s a p r e c i s i o n v o l t a g e c o n t r o l l e d o s c i l l a t o r d e s i g n e d s p e c i f i c a l l y fo r t o n e g e n e r a t i o n in e l e c t r o n i c m u s i c . l t h a s s a w - t o o t h , t r i a n g l e , a n d v a r i a b l e w i d t h p u l s e o u t p u t s . S i m u l t a n e o u s e x p o n e n t i a l a n d p r o p o r t i o n a l l i n e a r s w e e p i n p u t s c a n c o n t r o l o p e r a t i n g fr e q u e n c y o v e r a 5 0 0 , 0 0 0 - t o - 1 ra n g e . O n - c h i p l o w i n p u t b i a s s u m m e r a n d c o n t r o l o p a m p s h a v e b e e n p r o v i d e d . T h e p u l s e c o m p a r i t o r , w h i c h h a s b u i l t - i n h y s t e r e s i s f o r c l e a n s w i t c h i n g , c a n c o n t r o l p u l s e w i d t h d u t y c y c l e f r o m 0 t o 1 0 0 % . H a r d a n d s o f t s y n c i n p u t s m a k e p o s s i b l e a r i c h v a r i e t y o f m o d u l a t i o n a n d h a r m o n i c l o c k i n g e f f e c t s . ln a d d i t i o n , t h e o p e r a t i n g te m p e r a t u r e o f t h e c h i p i s r e g u l a t e d m a k i n g e x t e r n a l t e m p e r a t u r e c o m p e n s a t i o n u n n e c e s s a r y . O n l y o n e t r i m ( v o l t s / o c t a v e ) is r e q u i r e d f o r n o r m a l o p e r a t i o n .

F E A T U R E S

Mlcro

Technologry

lor Music

F u l l o n - c h i p t e m p e r a t u r e c o m p e n s a t i o n . 5 0 0 , 0 0 0 - t o - 1 s w e e p ra n g e .

S i m u l t a n e o u s s a w t o o t h , t r i a n g l e , a n d v a r i a b l e w i d t h p u l s e o u t p u t s .

S i m u l t a n e o u s e x p o n e n t i a l a n d p r o p o r t i o n a l l i n e a r s w e e p in p u t s .

O n - c h i p s u m m e r a n d c o n t r o l o p a m p s . E x c e l l e n t e x p o n e n t i a l c o n f o r m i t y .

A l l o u t p u t s a r e s h o r t c i r c u i t p r o t e c t e d . H a r d a n d s o f t s y n c i n p u t s .

P u l s e d u t y c y c l e v o l t a g e c o n t r o l l a b l e f r o m 0 t o 100%

P u l s e c o m p a r i t o r h a s b u i l t - i n h y s t e r e s i s . 1 0 0 n s e c s a w t o o t h d i s c h a r g e t ' ' n e .

O n l y v o l t s / o c t a v e t r i m r e q u i r e d f o r n o r m a l o p e r a t i o n .

I I I t

I I

! I I t

I

t - 1

2 1 7

3 1 6

4 1 5

5 1 4

6 1 3

7 1 2

8 1 1

I 1 0

C R T + V - V T R I O U T S O F T S Y N C S U M I N S U M O U T P U L S E M O D I N P U L 6 E O U T C I R G N D

H E A T + V H F T E X P O L I N B A S E G N D

S A W O U T H A R D S Y N C H E A T G N D

P I N O U T ( T O P V I E W )

C F T ' V

I

BASE G N D , O A

B L O C K D I A G R A M

S o l i d S r a r e M i c r o T e c h n o l o g y f o r M u s i c , In c . , 2 0 7 6 8 W a l s h A v e n u e , S a n t a C l a r a , C A 9 5 0 5 0 , U S A

l 4 0 8 l 7 2 7 - 0 9 1 7 T e l e x 1 7 1 1 8 9 . P A T E N T S A P P L I E D F O R

R E V I S E D 5 8 1

S P E C I F I C A T I O N S * 25"C

* V = * 1 5 V . - V = I N T E R N A L R E F E R E N C E

O P E R A T I N G T E M P E R A T U R E - 1 0 " C to +55oC

S T O R A G E T E M P E R A T U R E - 5 5 o C to +125"C

P A R A M E T E R M I N

T Y P

P o s i t i v e S u p p l y C u r r e n t Max Heater Current

Positive Supply Voltage Range N e g a t i v e S u p p l y V o l t a g e R . n g " ( 1 )

