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I
MC13020P
I
Advance Information
MOTOROU C-QUAM@ AM STEREO DECODER
MOTOROM C-QUAM@ AM STEREO .t$;i:t,
DECODER ~'~i:: `" *$1, `"::> $,,,
SILICON MO~~~&&"b lNTEGRATEO'~@lT .3;; `,;! ~~'~~~+ ~ \\.,,,..,,!\ ::$\. .,, ~ ,,.t~ .,..,, `*r~- ~$.$.
This circuit is a complete one-chip full-feature AM stereo decoding and pilot detection system. It employs full-wave envelope signal detection at all times for the L + R signal, and decodes L- R signals only in the presence of valid stereo transmission. .
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No Adjustments,
No Coils
Few Peripheral Components True Full-Wave Envelope Detection for L+ R PLL Detection For L-R
. 25 Hz Pilot Presence Required To Receive L- R
q
Pilot Acquisition Time 300 ms For Strong Signels, Time EMended For Noise Conditions To Prevent "Falsing"
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. Internal Level Detector Can Be Used As AGC Source
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PLASTIC PACKAGE CASE 738-02
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Q Detector .20 Phase Detector Osc. Feedback `F'nput 19 * `8 u
\ 3
*= +
0.0033 47 KF
'430 ;3 10:O1* 1 x I ::.?.-I;;;;a:or 0.0033
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",!",
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Tuner AGC
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sour+:,.!" ,, + PF O.oo1
~?" .?,;$~:*tp'~* "+i "$"% :\; ,.>"-,t, ~ +3 .*?* ..: '*'A@&o ~<, !'outputs .. . Xi::jq;:t,,t ,\:\.. . . c ~+~ ==
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L,,>
Osc. Input
`7 .~~+'
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Detector
Ground . Stereo Lamp Pilot Detector Input
`6 15 14
5 Error Amplifier
0.47
7 Left Output 8 Right Output Pilot Filter 13 Input 56 k ~b 9 Forced Monaural 10 Lock Co-channel 12 Input
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220 k + 0.47 4.7 k
$$,~,y ~,>+, ~ `.,, , V*,.,. .&p ;
`. +~J~ $ ~,.+
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100k Auto Monaural
,OPFF ~:;
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B subject
2.2 MF 1: =
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AGC'd Q 11 output ~
430
4.7 pF > :
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*muRata Ceramic Resonator -- CSA3.60MT7 and Temp. Comp. Capacitor -- CSC500K7
The purchase of the Motorola C-QUAM@ AM Stereo Decoder does not carry with such purchase any license by implication, estoppel or othewise, under any patent rights of Motorola or others covering any combination of this decoder with other aiementa including use in a radio receiver. Upon application by an interested Paw, licenses are available from Motorola on its patants applicable to AM Stereo radio receivers.
Iis documsntcontains information on a new produti. Specificationsand information herein
to changa without notica.
@MOTOROLA .-
INC., 19S5
ADI-725R2
C-QUAM is a trademark of Motorola Inc.
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"
MAXIMUM RATINGS
Rating Supply Voltage Pilot Lamp Current, Pin 15 Operating Temperature Storage Temperature Junction Temperature Powar Dissipation Derate above 25C TA T~tq TJ{max) pD Symbol Vcc Value 14 50 -40 to +85 -65 to + 150 150 1.25 10 Unit Vdc mAdc "c "c `c w mWPC *,\ *'X,l, $J,$<,. ,,.,'~ ,'$:. `!i., +ts., ,:1 ,:?:L*S ,*,Y *'\$,~, .?., <> .>:. .. .:+\ <+ .t::.,,f >:>'.' ,1: ,}~~.. ~{,,.\ .,.,.,.\\,~ ..}\'~:*\, I:it:p'.,.t (Unmodulated,&~~ri*;~ircuit Of .~?>? ;;:;$;+$* ,,>>.$, ~,, ,.,, 1 Unit TYP .s. ~`i''$,y~ax 6,0,]~@&jb afv''3@~,, b"" ,,, "~a ,,* :z:ti `k: "/0
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ELECTRICALCHARACTERISTICS (VCC = 8.0 Vdc, TA = 25C, Input Signal = 200 mVRMS
Figure 1 Unless Othemise Charaderistic Power Supply Operating Range Noted.) Min -- 20 Pin 3, for Full Operation L only or R only Monaural Monaural Stereo 100 16,q ..?&i.,*
Supply Line Current Drain, Pin 6 Input Signal Level, Unmodulated,
Audio Output Level, 5070 Modulation, Audio Output Level, 50% Modulation, Output THD, 5070 Modulation
