ATMEL ATR4253

Features
• Highly Integrated - All-in-one Active Antenna IC
• Operating Frequency Range: 50 to 900MHz
•
•
•
•
•
•
•
•
•
•
– Main Application 76 to 108MHz (Broadcast FM Worldwide)
Integrated AGC
Integrated Driver for PIN Diodes
Integrated Power Supply Regulator
Integrated Antenna Sensor
High Dynamic Range
Excellent Noise Performance
High Intercept Point 3rd Order
RF Amplifier Adjustable to Various Cable Impedances
Low Noise Output Voltage
Low Power Consumption
Integrated
Circuit Solution
for Active
Antennas
1. Description
The Atmel® ATR4253 is a highly integrated high-performance IC for active antenna
amplification. The device has a built-in AGC, antenna detection, a power supply regulator and two driver stages for external PIN diodes.
Atmel ATR4253
The Atmel ATR4253 is based on BICMOS technology. The device is designed in particular for car applications and is suitable for active antennas located in several
positions within the car such as bumpers, windscreen, mirrors or windows.
Summary
Figure 1-1.
Block Diagram
RFB
RFE
PD2
RFC
12
11
10
9
FM
Amplifier
BIAS
13
GND2
14
REF
15
PD1
16
Voltage
Supply
AGC
(FM)
Antenna
Detection
1
Over
Voltage
2
3
4
ANTENNA VSTART OVDET VREGO
SENSE
8
DET
7
TC
6
VS
5
GND1
NOTE: This is a summary document.
The complete document is available
under NDA. For more information,
please contact your local Atmel sales
office.
9194CS–AUDR–10/10
2. Pin Configuration
Table 2-1.
2
2
OVDET
3
VREGO
4
REF
GND2
BIAS
15
14
13
Atmel
ATR4253
5
6
7
8
DET
VSTART
16
TC
1
VS
ANT SENSE
PD1
Pinning VQFN 3x3 / 16 Pins
GND1
Figure 2-1.
12
RFB
11
RFE
10
PD2
9
RFC
Pin Description
Pin
Symbol
1
ANT SENSE
Function
2
VSTART
Comparator input of voltage detector
3
OVDET
Overvoltage detection input
4
VREGO
Voltage regulator output
5
GND1
Ground voltage regulator
6
VS
Supply voltage
7
TC
AGC time constant
Antenna sense input
8
DET
AGC level detector input
9
RFC
Amplifier Collector (NPN)
10
PD2
2nd AGC output for pin diode
11
RFE
Amplifier emitter (NPN)
12
RFB
Amplifier base (NPN)
13
BIAS
Bias voltage (2.7V)
14
GND2
Ground FM
15
REF
Reference voltage (6V)
16
PD1
1st FM AGC output for pin diode
Paddle
GND
Ground paddle
Atmel ATR4253
9194CS–AUDR–10/10
Atmel ATR4253
3. Functional Description
The Atmel® ATR4253 is a highly integrated antenna amplifier with a broad range of features
and functions. It compensates cable losses between the antenna and the car radio, which is
usually placed far away from the antenna. The device can be used in the frequency range of
50 up to 900MHz (i.e. FM, DAB (+), DMB, DVB-T, ISDB-T, etc.) and has the flexibility to
address different antenna types (e.g., glass, windscreen, roof antennas).
A separate automatic gain control (AGC) function is integrated in order to avoid overdriving the
RF amplifier at large signal conditions.
The integrated PIN diode drivers help to reduce the external component cost and to minimize
the board space.
The external component cost can be further reduced as the voltage regulation stage is also
integrated. This stage provides overvoltage protection and current limitation. An external transistor is used as power driver for this stage.
3.1
RF Amplifier Stage
The RF amplifier is realized with a high-performance NPN transistor. This allows the use of an
amplifier configuration which is optimized for the individual application requirements. For
low-cost applications, the common emitter configuration enables good performance at reasonable BOM cost. For high-end applications, a common base configuration with transformer
feedback provides high IP3 and low noise figures at reasonable current consumption. In both
configurations, gain, input and output impedance can be adjusted by modifying the external
components.
The bias voltage (BIAS) for the base of the NPN transistor is derived from an integrated voltage reference and has a PTAT (proportional to absolute temperature) behavior. The bias
current of the RF amplifier is defined by an external resistor and is kept constant over
temperature.
3.2
AGC
The IC is equipped with an AGC functionality to prevent overdriving the amplifier in case the
amplifier is operated at strong antenna signals, e.g., near transmitters. It is possible to realize
an additional antenna amplifier path with integrated AGC and external RF transistor. The
bandwidth of the integrated AGC circuit is 900MHz.
The amplifier output (RFC) is connected to a capacitive voltage divider and the divided signal
is applied to the AGC level detector at pin DET. This level detector input is optimized for low
distortion. The rectified signal is compared against an internal reference. The divider ratio of
the external voltage divider defines the AGC’s threshold. If the threshold is reached, pin PD1
drives a positive current through one or two external pin diodes in shunt configuration. In case
the limiting range of the shunt configuration is not sufficient, an additional pin diode in serial
configuration can be added and controlled via pin PD2. The current from PD2 through the
serial pin diode is opposite to the current of PD1. This helps to limit the amplifier input signal
and thus to prevent the FM amplifier from signal overdrive.
The drivers required for the external pin diode(s) are built-in into the ATR4253 IC, which
reduces the BOM cost and the application size.
3
9194CS–AUDR–10/10
3.3
Supply Voltage Regulator
The driving voltage for an external power transistor is provided by an integrated regulator
circuit.
