TELEFUNKEN Semiconductors
U4240B
Rev. A1: 12.07.1995
1 (8)
AM-Receiver
Description
The U4240B is a bipolar integrated AM receiver circuit.
It performs all the active functions and part of the filtering
required of the AM radio receiver. The device is designed
for car radio and home receiver applications.
Features
D ESD protected
D IF output for stereo demodulator and
stop signal generation
D AF preamplifier with simple filtering
D Controlled RF preamplifier
D Double balanced mixer
D Separate oscillator with amplitude control
D IF amplifier with gain control
D Balanced full-wave detector
D Audio preamplifier
D Internal AGC voltage
D Amplifier for field-strength indication
D Electronic standby ON/ OFF switch
Block Diagram
50
W
preamplifier
Balanced
Standby
IF amplifier
full-wave
amplifier
amplifier
Controlled
AM-antenna
tank
AM-oscillator
tank
IF BPF
mixer
switch
Controlled
Balanced
detector
Control
voltage
AF
RF
Internal
supply
voltage
Controlled
oscillator
AM-IF
output
driver
Indicator
5 (6)
6 (7)
7 (8)
8 (9)
9 (11)
4 (5)
3 (4)
2 (2)
1 (1)
18 (20)
17 (19)
16 (17)
14 (15)
13 (14) 12 (13)
11 (12)
10 (11)
15 (16)
GND
V
S
5 k
W
5 k
W
7 k
W
7 k
W
3.5 k
W
12 k
W
170
W
150
W
93 7715 e
( ) SSO 20
Figure 1.
TELEFUNKEN Semiconductors
U4240B
Rev. A1: 12.07.1995
2 (8)
Pin Description
18
10
1
2
3
4
5
6
7
8
9
11
12
13
14
15
16
17
U4240B
93 7721 e
DIP 18
DIP 20
Function
1
1
Mixer output
2
2
Standby switch
3
4
IF amplifier input
4
5
V
REF
5
6
Low pass filtering
6
7
AF output
7, 8
8, 9
AGC time constant
9
10
Low pass filtered AF output
10
11
IF output
11
12
Field strength indicator
12
13
Oscillator output
13
14
Oscillator tank reference output
14
15
Oscillator tank input
15
16
V
S
16, 17
17, 19
RF input
18
20
GND
3, 18
Not connected
Controlled RF Preamplifier, Pin 7
The RF preamplifier is built up differentially in order to
achieve the best possible large signal handling capability.
Special care was taken to reduce the input stage noise.
Balanced Mixer, Pin 1
The mixer is a double balanced type with a single ended
output.
Controlled Oscillator, Pins 13 and 14
The oscillator employs temperature compensation,
simple varicap and coil connection. The amplitude of the
oscillator is controlled to low values, in order to support
AM varactor diodes. The LO-buffer supports the
U428xBM PLL-family.
Controlled IF Amplifier, Pin 3
The IF amplifier consists of two controlled gain cells
coupled by capacitive means. Internal band pass filtering
reduces higher order products and THD.
AM-IF Output, Pin 10
For AM stereo application and for stop signal generation
by IF counting Pin 10 provides a non limited but ampli-
tude controlled IF signal of about 280 mV.
Balanced Full-Wave Detector, Pin 5
The detector consists of a Gilbert cell that multiplies the
limited carrier signal with the IF output signal and there-
fore employs a full wave rectification. Second or higher
order products at the output are internally low pass
filtered.
AF Amplifier, Pin 6
The AF amplifier has two different outputs. They provide
different output resistances for simplifying applications.
For a high end application Pin 6 provides a 3.5 k
W output
resistor to support a second order low pass filter. Pin 9
provides additional 12 k
W for a simple first order low pass
filter.
AGC, Pin 8
The AGC block generates the AGC voltage that is to be
smoothed at Pin 8. The capacitor at Pin 8 defines the time
constant. The voltage at Pin 8 is buffered to control the
internal gain stages with different delay. The control volt-
age is available at Pin 11 (field strength indication).
Standby Switch, Pin 2
The whole circuit can be powered down by the standby
switch. This mode can be achieved by a dc voltage higher
than 3.5 V at Pin 2.
TELEFUNKEN Semiconductors
U4240B
Rev. A1: 12.07.1995
3 (8)
Absolute Maximum Ratings
Reference point Pin 18, unless otherwise specified
Parameters
Symbol
Value
Unit
Supply voltage
Pin 15
V
S
12
V
Input voltage
Pin 2
Pins 16 and 17
Pins 16 and 17
V
2
IV
1617
I
V
16,
V
17
12
12
VS
V
Input current
Pins 16 and 17
I
16,
I
17
200
mA
Ambient temperature range
T
amb
30 to +85
C
Storage temperature range
T
stg
55 to +150
C
Junction temperature
T
j
125
C
Electrostatic handling
(MIL Standard 883 C) except Pin 10
V
ESD
2000
V
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient
R
thJA
100
K/W
Electrical Characteristics
V
S
= 8.5 V, reference point Pin 18, f
iRF
= 1 MHz, R
G
= 50
W, f
mod
= 0.4 kHz, m = 30%, f
IF
= 460
kHz, T
amb
= 25
C,
unless otherwise specified
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Supply
Pin 15
Supply voltage
V
S
7.5
12
V
Supply current
without load:
I
L
= 0 (Pin 13)
I
S
23
30
mA
RF preamplifier
DC input voltages
Pins 16 and 17
V
i
V
S
/2
V
Input impedance
V
iRF
< 300
mV, Pins 16, 17
V
iRF
> 10 mV Pins 16, 17
R
i
C
i
R
i
C
i
5.5
25
80
22
k
W
pF
k
W
pF
Maximum RF input voltage
Pins 16 and 17
V
i
2.5
V
pp
Mixer output
Pin 1
Output impedance
R
o
C
o
500
6.0
k
W
pF
Conversion conductance
I
oIF
/V
iRF
s
M
6.5
mA/V
Oscillator
Frequency range
Pin 14
f
osc
0.6
60
MHz
Oscillator circuit
impedance range
Pin 14
Z
Losc
0.5
200
k
W
Controlled oscillator
amplitude
Pin 14
V
osc
130
160
mV
DC output voltage
I
L
= 0
Pin 13
V
o
6 V
BE
(4.2V)
V
Output load current range
Pin 13
I
l
0
20
mA
TELEFUNKEN Semiconductors
U4240B
Rev. A1: 12.07.1995
4 (8)
Unit
Max.