s `"p ,$~~ :,.?~:*'\ ~?>{,. ;$ ,*. ~ -- Channel Separation, L only or R only, 50% Modulation *.1. ~ `"s~,, Pilot Acquisition Time, VCO locked, after relaase of forced monaura~.,?~, ti+ -- .x `~.: 20 $2, $,,RA4fl % Input Impedanca -- `$>'"'~ .~~t)~ ~ n ~.ti.:::!* `~ \..:t~t:. -- Output Impedance .s ` :,* \,~~ ) O signal 1.4 Level Detactor Filter Voltage, Pin 4, `1+'.'~: ,, -- t$~ObiNVRMS Signal ....).. .}:3:3 -- .$><$ ,.i~,, In Lock Lock Detector Filter Voltage, Pin 10 \ ,<*, -- Out of Lock .. !$$,,...,. ,-. , ,, ~ Force to Monaural, Pin 9, Pull Down for ~#@F~Mode \ $:.* .$.,+\\ > `.th, ,.~..! Pin 9, Pull Up.tw'~k,~~katic Mode 2.0 -- -- --
dB ms k~ pF Q Vdc
B
Vdc
Vdc PA Vdc @
Force to Monaural,
FIGURE 3 -- MOTOROLA C-QUAM@
(I+ L+ R)cosO -----
l+L+i Envelope is compatible with existing monaural receivers.
e 1
I Avg. Carrier I I (L- R)coso
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M070ROkA
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Semiconductor Products Inc.
/ Vcc
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FIGURE 4 -- BLOCK DIAGRAM
= + + ) 4, , 10, , Optional AGC To Tuner
6A
2, , l+L+R
1, ,
"5* ,
20, .
Env DET
l/cose
0.01
3
+e
r
+
Var Gain
7
IF Input
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4r Phase DET 9W , 1e Vco Monaural
------ r I A
-----
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Note 1: Output polarity
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See Text
dsfined for recsiver front end with L.O. abovs signal frequency.
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,$,, tt ?,. .,~t::<$. ,,,$~*:, t, $~,?~~~, INTRODUCTION "::t~i:t~ .\\+ In C-QUAM@, conventional,, ~~~d$ture amplitude modulation has been modifie~,~y ~dftipiying each axis by COSOas `shown in ~g~~j~sdfid 3. The resulting carrier envelope is 1 + L.,+~+,i~~., a correct sum signal for monaural receiver&a* "'Forstereo receivers opersting in monaural mod@$y# 25 Hz pilot signal is added to the L-R infor~~,~'n,at a 4% modulation level. `J, \*.,f')" , .:. \`t+*,<*l, .$~, THE DECOQ,~, ::$ The M~~$* takes the output of the AM IF amplifier and p~~as the complete C-QUAM@ decoding functio~r+~~~,?absence of a good stereo signal, it produces a@J&,Wgraded monaural output. Note in Figure 4 that $~$~~+ R information delivered to the output always `&mes from the envelope detector (Env DET). The MC1 3020P decodes the stereo information by first converting the C-QUAM@ signal to QUAM, and then . detecting QUAM. The conversion is accomplished by comparing the output of the Env DET and the I DET in the Err AMP. This provides the l/cos8 correction factor, which is then multiplied by the C-QUAM@ incoming signal in the Var Gain block. Thus, the output of the Var Gain block is a QUAM signal, which can then be syn0
MOTORO~ C-QUAM@ -- COMPATIB~~$"1,, .,`~''~;..?,$ }/!+ QUADRATURE AM STEREO )i~.,. ~ \i,$i$$),.
chronously detected by conventional means; The I and Q detectors are held at 0 and 90 relative demodulation angles by reference signals from the phase-locked, divided-down VCO. The output of the I DET is 1 + L+ R, with the added benefit (over the Env DET) of being able to produce a negative output on strong co-channel or noise intetierence. This is used to tell the Lock circuit to go to monaural operation. The output of the Q DET is the L- R and pilot information. THE VCO The VCO operates at 8 times the IF input frequency, which ensures that it is out-of-band, even when a 260 kHz IF frequency is used. Typically a 450 kHz IF frequency is used with synthesized front ends. This places the VCO at 3.6 MHz, which permits economic crystal and ceramic resonators. A crystal VCO is very stable, but cannot be pulled very far to follow front-end mistuning. Pull-in capability of * 100 Hz at 450 kHz is typical, and de-Q-ing with a resistor (see Figure 7) can increase the range only slightly. Therefore, the crystal approach can only be used with very accurate, stable front-ends, By comparison, ceramic and L- C VCO circuits offer pull-in range in the order of *2,5 kHz (at 450 kHz), Ceramic devices accurate enough to avoid trimming adjustment can be obtained with a matched capacitor for Cs (see Figures 1 and 5).
