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MC13020
Motorola C-QUAM® AM Stereo Decoder
This circuit is a complete one ship, 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.
• 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 • Pilot Acquisition Time 300 ms for Strong Signals, Time Extended for
Noise Conditions to Prevent “Falsing”
• Internal Level Detector can be used as AGC Source
MOTOROLA C–QUAM® AM STEREO DECODER
SEMICONDUCTOR TECHNICAL DATA
20 1
P SUFFIX PLASTIC PACKAGE
CASE 738
ORDERING INFORMATION
Device
Operating Temperature Range
Package
MC13020P TA = – 40 to +85°C Plastic DIP
+8.0Vdc
Figure 1. Simplified Application
0.0033
0.0033
0.0033
220
IF Input
Optional Tuner AGC Source
0.01
+ 10µF
0.001
1 l Detector
2 Envelope Detector
3 IF Input
4 Level Detector
5 Error Amplifier
6 VCC
Q Detector Phase Detector Osc. Feedback
Osc. Input
Ground
Stereo Lamp Pilot Detector
Input
20 19 18 17
51pF 16
47µF +
430 3.3k
0.01
15 14 +
0.47
0.0033
Audio Outputs
Auto Monaural
7 Left Output
8 Right Output
100k 9 Forced Monaural
Pilot Filter Input
Co–Channel Input
220k 13 +
4.7k
56k 0.47 910
12 1.5k + 1.5k
10µF
+ 2.2µF
10 Lock + 2.2µF
AGC’d Q 11 Output
430
+ 4.7µF
*muRata Ceramic Resonator – CSA3.60MGF101
LED Stereo Indicator
The purchase of the Motorola C–QUAM® AM Stereo Decoder does not carry with such purchase any license by implication, estoppel or otherwise, under any patent rights of Motorola or others covering any combination of this decoder with other elements including use in a radio receiver. Upon application by an interested party, licenses are available from Motorola on its patents applicable to AM Stereo radio receivers.
MOTOROLA ANALOG IC DEVICE DATA
© Motorola, Inc. 1995
1
MC13020
MAXIMUM RATINGS Rating
Supply Voltage Pilot Lamp Current, Pin 15 Operating Temperature Storage Temperature Junction Temperature Power Dissipation
Derate above 25°C
Symbol VCC
TA Tstg TJ(max) PD
Value 14 50
–40 to +85 –65 to +150
150 1.25 10
Unit Vdc mAdc °C °C °C W mW/°C
ELECTRICAL CHARACTERISTICS (VCC = 8.0 Vdc, TA = 25°C, Input Signal = 200 mVrms. Unmodulated carrier, circuit of Figure 1, unless otherwise noted.)
Characteristics
Min Typ Max
Unit
Supply Line Current Drain, Pin 6
20 30 40 mAdc
Input Signal Level, Unmodulated, Pin 3, for Full Operation
112 200 357 mVrms
Audio Output Level, 50% Modulation
L only or R only 160 220 280 mVrms
Monaural 80
110 140
Channel Balance, 50% Modulation, Monaural
–
– ±1.0
dB
Output THD, 50% Modulation Output THD, 90% Modulation
Monaural Stereo
Monaural
– – –
– 0.5 – 1.0 – 1.0
%
Channel Separation, L only or R only, 50% Modulation
23 30
–
dB
Input Impedance Output Impedance
Rin 20 Cin –
–
27 – 6.0 –
100 150
kΩ pF
Ω
Pilot Acquisition Time VCO locked (after release of forced monaural) Bad Signal Condition
– 280 300
1.48 –
–
ms sec
Lock Detector Filter Voltage, Pin 10
In Lock 7.7
8.0
–
Out of Lock –
0.8 1.0
Vdc
Force to Monaural, Pin 9 Pull–Down for Monaural Mode
2.0 2.5
–
– 0.15 1.0
Vdc µA
Pull–Up for Automatic Mode
– 3.5 3.7 – <0.001 1.0
Vdc µA
Figure 2. Basic Quadrature AM (QUAM)
1+L+R
Average Carrier θ
(1+L+R)2 + (L–R)2 = Envelope
Envelope amplitude is not a correct sum signal for envelope detection. L–R
Figure 3. Motorola C–QUAM®
(1+L+R)cosθ 1+L+R
Average θ Carrier
Envelope is compatible with existing monaural receivers.
(L–R)cosθ
2 MOTOROLA ANALOG IC DEVICE DATA
MC13020
Figure 4. Representative Block Diagram
VCC
10µF
2.2µF
0.0033
0.0033
0.001
0.0033
++
62
15
20
4 10
Optional AGC
To Tuner
0.01
IF Input
3
Env 1+L+R DET
1/cosθ
Var Gain
Phase DET
VCO
19 18
+ C1
Crystal
17
See Text and Figures
R2
C2
5, 6 and 7
Rd CS 0.01
Error Amp
Level DET
Matrix
IDET 0°
90° Divide by 8
16
1+L+R
Lock
Q L–R DET
Pilot Decode
Switch
Q
AGC
++
400 –
– 2.0k 47k
14
11 13 220k 56k 12
430 0.47 + 4.7k
+ 0.47 1.5k
7 L Audio
8
R
Outputs (Note 1)
VCC
220
LED Stereo 15 Indicator
9 Force to Monaural
+ 1.5k + 4.7µF
2.2µF
+ 10µF 910
NOTE 1. Output polarity is defined for receiver front end with LO above signal frequency.
MOTOROLA C–QUAM® – COMPATIBLE QUADRATURE AM STEREO
Introduction In C–QUAM®, conventional quadrature amplitude
modulation has been modified by multiplying each axis by cosθ as shown in Figures 2 and 3. The resulting carrier envelope is 1 + L + R, i.e., a correct sum signal for monaural receivers and for stereo receivers operating in monaural mode. A 25 Hz pilot signal is added to the L – R information at a 4% modulation level.
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.