Typ.
Min.
Symbol
Test Conditions / Pins
Parameters
Oscillator frequency output, R
L10
= 2.2 k
W
Pin 12
Output voltage
V
O
320
mV
pp
DC output voltage
V
O
0.9
V
Output resistance
R
O
170
W
Output current
I
O
3
mA
p
IF amplifier and demodulator
DC input voltages
Pins 3 and 4
V
i
2
V
Input impedance
Pins 3
R
i
C
i
2.4
3
7
3.9
k
W
pF
Maximum IF input voltage
m = 80%, d = 3%,
Pin 3
V
i
55
mV
IF output voltage,
without load
V
i
= 10 mV (Pin 3/4)
Pin 10
V
o
230
280
340
mV
IF output resistance
Pin 10
R
o
50
W
Control range
DV
oAF
= 6 dB
DV
i
50
dB
Audio output voltage,
without load
V
i
= 1 mV
(Pin 3/4)
Pins 6 and 9
V
o
310
mV
Audio output resistance
Pin 6
Pin 9
R
o
2.9
9
3.5
12
4.2
15
k
W
Field strength indication
Pin 11
DC indicator voltages
R
L11
= 2.7 k
W, V
i
= 0
R
L11
= 2.7 k
W,
V
i
= 500 mV
V
o
2.5
100
2.8
3.1
mV
V
Output current capability
I
o
2.0
mA
Output resistance
I
o
= 0.5 mA
R
o
150
W
Reverse voltage at the
output
AM switch OFF,
"I
o
x 1 mA
V
o
6
V
Standby switch
Pin 2
Switching voltage
V
I
4 V
BE
(2.75)
V
Required control voltage
AM-ON
AM-OFF
V
I
V
I
1)
3.5
2
V
Input current
AM-ON, V
2
= 0
AM-OFF, V
2
= 12 V
1)
I
I
"I
I
200
10
mA
1)
or open input
TELEFUNKEN Semiconductors
U4240B
Rev. A1: 12.07.1995
5 (8)
Operating Conditions
V
S
= 8.5 V, f
iRF
= 1 MHz, f
mod
= 0.4 kHz, m = 30%, T
amb
= 25
C, reference point Pin 18 (fig. 2) unless otherwise specified
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
RF input voltage
(S+N)/N = 6 dB = 26 dB
= 46 dB
V
iRF
1.5
15
150
mV
RF input for AGC operation
V
iRF
30
mV
Control range with ref. to
V
iRF
= 500 mV
DV
oAF
= 6 dB
DV
iRF
87
dB
Maximum RF input voltage
d = 3%, m = 80%
d = 3%, m = 30%
d = 10%, m = 30%
V
iRF
0.5
0.7
0.9
V
Audio output voltage
V
i
= 1 mV
Pin 6
V
i
= 4
mV, m = 0.8
V
oAF
310
75
mV
RF input voltage
V
oAF
= 60 mV
V
iRF
2
5.5
9
mV
Total distortion of audio
output voltage
m = 80%, V
i
= 1 mV
m = 30%, V
i
= 500 mV
d
0.7
0.9
%
%
Signal plus noise to noise
ratio of audio output voltage
V
i
= 100 mV
(S+N)/N
56
dB
IF bandwidth ( 3 dB)
B
IF
4.6
kHz
IF selectivity
Df = "9 kHz
Df = "36 kHz
S
IF
30
60
dB
Test Circuit
14
22
1
L
95
mH
33 pF
Band
switch diodes
2...22 pF
R
L12
2.2 k
W
10 nF
13
12
0.1
mF
11
R
L11
2.7 k
W
1 mA
fosc
voIF
10
507 pF
12...440 pF
22
VS1
S2
V
50
16
15
0.1
mF
17
18
viRF
22 nF
1
3.9 nF
L2
3
L
2.2 k
W
56 pF
IF Filter
SFZ
460 A
S2
V
AM
2
3
4
5
6
10 nF
3.3 nF
voAF
2.2
mF
3.3 nF
voAF
7
8
9
C7
22
mF
C8
0.1
mF
U4240B
93 7617 e
0.22
mF
47
mF
+
R
G
12 k
W
W
W
W
Figure 2.
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