ATMEL ATR4252-RAQW

Features
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Highly Integrated - All-in-one Active Antenna IC
Integrated AGC for AM and FM
Integrated Driver for AM and FM PIN Diodes
Integrated Power Supply Regulator
Integrated Antenna Sensor
Separated AM LNA, AM Buffer and FM Amplifier
High Dynamic Range for AM and FM
Excellent Noise Performance
High Intercept Point 3rd Order for FM
FM Amplifier Adjustable to Various Cable Impedances
High Intercept Point 2nd and 3rd Order for AM
Low Noise Output Voltage
Low Power Consumption
Low Output Impedance AM
Only Small Capacitor Values Necessary at AM AGC
Large AM Frequency Range to Cover DRM Broadcast Signals
All-in-One IC
Solution for
Active
Antennas
ATR4252
1. Description
The ATR4252 is a highly integrated high performance AM/FM antenna amplification
IC with several features. The device has built-in AGC's for both AM and FM, antenna
detection, a power supply regulator as well as additional pre-integrated peripherals.
Summary
The ATR4252 is based on BICMOS technology. The device is designed in particular
for car application and is suitable for active antennas located in several positions on
the car such as bumpers, windscreen, mirrors or windows.
Preliminary
Figure 1-1.
Block Diagram
AM LNA IN
23
AM LNA
SOURCE
24
AM LNA
BIAS
REF
AMPD
GND2
FM
BIAS
FMB
FME
FMPD
22
21
20
19
18
17
16
15
FM
Amplifier
AM
LNA
14
FMC
13
FMDET
CASCODE
25
FILTER
12
FMTC
AM LNA OUT
26
11
VS
AMBIAS
27
10
AMOUT
AMBUF IN
28
9
GND1
AGC
(FM)
Voltage
Supply
Antenna
Detect
Over
Voltage
AGC
(AM)
AM
Buffer
1
2
3
4
5
6
7
8
NOTE: This is a summary document.
The complete document is available
under NDA. For more information,
please contact your local Atmel sales
office.
ANTENNA
VS VSTART OVDET VREGO AMTC1 AMTC2 AMDET
SENSE FILTER
9154AS–AUDR–09/09
2. Pin Configuration
Table 2-1.
2
AM LNABIAS
REF
AMPD
GND2
FMBIAS
FMB
FME
FMPD
Pinning VQFN 4x5 / 28L
22
21
20
19
18
17
16
15
AM LNA IN
23
14
FMC
AM LNA SOURCE
24
13
FMDET
CASCODE FILTER
25
12
FMTC
11
VS
10
AMOUT
2
3
4
5
6
7
8
AMDET
9
1
AMTC2
28
AMTC1
AMBUF IN
VREGO
27
OVDET
AMBIAS
VSTART
26
VS FILTER
AM LNA OUT
ATR4252
ANTENNA SENSE
Figure 2-1.
GND1
Pin Description
Pin
Symbol
Function
1
ANTENNA SENSE
2
VS FILTER
3
VSTART
Comparator input of voltage detector
4
OVDET
Overvoltage detection input
5
VREGO
Output of voltage regulator
6
AMTC1
AM AGC time-constant capacitance 1
7
AMTC2
AM AGC time-constant capacitance 2
8
AMDET
Level detector input of AM-AGC
Antenna sense input
Supply voltage filter input
9
GND1
10
AMOUT
11
VS
12
FMTC
13
FMDET
Level detector input of FM-AGC
14
FMC
Collector of FM amplifier (NPN)
15
FMPD
16
FME
17
FMB
18
FMBIAS
19
GND2
Ground AM
AM output, impedance matching
Supply voltage
FM AGC time constant
FM AGC output for pin diode
FM amplifier emitter(NPN)
FM amplifier base (NPN)
Reference voltage 2.7V FM
Ground FM
ATR4252 [Preliminary]
9154AS–AUDR–09/09
ATR4252 [Preliminary]
Table 2-1.
Pin Description (Continued)
Pin
Symbol
20
AMPD
Function
AM AGC output for pin diode
21
REF
22
AM LNA BIAS
Reference voltage 6V
23
AM LNA IN
24
AM LNA SOURCE
AM LNA source terminal
25
CASCODE FILTER
AM Cascode filter terminal
26
AM LNA OUT
27
AMBIAS
28
AMBUF IN
Paddle
GND
Reference voltage for AM LNA IN
AM LNA input terminal
AM LNA output terminal
Reference voltage for AMBUF IN
AM Buffer amplifier input, impedance matching
Ground paddle
3
9154AS–AUDR–09/09
3. Functional Description
The ATR4252 is a highly integrated AM/FM antenna IC with lots of features and functions. In fact
the most important feature is the impedance matching on both the antenna input and the cable.
The ATR4252 compensates cable losses between the antenna (for example, windscreen, roof
or bumper antennas) and the car radio, which is usually placed far away from the antenna.