An overvoltage protection circuit detects overvoltage condition and switches off the amplifier
and AGC circuit in order to reduce current consumption and avoid thermal overload.
3.4
Antenna Sensor
The Atmel® ATR4253 provides a built-in antenna sensor that detects if the antenna is properly
connected to the amplifier module. If no antenna is detected, the amplifier and AGC circuit are
switched off to signal this error via supply current reduction to the unit that provides and monitors the supply current for the antenna amplifier (e.g., the car radio).
4
Atmel ATR4253
9194CS–AUDR–10/10
Atmel ATR4253
4. Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Parameters
Pin
Symbol
Min.
Max.
Unit
Supply voltage
6
VS
–0.3
+12
V
Antenna sense current
1
ANT SENSE
–500
+500
µA
Comparator input current
2
VSTART
0
2
mA
Overvoltage detector
3
OVDET
–0.3
+3.3
V
Collector of FM amplifier
9
RFC
3
16
V
Ptot
700
mW
Junction temperature
Tj
150
°C
Ambient temperature
Tamb
–40
+115
°C
Tstg
–50
+150
°C
VHBM
–2
+2
kV
Power dissipation
Storage temperature
ESD HBM
All
5. Thermal Resistance
Parameters
Junction ambient, soldered on PCB, dependent on PCB layout
Symbol
Value
Unit
RthJA
40
K/W
6. Operating Range
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Supply voltage
Normal operation
6
VS
7.5
10
11
V
Supply voltage
Performance may be reduced, no
malfunction
6
VS
7
11
V
FM emitter current
Thermal condition
11
IRFE
35
mA
5
9194CS–AUDR–10/10
7. Electrical Characteristics
VS = 10 V, Tamb = 25°C, unless otherwise specified.
No.
1.1
2
Parameters
Supply current
Test Conditions
Pin
Symbol
AGC OFF
VS
Is
AGC ON ; includes 7 mA
pin diode current
VS
Tamb = –40 to +115°C;
AGC ON; includes 7mA
pin diode current and
31mA RF current
Min.
Typ.
Max.
Unit
Type*
12
mA
B
Is
19
mA
B
VS, RFC
Is, IRFC
50
mA
C
Common base
RFC
IRFC
31
mA
B
Common emitter
RFC
IRFC
35
mA
A
f = 100MHz
RF IN
RFMIN
50
Ω
C
Ω
C
70
RF Amplifier
2.3
Supply current(1)
2.4
Supply current
(2)
2.6
Input resistance
2.7
Output resistance
f = 100MHz
RF OUT
RFMOUT
50
2.8
Power gain
f = 100MHz
RF IN, RF OUT
G
5.2
dB
C
2.9
OIP3 at FMOUT
Common base
RF OUT
146
dBµV
C
2.10 NF
Common base
RF OUT
1.6
dB
C
2.11 Power gain
f = 100MHz, common
emitter
RF OUT
13.5
dB
B
2.12 OIP3 at FMOUT
Common emitter
RF OUT
140
dBµV
B
2.13 NF
Common emitter
RF OUT
3.5
dB
C
Maximum operating
2.14
frequency
3dB corner, common
emitter
RF OUT
450
MHz
C
mA
D
mA
A
3
G
AGC
3.4
Maximum pin diode
current
AGC active, 115°C
PD1
12
3.5
Maximum pin diode
current
AGC not active
PD2
12
3.6
Input resistance
3.7
Input capacitance
4
f = 100MHz
19
DET
RDET
17
25
kΩ
C
DET
CDET
1.5
2.0
pF
C
10.5
V
A
dB
C
Voltage Regulator / Monitor
4.1
Output voltage of
regulator
Battery voltage
VB = 14V
4.2
Ripple rejection of
regulator
100Hz, VB > VS + 1V
VS
9.5
10
VB, RF OUT
40
50
*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
Notes:
1. Current defined by R11= 68Ω
2. Current defined by R11= 56Ω
6
Atmel ATR4253
9194CS–AUDR–10/10
Atmel ATR4253
8. Ordering Information
Extended Type Number
Package
Remarks
ATR4253-PVPW
VQFN 3x3 / 16L
Taped on reel, 2k volume
ATR4253-PVQW
VQFN 3x3 / 16L
Taped on reel, 8k volume
9. Package Information
Top View
D
16
1
E
technical drawings
according to DIN
specifications
A
A3
Side View
A1
PIN 1 ID
Bottom View
COMMON DIMENSIONS
D2
(Unit of Measure = mm)
4
3
9
10
11
12
e
2
E2
5 6 7 8
MIN
NOM
MAX
A
0.8
0.9
1
A1
0.0
0.02
0.05
A3
0.15
0.2
0.25
D
2.9
3
3.1
D2
1.7
1.75
1.8
E
2.9
3
3.1
E2
1.7
1.75
1.8
L
0.3
0.4
0.5
b
e
0.18
0.25
0.5 BSC
0.32
NOTE
b
1
Symbol
L
16 15 14 13
Package Drawing Contact:
packagedrawings@atmel.com
TITLE
Package: VQFN_3x3_16L
Exposed pad 1.75 x 1.75
11/11/09
DRAWING NO. REV.
6.543-5164.01-4
1
7
9194CS–AUDR–10/10
10. Revision History
Please note that the following page numbers referred to in this section refer to the specific revision
mentioned, not to this document.
8
Revision No.
History
9194CS-AUDR-10/10
• Ordering Information table changed
9194BS-AUDR-09/10
• Section 6 “Operating Range” on page 5 changed
Atmel ATR4253
9194CS–AUDR–10/10
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