TELEFUNKEN Semiconductors
U4311B
Rev. A1: 23.06.1995
1 (14)
LowCurrent Superhet Remote Control Receiver
Description
The U4311B is a monolithic Integrated Circuit in bipolar
technology for low-current UHF remote control super-
heterodyne receivers in amplitude- or frequency-
modulated mode. Typical applications are keyless car
lock-, alarm or telecontrol remote indication systems.
Especially for automotive applications it supports a
superhet design with about 1 mA total current consump-
tion, as required by the car manufacturers.
Features
D Usable for amplitude- and frequency- modulated
transmission systems
D Extremely low quiescent current approximately 1 mA
in the stand-by mode due to wake-up concept
D Wide power supply voltage range 3 to 13 V
D Sensitive IF-amplifier for 10.7 MHz operating
frequency
D Logarithmic AM demodulator
D FM demodulator
D Monoflop exit to wake up a microcontroller
D High performance operational amplifier to realize a
data recovering filter
D Non-inverting clamping comparator with amplitude-
depending hysteresis for data regeneration
Block Diagram
Non invert.
clamping
comparator
Monoflop
Bandgap
Quadrature
detector
Operational
amplifier
IF
amplifier
Internal
RF
Level
Wake up
10
3
Wake up out
7
6
V
S
2
5
+
16
1
14
12
8
Data out
Data
filter
FM out
log AM out
10.7 MHz
10.7 MHz
13
11
V
Ref
= 2.4V
4
95 9968
V
Ref
= 2.4 V
9
Figure 1. Block diagram
TELEFUNKEN Semiconductors
U4311B
Rev. A1: 23.06.1995
2 (14)
Pin Description
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
RC
wake
GND2
95 10322
Comp
out
RC
RC+
AM
out
OP
in+
OP
out
FM
out
V
Ref
Discr
GND1
SW
out
IF
in
OP
in
V
S
Figure 2. Pin description
Pin
Symbol
Function
1
OP
in+
OP amplifier non inverted input
2
OP
out
OP amplifier output
3
RC
wake
RC wake up reset time
4
GND2
Ground of the logical circuits
5
Comp
out
Comparator output
6
RC
Comparator time constant
7
RC+
Comparator time constant
8
AM
out
AM current output
9
IF
in
IF input
10
SW
out
Wake up output
11
GND1
Ground of the analog circuits
12
Discr
FM discriminator tank
13
V
ref
Reference voltage
14
FM
out
FM discriminator output
15
V
S
Supply voltage
16
OP
in
OP amplifier inverted input
Internal connections see figures 4 to 19
Absolute Maximum Ratings
Parameters
Symbol
Value
Unit
Supply voltage
V
S
13
V
Power dissipation
T
amb
= 85
C
P
tot
400
mW
Junction temperature
T
j
125
C
Ambient temperature
T
amb
40 to +85
C
Storage temperature
T
stg
55 to +125
C
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient
DIP16
SO16L
R
thJA
R
thJA
120
100
K/W
K/W
TELEFUNKEN Semiconductors
U4311B
Rev. A1: 23.06.1995
3 (14)
Electrical Characteristics
V
S
= 5 V, T
amb
= 25
C, f
in
= 10.7 MHz; FM part: f
mod
= 1 kHz, f
dev
= 22.5 kHz; AM part: f
mod
= 1 kHz, m = 100%
unless otherwise specified
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Characteristics
Supply voltage range
Pin 15
V
S
3
12
V
Quiescent supply current
Pin 15
I
q
1
1.3
mA
Active supply current
Pin 15
I
act
2.8
3.6
mA
Bandgap
Regulated voltage
Pin 13
V
ref
2.3
2.4
2.5
V
Output current
Pin 13
I
ref
5
mA
Source resistance
Pin 13
R
ref
2.3
5
W
External capacitor
Pin 13
C
ref
10
mF
Power supply rejection
ratio
f = 50 Hz
Pin 13
psrr
60
dB
IF amplifier
Input resistance
Pin 9
R
in
180
330
520
W
Input capacitance
Pin 9
C
in
5
pF
Typical internal 3 dB
frequency
IF level 70 dB
mV
Pins 9 and 14
f
3dB
8
12
MHz
3 dB limiting point
Pin 9
V
FM3dB
30
dB
mV
Recovered data voltage
Pin 14
V
FMout
50
130
230
mV
FM detector output resis-
tance
Pin 14
R
FMout
50
k
W
AM rejection ratio
m = 30%
Pins 9 and 14
AM
rr
25
dB
Maximum AM input
voltage
Pin 9
V
AMmax
90
dB
mV
AM quiescent current
Pin 8
I
AMout
10
22
37
mA
Maximum AM current
Pin 8
I
AMoutmax
100
mA
Operational amplifier
Gain bandwidth product
Pins 1, 2 and 16
f
t
3
4
6.5
MHz
Excess phase
Pins 1, 2 and 16
d
80
degree
Open loop gain
Pins 1, 2 and 16
g
0
50
70
95
dB
Output voltage range
Pin 2
V
out
1.55
V
Common mode input
voltage
Pins 1 and 16
V
in
0.7
1.7
V
Input offset voltage
Pins 1 and 16
V
os
2.5
0
+2.5
mV
Maximum output current
Pin 2
I
out
5
mA
Common mode rejection
ratio
Pin 1 and 16
cmrr
65
85
dB
Total harmonic distortion
V
in
< 300 mV, f = 33 kHz,
unity gain circuit Pin 2
thd
1
3
%
Power supply rejection
ratio
f = 50 Hz
Pin 2
psrr
65
85
dB
TELEFUNKEN Semiconductors
U4311B
Rev. A1: 23.06.1995
4 (14)
Unit
Max.
