U4488B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A2, 15-Jan-98
1 (9)
Quasi-Split Sound Circuit and AM Demodulator
Description
The U4488B is an integrated bipolar circuit for full multi-
standard sound IF signal processing in TV/VTR and
Multimedia applications. It supplies AM signals as well
as FM/NICAM sound IF signals and thus allows the de-
sign of a universal sound IF module for various
applications. The U4488B has the same performance like
the U4468B, with the additional feature of a second sym-
metrical IF input.
Features
D 5-V supply voltage; low power consumption
D Gain-controlled 3-stage wideband IF amplifier
D Active carrier generation by FPLL principle
(frequency-phase-locked-loop) for true quadrature
demodulation
D Complete alignment-free AM demodulator
D Switchable amplitude detector for gain control, which
operates as a peak detector for FM sound and as a
mean level detector for AM sound
D Two symmetrical IF inputs
Block Diagram
Mean
FPLL
VCO
8
9
12
AM-Det
6
Peak
level
IF-Amp
1
2
REF
14
4
V
S
5
Loop
filter
VCO
7
13
10
3
IF AGC
Mean/peak
S1
S2
Mute
Intercarrier
(FM)
AF(AM)
AGC
IF
FM
IF
AM
13789
15
16
IF-Switch
11
S3
IF1/IF2
0
90
Figure 1. Block diagram
Ordering Information
Extended Type Number
Package
Remarks
U4488B
DIP16
U4488B
TELEFUNKEN Semiconductors
Rev. A2, 15-Jan-98
Preliminary Information
2 (9)
Circuit Description
IF Amplifier and AGC
The symmetrical IF input signal from the external SAW
filter is fed to the Pins 1 and 2 resp. Pins 15 and 16. For
FM/NICAM application, a SAW filter with double
bandpass characteristic is required for the vision and
sound carrier. In case of L-standard, a bandpass filter with
the center frequency at the L-sound carrier is used.
The amplifier consists of three AC-coupled wideband IF
stages. Each differential amplifier stage is gain controlled
by the AGC (Automatic Gain Control) voltage, available
at Pin 3. The output signal of the IF amplifier is then
applied to the FPLL carrier generation, to the mixer for
FM/NICAM signals and to the AM demodulator.
The IF-AGC is derived from the average level of the AM
carrier (L standard) or from the peak value of the FM
carrier (e.g., B/G standard). It controls the three-stage
wideband amplifier to provide a constant SIF signal to the
AM demodulator or to the QSS (quasi-split sound) mixer.
IF Input Switch
If Pin 11 is open, the IF input 1 is switched on (Pins 1
and 2). If Pin 11 is connected to ground, the IF input 2 is
switched on (Pins 15 and 16).
Standard Switch
If the standard switch (Pin 7) is in position `low' (for AM
sound), the AGC is operating as an average level detector.
In position `open' or `high' (for FM/NICAM sound), the
AGC is a peak value detector.
Internal Voltage Stabilizer
The internal bandgap reference voltage (4.25 V at Pin 4)
ensures constant performance, independent of supply
voltage and temperature.
FPLL, VCO
The FPLL (frequency-phase-locked loop) circuit consists
of a frequency detector and a phase detector to generate
a control voltage for the VCO tuning. In locked mode the
VCO is controlled by the phase detector while in
unlocked mode, the frequency detector is superimposed.
The VCO operates with an external resonance circuit
(L
and C parallel) and is controlled by integrated
varicaps.
A practicable VCO alignment of the external coil is the
adjustment of the loop filter voltage (Pin 5) to 2.3 V. At
this value, capture and hold range are centered.
AM Demodulator
The alignment-free AM demodulator is realized by a
synchronous detector. The modulated IF signal from the
wideband IF amplifier output is multiplied in phase with
the limited SIF signal to remove the AM. Then, the
resulting AF signal of the demodulator output is fed to the
output amplifier and to the AGC stage.
Quasi-Split-Sound (QSS) Mixer
The QSS mixer is realized by a multiplier circuit. The IF
signal (FM/NICAM) is converted in the intercarrier
frequency by means of a quadrature signal from the
generated picture carrier provided by the PLL. The
intercarrier signal is fed via an output amplifier to Pin 12.
Mute Switch
AM sound output (Pin 6) can be muted in pulling mute
switch (Pin 10) to `low'.