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MOTOROLA
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Semiconductor Products /nc.
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In the PLL filter circuit on Pin 19, Cl is the primary factor in setting a loop corner frequency of 8-10 Hz, inIock. An internally controlled fast pull-in is provided, R2 is selected to slightly overdamp the control loop, and C2 prevents high frequency instability, The Level DET block senses carrier level and provides an optional tuner AGC source, It also operates on the Q AGC block to provide a constant amplitude of 25 Hz pilot at Pin 11, and it delivers information to the pilot decoder regarding signal strength.
PILOT AND CO-CHANNEL FILTERS The Q AGC output drives a low pass `filter, made up of 4000 internal, and 430 Q and 5 KF external, From this point, an active 25 Hz band-pass filter is coupled to the Pilot Decoder, Pin 14, and another low-pass filter is connected to the Co-channel Input, Pin 12. A 2:1 reduction of 25 Hz pilot level to the Pilot Decode circuit It should be noted that i#~:@UAM@, with both chanwill cause the system to go monaural, with the comnels AM modulated, ~~,&~$oi4& increase in stereo is a ponents shown. Refer to Figure 8 for the formulas govmaximum of 3.0 d~R+:&n program material. Thereerning the active band-pass filter, The co-channel input fore, this is not th#"''pa~dFconcern in the choice of monsignal contains any low frequency intercarrier beat aural to stereo sk~~@%g point as it was in FM, and blend ~J:\>\'4...'~@,>. notes, and, at the selected level, prevents the Pilot Deis not needed>~;;;~ code circuit from going into stereo. The co-channel in~~s>::~, :,?, .$"+3, .,~f~:e put, Pin 12, gain can be adjusted by changing the ex.1>.?: ,<,, \ .~~'~,':.. ternal 1.5 k resistor. The values shown set the "trip" y $; ~>. ;,*. ., `~:, "*::.:>*,,!? PIN DESCRIPTIONS level at about 7% modulation. The 25 Hz pilot signal at ~~:;~j:,2"_ Detector Filters, Rout = 4.3 k, recommend the output of the active filter is opposite in phase to the .$) $,1,., 0.0033 pF to VCC to filter 450 kHz compo:,,. ,. pilot signal coming from the second low-~ass filter. The ,,)<., nents. 56 k resistor from-Pin 14 to Pin 12 causes the pilot to .,$: i-h.. be cancel led at the co-channel input. This allows-a more ;*...,*,> $""'''f$Pin 3 -- IF Signal Input \.$~ .:< `$' Pin 4 \.\,, \:.>ac, ZIJ,..... ..~~. to ground sets the AGC time constant. High `tc,~,, impedance output, needs buffer. THE PILOT DECODER *:$' -- Error Amp compensation to stabilize the Va The Pilot Decoder has two modes of operat[@~ Wtien Pin 5 # Gain feedback loop signal conditions are good, the decoder wil~.sm$h to -- Vcc, 6-10 Vdc, suitable for low Vbati autoPin 6 stereo after 7 consecutive cycles of the 2,5%~ibt tone. motive operation, but must be protected When signal conditions are bad, the,$~~~t,~ intetierence changes the pilot counter so as~qj~wlre 37 confrom "high line" condition. secutive cycles of pilot to go to ~$w~~n a frequency Pin 7,8 -- Left and Right Outputs, NPN emitter followers synthesized radio, the logic .tha%,m~&%the audio when Pin 9 -- Forced Monaural, MOS or TTL controllable tuning can be connected to.~ `*!When this pin is held low it-holds the decoder i~<~j~~q~rai mode and switches Pin 10 -- Lock detector filter, `Rout = 27 k, recomit to the short count. T@p@ should be held low until mend 2.2 pF to ground. Pinll -- AGCd Q output, NPN emitter follower with the synthesizer andj.~-r have both locked onto a 400 Q from emitter to Pin 11 new station. A 3~9 *+.