Typ.
Min.
Symbol
Test Conditions / Pins
Parameters
Clamping comparator
Typical common mode
input voltage range
Pin 2
V
cmvr
0.8
1.6
V
Maximum distortion
voltage
V
signal
= 100 mV,
R+ = R = 50 k
W,
C+ = C = 200 nF,
f
disto
= 50 Hz,
f
signal
= 1 kHz
Pin 2
V
dmax
200
mV
Output voltage
V
2
> (V
6
+ V
7
) /2
(10 k
W load to V
Ref
)
Pin 5
V
cout
V
Ref
1)
Output voltage
V
2
< (V
6
+ V
7
) /2
(10 k
W load to V
Ref
)
Pin 5
V
cout
0
150
250
mV
Wake up circuit
Minimum wake up level
Pin 9
V
in
40
dB
mV
2)
Internal charging resistor
Pin 3
R
int
1.5
k
W
Threshold voltage
Pin 3
V
th
1.6
V
Output switch current
Pin 10
I
SW
180
250
550
mA
Output switch voltage
Pin 10
V
SW
5.5
V
3)
External wake up resistor
Pins 3 and 13
R
WU
22
k
W
External wake up capacitor
Pins 3 and 13
C
WU
10
mF
Hold time (
30%)
t
h
1.5 R
WU
C
WU
s
4)
Delay time (
30%)
t
d
C
WU
0.75 kW
s
4)
1)
IC version with inverting comparator available: U4313B
2)
Measured at Pin 9, referred to 330
W
3)
Protected by a Z-diode, see figure 13
4)
Valid for 0.1
mF
C
WU
10
mF and 22 kW
R
WU
680 k
W
Application
The U4311B is well-suited to implement UHF remote
control or data transmission systems, based on a low-
current superheterodyne receiver concept. SAW-devices
may be used in the transmitter as well as in the receiver
local oscillator. The front end should be a discrete circuit
application with low current UHF-transistors like S822T
or S852T from TEMIC TELEFUNKEN microelectronic
GmbH. The frequency of the local oscillator can be deter-
mined either by coaxial resonators or SAW-devices. Due
to large SAW-resonator tolerance an IF-bandwidth
* and
in a FM-system additionally the discriminator amplitude
characteristic (figure 28)
* of 300 kHz or higher is
proposed. As the circuit needs only 3.0 V supply voltage
for operation the front end may be a stacked design in
order to achieve a total receiver current consumption of
approximately 1 mA. Figure 29 shows a principle
receiver concept diagram. The application notes
ANT012, ANT013, and ANT015 contain more detailed
information on complete RF links.
TELEFUNKEN Semiconductors
U4311B
Rev. A1: 23.06.1995
5 (14)
Circuit Description
General functions
The integrated circuit U4311B includes the following
functions: IF-amplifier, FM-demodulator, wake-up
circuit with monoflop, operational-amplifier, non-
inverting data comparator and voltage-regulator.
The 10.7 MHz IF-signal from the front end passes the
integrated IF-amplifier which operates for amplitude- or
frequency-modulated signals to either a logarithmic AM-
demodulator which was implemented to avoid settling
time problems effected by use of an automatic gain
control system or a quadrature detector for FM. A data
shaping filter
* advantageously realized with the
internal high performance operational-amplifier
*
reduces system bandwidth to an optimized compromise
regarding transmission distance and data recognition.
Thus, an optimal bit error rate can be achieved without
any further active component.
The comparator connected to the output of the filter has
a level-dependent hysteresis and clamps its reference
voltage to the signal minimum and maximum peaks as
described later.
Without IF-input signal
* in the normal mode * only the
IF-amplifier and the AM demodulator which operates as
a level strength indicator are activated. If the level of the
IF signal increases, the whole circuitry is turned on by the
wake-up circuit. This signal is externally available at
pin 10 and can be used to wake up a microcontroller.
After an adjustable reset time, determined by the mono-
flop time constant, the integrated circuit rests down to the
sleep mode. In this case typically 1 mA supply current is
required. An external resistor matched at pin 3 to ground
blocks the wake-up circuit and gives fully function at
lower IF-level as to recognize in figures 24 and 27, but
supply current increases up to typically 2.8 mA.
Function of the clamping comparator
The output signal of the operational amplifier is fed to the
input of the non-inverting comparator and two peak
detectors (Q1 and Q2, figure 3). Their time constants are
distinguished by RC+ and RC. The components value
must be adapted to the transmission code. The time
constant should be large compared to the bit-rate for opti-
mized noise and hum suppression. To compensate the
input transistors base-emitter-voltage differences these
two signals are buffered by Q3 and Q4. The mean value
is used as comparator threshold, the difference of the peak
values controls the hysteresis. This clamping comparator
works as a data regenerator.
Another version of the IC, with an inverting clamping
comparator, is also available (U4313B). Therefore the
operational amplifier can be used either as a non-
inverting or an inverting filter without the need of any
additional components.
1
2
3
4
5
6
7
8
Hysteresis
Comp. threshold
Comparator
Op. amp.
+
Q1
Q3
Q4
Q2
V
Ref
to pin 16
95 9969
Figure 3. Principle function of the clamping comparator
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