AM means long wave (LW), medium wave (MW) and short wave (SW) frequency bands
(150 kHz to 30 MHz) that are usually used for AM as well as for DRM transmissions, and FM
means any of the world wide used frequency bands for FM radio broadcast (70 MHz to
110 MHz).
Two separate amplifier chains are used for AM and FM due to the different operation frequencies and requirements in the AM and FM band. This allows the use of separate antennas (e.g.,
windscreen antennas) for AM and FM. Of course, both amplifier chain inputs can also be connected to one antenna (e.g., roof antenna).
The AM amplifier chain is separated into two amplifiers. The first one is an LNA that is optimized
for low noise figure and low input capacitance. The second amplifier (AM buffer) is optimized to
drive a possibly long antenna cable with high parasitic capacitance. Both amplifiers have outstanding large signal performance. All input and output terminals of these two amplifiers are
accessible from outside so they can be connected together according to the application needs.
Additionally, a filter can be inserted between LNA output and buffer amplifier input.
For AM and FM amplifier chain, two separate automatic gain control (AGC) circuits have been
integrated in order to avoid overdriving the amplifiers in large signal conditions. The two separate AGC loops prevent strong AM signals from blocking FM stations and vice versa.
The integrated PIN diode drivers reduce the external component cost and board space.
A voltage regulation stage is integrated in order to further reduce the external component costs.
This stage provides overvoltage protection and current limitation. An external transistor is used
as power driver for this stage.
3.1
AM Amplifier
Due to the long wavelength in AM bands, the antennas used for AM reception in automotive
applications are short compared to the wavelength. Therefore, these antennas do not provide
50Ω output impedance, but have an output impedance of some pF. If these (passive) antennas
are connected to the car radio by a long cable, the capacitive load of this cable (some 100 pF)
dramatically reduces the signal level at the tuner input.
In order to overcome this problem, ATR4252 provides two AM amplifiers, one LNA and one AM
buffer amplifier. These two amplifiers can be used independently because all input/output terminals and bias inputs are externally accessible for the application.
The AM LNA has low input capacitance (12 pF typically) to reduce the capacitive load at the
antenna and provides a voltage gain of typically 9 dB that can be varied from 0 to 15 dB depending on external application.
4
ATR4252 [Preliminary]
9154AS–AUDR–09/09
ATR4252 [Preliminary]
The AM buffer amplifier has a very low input capacitance of typically 2.45 pF and can also be
connected directly to the car antenna if no additional gain is required. Due to the low output
impedance of 8Ω, the buffer amplifier is perfectly suited to drive the capacitive load of long
antenna cables. The voltage gain of this amplifier is close to 1 (0 dB), but the insertion gain that
is achieved when the buffer amplifier is inserted between antenna output and antenna cable
may be much higher (up to 35 dB). The actual value, of course, depends on antenna and cable
capacitances.
The input of the buffer amplifier is connected by an external 4.7 MΩ resistor to the bias voltage in
order to maintain high input impedance and low noise voltage.
AM tuners in car radios usually use PIN diode attenuators at their input. These PIN diode attenuators attenuate the signal by reducing the input impedance of the tuner. Therefore, a series
resistor is used at the AM amplifier output in the standard application. This series resistor guarantees well-defined source impedance for the radio tuner and protects the output of the AM
amplifier from short circuit by the PIN diode attenuator in the car radio.
3.2
AM AGC
The IC is equipped with an AM AGC capability to prevent overdriving of the amplifier in case the
amplifier operates near strong signal sources, e.g., transmitters.
The AM amplifier output AMOUT is applied to a resistive voltage divider. This divided signal
feeds the AGC level detector input pin AMDET. The rectified signal is compared against an internal reference. The threshold of the AGC can be adjusted by modification of the divider ratio of
the external voltage divider. If the threshold is reached ,the pin AMPD opens an internal transistor, which controls the pin diode current and limits the antenna signal to prevent an overdriving
of the AM amplifier.
As the AM AGC has to react very slowly, large capacitors are usually needed for this time delay.
To reduce the cost of the external components, a current control for the time delay is integrated,
so that only small external capacitor values are needed.
The necessary driver for the external pin diode is already incorporated in the ATR4252 IC, which
reduces the BOM cost and the application size.
3.3
FM Amplifier
The FM amplifier is realized with a high performance single NPN transistor. This allows the use
of an amplifier configuration, which is optimized for the desired requirements. For low cost application, the common emitter configuration provides good performance at reasonable BOM cost.
For high end application, common base configuration with lossless transformer feedback provides high IP3 and low noise figure at reasonable current consumption. In both configurations,
gain, input and output impedance can be adjusted by modification of external components.
The temperature compensated bias voltage (FMBIAS) for the base of the NPN transistor is
derived from an integrated voltage reference. The bias current of the FM amplifier is defined by
an external resistor.
5
9154AS–AUDR–09/09
3.4
FM AGC
The IC is equipped with an AGC capability to prevent overdriving of 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 900 MHz.