8 . 0 30.0

9 . 0 4 . 5

r 0 . 5

3 7 1 5 - 1 5

1 3 . 3 4 5 1 8 - 1 8

m A m A V V Sweep Range

I n t e g r a t o r In p u t B i a s C u r r e n t Control Circuit Offset M a x O p e r a t i n g F r e q u e n c y M a x C h a r g i n g C u r r e n t E x p o n e n t i a l S c a l e E r r o r

2 5 0 K : 1 - 5 . 0

2 7 270

1 M : 1 0 . 3

0 33 330 0 . 0 5

1 +5 44 440

o.2

n A m V k H z

sA

%

C = 1000 pf

-90 mV < V^ < +90 m!

Sawtooth Peak Level Sawtooth Discharge Level Sawtooth Discharge Time

Sawtooth Output Short Circuit Current

9 . 7 5

5 . 6

1 0 . 0 200 1 0 0 7 . 5

10.25 350 9 . 4

V m V nsec

m A Triangle Peak Level

T r i a n g l e T r o u g h L e v e l

T r i a n g l e O u t p u t S h o r t C i r c u i t C u r r e n t

4 . 7 5 -250

I

5 . 0 0 1 1

5 . 2 5 +250 1 4

V m V

m A V p i n 3 : G N D P u l s e U p p e r L e v e l

Pulse Lower Level P u l s e F a l l T i m e P u l s e R i s e T i m e

P u l s e M o d u l a t i o n I n p u t B i a s C u r r e n t

5 . 8 - 1 0 0

0 . 7 5

6 . 5 0

1 3 2 . O

7 . 2 + 1 0 0

6 . 0

V m V p s e C

psec p A

P i n 8 h a s 1 5 K t o G N D

@ 5 0 H Z V p i n T ) V p i n 1 2 C o n t r o l a n d S u m m e r O p A m p s

Input Offset Voltage lnput Offset Voltage Drift I n p u t B i a s C u r r e n t l n p u t B i a s C u r r e n t D r i f t

Frequency Drift With Temperature Basic Loop

With Exoonential Converter(z)

- 5

-20 - r 0 0

o.2

40 50

+5 250

+20 + 1 0 0

m V pVlC"

n A pA/Co ppm/Co ppm/C"

o"c < TA< 45oc

odc < To< 4s"c

V " = G N D V" = i26 mV

N o t 6 : ( 1 ) S e r i e s c u r r e n t li m i | n g r e s i s t o r re q u i r e d t o r n e g a t i v e s u p p l i e s g r e a t e r th a n - 6 V (2) Unco*pensated drift under the same conditions is 33OO ppm/C' @ 25'C.

'Final specifications may be subiect to change.

The schematic above show the typical connection of the SSM 2033 as an electronic music VCO. The control circuit section is redrawn for easy reference (figure 1). Any number of input voltages can be summed by amplifier A1 which drives the exponential input attenuator to pin 16. Amplifier A, forces the current in Q1 to be equal to the sum of the reference current, established by Rr, and the linear FM voltage. The current in the output transistor 02 is:

E KT = 3 1 . 1 m V @ 8 5 " C

q

Propagataon delay and discharge time can cause a deviation f rom true exponentiality al lrequencies above 5kHz. To correct for this effect, transistor Q3 provides feedback to the exponentialcontrol input. At low f requencies (currents), Q3 will have a negligible effect on the voltage at the base of Q.'. At high f requencies (currents), Q3 will correct for the tendency of the oscillator to track flat. Since 5kHz is about the upper limit for most musical applications, pin 1 7 can be grounded and R3 and R4 replaced with a 1 K 1% resistor. For accu - rate operation above 5kHz, R3 Ro are chosen to give a true last octave.