U4488B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A2, 15-Jan-98
3 (9)
Pin Description
Pin
Symbol
Function
1, 2
V
i1, IF
IF input 1 (symmetrical)
3
C
AGC
Capacitor for AGC time constant
4
C
REF
Capacitor for internal reference
voltage
5
LF
Loop filter
6
V
o,AM
AF output (AM sound)
7
V
sw,AGC
Standard switch
8, 9
V
VCO
VCO circuit
10
V
sw,mute
Mute switch
11
V
sw, IF
IF input switch IF1 / IF2
12
V
o,FM
Intercarrier output (FM sound)
13
GND
Ground
14
V
S
Supply voltage (5 V)
15, 16
V
i2, IF
IF input 2 (symmetrical)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
U4488B
V
i1,IF
V
i1,IF
C
AGC
C
REF
LF
V
o,AM
V
sw,AGC
V
VCO
V
S
GND
V
o,FM
V
sw,mute
V
VCO
13791
V
i2,IF
V
i2,IF
V
sw,IF
Figure 2. Pinning
Absolute Maximum Ratings
Reference point Pin 13, unless otherwise specified
Parameters
Symbol
Value
Unit
Supply voltage range
Pin 14
V
S
4.5 to 9.0
V
Supply current
Pin 14
I
S
55
mA
Power dissipation (V
S
= 9 V)
P
500
mW
Output currents
Pins 6 and 12
I
out
5
mA
External voltages
Pins 1, 2, 3, 4, 6, 12, 15 and 16
+ 4.5
V
Pins 5, 8 and 9
V
ext
+ 3.5
V
Pins 7, 10 and 11
V
S
V
Junction temperature
T
j
+125
C
Operating temperature range
T
amb
0 to +85
C
Storage temperature
T
stg
25 to +125
C
Electrostatic handling *
all pins
V
ESD
" 300
V
*) Equivalent to discharging a 200-pF capacitor through a 0-
W resistor
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient when soldered to PCB
R
thJA
60
K/W
U4488B
TELEFUNKEN Semiconductors
Rev. A2, 15-Jan-98
Preliminary Information
4 (9)
Electrical Characteristics
V
S
= + 5 V, T
amb
= + 25
C; reference point Pin 13, unless otherwise specified
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
DC-supply
(Pin 14)
Supply voltage
V
S
4.5
5.0
9.0
V
Supply current
v
in
=10 mV or V
3
= 2 V
I
S
40
mA
IF-input
(Pins 1 and 2 resp. 15 and 16)
Minimum IF input signal
Output signal: 3 dB
v
in
50
V
rms
Maximum IF input signal
Output signal: +1 dB
v
in
70
100
mV
rms
Input impedance
(See note 1)
R
in
1.2
k
W
Input capacitance
(See note 1)
C
in
2
pF
IF input switch
(Pin 11)
Switching voltage: IF input 1
Inputs: Pins 1 and 2
V
swIF1
open
Switching voltage: IF input 2
Inputs: Pins 15 and 16
V
swIF2
0
1.5
V
Switching current
I
sw
50
A
SIF-AGC
(Pin 3)
IF gain control range
G
v
60
65
dB
AGC capacitor
C
AGC
4.7
F
FPLL and VCO
(Pins 5, 8 and 9)
Max. oscillator frequency
For carrier generation
f
VCO
70
MHz
Vision carrier capture range
f
vco
= 38.9 MHz
C
vco
= 6.2 pF
Df
cap
"1.5
"2
MHz
Oscillator drift (free runing)
as function of temperature
DT
amb
=
55
C,
f
vco
= 38.9 MHz
C
vco
= 6.2 pF,(see note 2)
Df/D
T
0.3
%
Standard switch
(Pin 7)
Switching voltage for mode 1:
FM/NICAM sound
Peak value control
(see note 3)
V
sw1
2.0
V
S
V
Switching voltage for mode 2:
AM sound
Average level control
V
sw2
0
1.5
V
Switching current
I
sw
"100
mA
AM mute switch
(Pin 10)
Switching voltage
AM output active
V
mute1
open
Switching voltage
AM output switched off
V
mute2
0
1.5
V
Switching current
I
mute
100
mA
Notes
1.
This parameter is given as an application information and not tested during production
2.
The oscillator drift is related to the picture carrier frequency, with external temperature compensated LC circuit
3.
Without external control voltage (Pin 7 open), the IC automatically operates in mode 1
U4488B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A2, 15-Jan-98
5 (9)
Electrical Characteristics (continued)
V
S
= + 5 V, T
amb
= + 25
C; reference point Pin 13, unless otherwise specified
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Intercarrier output
(Pin 12)
(see note 4)
DC output voltage
V
DC
2
V
Output resistance
(See note 1)
R
out
200
W
Intercarrier output signal
v
in
= 10 mV
5.5 MHz output signal
V
out
100
150
mV
rms
Intercarrier bandwidth
1 dB
3 dB
B
tbd
tbd
MHz
MHz
Weighted signal-to-noise ratio
(CCIR 468)
B/G mod. VIF signal:
v
in
= 10 mV;
FM dev. =
27 kHz;
f
mod
= 1 kHz;
tested with U2860B;
Black screen: Channel 1/2
Color bar: Channel 1/2
60/58
58/56
dB
dB
Ripple rejection
Tested from Pin 14 to 12
(see note 1)
RR
35
dB
Allowable AC output peak
current
I
AC
" 0.7
mA
Allowable DC output current
I
DC
2
mA
AF output AM
(Pin 6)
(see note 5)
DC output voltage
V
DC
2.2
V
Output resistance
(See note 1)
R
out
150
W
AF output signal
m = 54%
v
oAF
500
mV
rms
AF bandwidth
3 dB
B
tbd
kHz
Total harmonic distortion
m = 54%
f
mod
= 1 kHz, 12.5 kHz
THD
1
2
%
Weighted signal-to -oise ratio
(CCIR 468)
Reference: m = 54%;
f
mod
= 1 kHz
S/N
56
dB
Ripple rejection
Tested from Pin 14 to 6
(see note 1)
RR
28
dB
Allowable AC output peak
current
I
AC
" 0.3
mA
Allowable DC output current
I
DC
1
mA
Notes
1.
This parameter is given as an application information and is not tested during production
2.
The oscillator drift is related to the picture carrier frequency, with external temperature compensated LC circuit
3.
Without external control voltage (Pin 7 open), the IC automatically operates in mode 1
4.
Picture carrier PC = 38.9 MHz; sound carrier SC
1
= 33.4 MHz, SC
2
= 33.16 MHz;
PC/SC
1
=13 dB; PC/SC
2
= 20 dB; PC unmodulated (equivalent to sync peak level)
5.
Sound carrier SC = 32.4 MHz, modulated with f
mod
= 1 kHz, m = 54%; v
in
= 10 mV
PDF 
ZIP