&$&lay should be sufficient. If the Pin 12 -- Co-channel Input, 2.0 k series in and 47 k synthesizer log;@,@es''not provide sufficient delay, the feedback circuit show~~~fi~$$i~ure 9 may be added. Once Pin 9 goes high,$$~m-,~jiot Decoder starts counting. If no pilot Pin 13 -- Pilot Filter Input to op amp, see Figure 8 is detect~~~ seven consecutive counts, it is assumed Pin 14 -- Pilot Decode Input (OP amp output) emitter follower, Rout = 100 Q to b,~,$'~,+qdbd monaural station and. the decoder is Pin 15 -- Stereo Lamp, open-collector of an NPN swiah~ 10 the long count. This reduces the possibility .p~$~~stereo triggering due to signal level fluctuation common emitter stage, can sink 50 mA, .$:i.i .i)i.c.f,...-,,., Vsat = 0.3 V at 5.0 mA ~,wianolse. If the PLL goes out of lock, or interference is Pin 16 -- Ground `$;;*tected by the co-channel protection circuit before Pin 17 -- Oscillator input, Rin = 10 k, do not dc con`$:seven cycles are counted, the decoder goes into the long count mode. Each disturbance will reset the counter to nect to Pin 18 or ground zero. The Level Detector will keep the decoder from Pin 18 -- Oscillator feedback, NPN emitter, Rout = 100a going into stereo if the IF input level drops 10 dB, but will not change the operation of the pilot counter. Pin 19 -- Phase Detector Output, current source to filOnce the decoder has gone into the stereo mode, it ter will go instantly back to monaural if either the lock dePin 20 -- Detector Filter, Rout = 4.3 k, recommend tector on Pin 10 goes low, or if the carrier level drops 0,0033 pF to VCC to filter 45o kHz 4
below the preset threshold. Seven consecutive co;%ts S of no pilot will also put the decoder in monaural. [h stereo, the co-channel input is disabled, and co-channel -or other noise is detected by negative excursions of the I DET, as mentioned earlier. When these excursions reach a level caused by approximately 2070 modulati of co-channel, the lock detector puts the system in mo* aural, even though the PLL may still actually be locked. This higher level of co-channel tolerance provides the hysteresis to prevent chattering in and out of stereo on S.)* a marginal signal. When all inputs to the Pilot Decode block$~aisorrect, and it has completed its count, it turn~fo~j$~ Switch, sending the L- R to the Matrix, and $@Q#$s the pilot lamp pin to a low impedance to,~~~.~> ,v,~ ~ `~: .,.+< a ,`:~~c' .!j$h~ \.\,...:?}, ,, SUMMARY ,,:$.>.,',,:,3/ ..:~+::< ,. `
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MOrOROkA
Semiconductor Products Inc.
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FIGURE 5 -- CERAMIC VCO 5.0
20
FIGURE 6 -- L - C VCO 1 I I I
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19 lE 17 mu Rata CSA3.60M~
4.5 -%
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FIGURE 7 -- CRYSTAL VCO .~@@;E 8 - ACTIVE BAND-PASS FILTER
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3,5 >
vr~f Q
Rc=~
Rc Ra=~ Ra Rc `b `4QZRa- Rc
where, in this application: f. = center frequency = 25 Hz A. = gain at fo<25
Q<1O
Choose values for fo, Ao, Q, and convenient C, solve for resiatora
0.47 PF 0.33 PF
4.7 k 8.2 k
910 1.3 k
220 k 330 k
Note: Capacitor C should be a good grsda, low ESR.
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M070ROLA
@
Semiconductor Products Inc.
OUTLINE DIMENSIONS
Motorola reservee the right to make changes without further notice to any products herein to improve reliability, function or design. Motorola does not assume any Iiabilityarising out of the application or use of any product or circuit described herein: neither doea lt convey any license under its patent rights nor the rights of others. Motorola and @are registered trademarks of Motorola. Inc. Motorola, Inc. is an Equal Employment Opportunity/ Affirmative Action Employer.
MOTOROLA
@
Semiconductor Products Inc.
BOX 20912 .
q
PHOENIX,
ARIZONA
85036
q
A SUBSIDIARY
OF MOTOROLA
INC.
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