- V ^ q i kT l o = ( V + / R l + V L / R 2 ) e E '

+V (UNREGULATED) 3 . 0 1 M 1 %

T o.tpt

+ (GND PIN s)

"

? l,"t (GND PlN 10)

-l t-:-

1 2 3 4 5 6 7 I o

1 8 1 7 1 6 1 5 1 4 1 3 ' t 2 1 1 1 0 G N D ( H E A T )

54.9K 1 % INPUT (OPTIONAL)

S I U N M P M U E T R ( S )

. l O O K 1 % I

r o o x r c 6 l

l o o K ' l

1o/o PULSE MOD

1 OOOpf

INPUT PULSE

OUT 1 5 K 3.3K

HARD lOOOpt

i-"J,?>--

(OPTIONAL)

GND (CRT)

T Y P I C A L C O N N E C T I O N

2 . 2 K

'Polystyrene

* * C e r a m i c ( L o c a t e close to l.C. )

V/OCTAVE

l".r

l

O . 1 p f

R' = 3.01M 19"

100K 1 0 0 K 47tl 1o/"

1 . 5 M

1o/o

100K

'lo/"

100K

R . + f u = 1 6

0 . 1 s f

1o/o

3 . 3 K

54.9K

1o/"

100Opf

II

II

+

R.

1o/"

r

., --V" (

"

- 55.9K

F I G U R E T _ C O N T R O L C I R C U I T

The SSM 2033 has an on-chip temperature sensor and heater which regulates the chip temperature to 85'C. The kT/q term in the exponent of the equation above is now a fixed value independent of ambient temperature. Operating temperature is reached 30 to 40 seconds after device power-up. Current drawn by the heater will decrease as ambient temperature rises. The temperature stabilization also insures that errors caused by offset drift with temperature in the summer and control op amps will be extremely small. (SEE NOTE LAST PAGE.)

T h e o u t t l u t c u r r e n t o i t h e c o n t r o l c i r c u i t i s f e d t o a n i n t e g r a t i n g a m p l i f re r w h r c h c r e a t e s t h e s a w t o o t h w a v e f o r m . T h e i n s t a n t a n e o u s sawtooth output is compared to a reference voltage that is two-thirds of the positive supply. Sawtooth discharge is accomplished by a capacitorless one-shot which delivers a pulse to the discharge transistor when triggered by comparator C1.

The triangle converter and pulse width comparator shape the sawtooth to provide the other two waveform outputs. The 27K resistor between the positive supply and the soft sync pin centers the sawtooth for proper triangle conversion. Comparator C2 compares the pulse width modulation input voltage to the instantaneous sawtooth output to create a pulse that can have a duty cycle between 0 and 100%. The control range on the PWM input is between 0 and 10 V. C2 has about 180 mV of built'in hysteresis to give fast clean transistions on both the rising and falling edges of the output.

The hard and soft sync features provide additional means for timbre modulation and additive synthesis. The hard sync input senses a falling edge. such as another 2033's sawtooth discharge, and forces an immediate discharge of the synced 2033. The resulting waveform has a complex harmonic structure whose pitch is that of the incoming oscillator (figure 2). The soft sync input also a c c e p t s a f a l l i n g e d g e b u t i t w i l l f o r c e d i s c h a r g e o n l y i f t h e s y n c e d 2 0 3 3 i s w i t h i n 2 4 0 K l ( R 3 + 2 . 4 K 1 % o f d i s c h a r g e . T h i s e n a b l e s one to phase-lock two oscillators to freguencies that are exact small integer ratios of one another (figure 3). By mixing the wave- forms of the two oscillators, complex additive synthesis can be performed.

NOTE: The time required f or the 2033 (s) lo become temperature stabilized afler system lurn on can be eliminated by wiring the powef supply so lhat the oscillators operale as long as the system ii pugged in. This is similar to the "instant on" feature in tube T.V. sets.

1 000pf

>--l

H A R D S Y N C I N

R5 = 22K 3,o9ef

>-*--l h

S O F T T

S Y N C I N

P I N 1 1 3 . 6 K ( T N T E R N A L )

H A R D I S Y N C l N r

S A W T O O T H '

t-

O U T P U T :

F I G U R E 2 _ H A R D S Y N C

SOFT S Y N C I N

- - 1 0 v

G N D

G N D

TO INTERNAL LOGIC

3 . 6 K ( T N T E R N A L )

TO C1

( T N T E R N A L ) - - - l

SAWTOOTH O U T P U T

9V

G N D FIGURE 3_ SOFT SYNC

SoUd Stcrte Mlcro ffir Teghnologry

lor Music !'

@ tso soLrD srATE MrcRo rEcHNoLocy. ALL RTGHTS R E S E R v E D .

Solid State Micro Technology cannot assume responsibility for use ol any circuitry dercribed oth€r than the circuitry entirely embodied in an SSMT p r o d u c t . No other circuit licenses are implied. Solid Stare Micro Technology reserves thc right. at any tima without notice, to change said circuitry.