FM amplifier output FMC is connected to a capacitive voltage divider and the divided signal is
applied to the AGC level detector at pin FMDET. This level detector input is optimized for low
distortion. The rectified signal is compared against an internal reference. The threshold of the
AGC can be adjusted by tuning the divider ratio of the external voltage divider. If the threshold is
reached, pin FMPD opens an internal transistor, which controls the pin-diode current. By these
means, the amplifier input signal is limited and therefore the FM amplifier is prevented from signal overdrive.
The necessary driver for the external pin diode is already incorporated in the ATR4252 IC, which
reduces the BOM cost and the application size.
3.5
Supply Voltage Regulator
The driving voltage for an external power transistor is provided by an integrated regulator circuit.
An overvoltage protection circuit recognizes overvoltage condition and switches off the amplifier
and AGC circuits in order to reduce current consumption and avoid thermal overload.
3.6
Antenna Sensor
In addition, an antenna sensor has been integrated in order to recognize if the antenna is properly connected to the amplifier module. If no antenna is detected, the amplifier and AGC circuits
are switched off in order to signal this error via reduction of supply current consumption to the
unit that provides and monitors the supply current for the antenna amplifier (e.g., the car radio).
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.
Reference point is ground.
Parameters
Pin
Symbol
Min.
Max.
Unit
Supply voltage
11
VS
–0.3
+12
V
Collector of FM amplifier
14
FMC
3
16
V
AM LNA input terminal
23
AM LNA IN
0
2
V
AM LNA output terminal
26
AM LNA OUT
7
12
V
Ptot
1200
mW
Junction temperature
Tj
150
°C
Ambient temperature
Tamb
–40
+105
°C
Tstg
–50
+150
°C
VHBM
–2
+2
kV
Power dissipation
Storage temperature
ESD HBM
6
all
ATR4252 [Preliminary]
9154AS–AUDR–09/09
ATR4252 [Preliminary]
5. Electrical Characteristics
Verified on test circuits (demo design made by Atmel), VS = 10 V, Tamb = 25°C, unless otherwise specified
No.
1.1
2
Parameters
Test Conditions
Supply current
Pin
Symbol
AGC OFF
VS, FMC,
AM LNA OUT
Min.
Typ.
Is
77
FMAGC ON
VS, FMC,
AM LNA OUT
Is
85
Tamb = –40 to +105°C;
FMAGC ON
VS, FMC,
AM LNA OUT
Is
CAMLNAIN
Max.
Unit
mA
95
mA
99
mA
AM LNA+ Buffer(2)
2.1
Input capacitance
f = 1 MHz
AM LNA IN
2.4
Voltage gain
f = 1 MHz
AM/FM-OUT
2.5
Input noise voltage
Buffer OUT,
RBIAS = 4.7 MΩ, B = 9 kHz
f = 1 MHz
Antenna
Dummy Input
2.7
Maximum operating
frequency
3 dB corner
AM/FM-OUT
OIP3(1)
AM/FM Out;
finp = 1 MHz + 1.1 MHz,
Vout = 110 dBµV,
1K II 500 pF load,
Vs = 10V
144
dBµV
OIP2(1)
AM/FM Out;
finp = 1 MHz + 1.1 MHz,
Vout = 110 dBµV,
1K II 500 pF load,
Vs = 10V
170
dBµV
kΩ
2.8
2.9
4
pF
9
dB
–12
dBµV
30
MHz
AM AGC
4.1
Input resistance
4.2
Input capacitance
f = 1 MHz
4.4
3 dB corner frequency
AGC threshold increased by
3 dB
AM PD
4.5
Saturation voltage
10 mA
AM PD
4.6
Leakage current
4.7
Maximum PIN Diode
current
5
FM Amplifier
5.3
Supply current
(3)
AM DET
RAMDET
40
50
AM DET
CAMDET
2.6
3.2
AGC active
3.8
30
VS – 1.9
V
4
AM PD
22
pF
MHz
AM PD
µA
35
mA
Common base
FMC
IFMC
29
mA
Common emitter
FMC
IFMC
35
mA
5.4
Supply current
5.5
Maximum output
voltage
Vs = 10V
FMC
5.6
Input resistance
f = 100 MHz
FM IN
5.7
Maximum operating
frequency
3 dB corner,
common emitter
FM OUT
5.8
Output resistance
f = 100 MHz
FM OUT
Notes:
VN
12
12
RFMIN
Vpp
50
450
RFMOUT
Ω
MHz
50
Ω
1. AGC Loop deactivated
2. Measured with antenna dummy.
7
9154AS–AUDR–09/09
5. Electrical Characteristics (Continued)
Verified on test circuits (demo design made by Atmel), VS = 10 V, Tamb = 25°C, unless otherwise specified
No.
Parameters
Test Conditions
5.9
Power gain
f = 100 MHz,
common base circuit
5.10
OIP3 at FMOUT
Common base circuit
5.11
NF
Common base circuit
5.12
Power gain
f = 100 MHz,
common emitter circuit
5.13
OIP3 at FMOUT
Common emitter circuit
5.14
NF
Common emitter circuit
6
Maximum PIN Diode
current
6.5
Input resistance
6.6
Input capacitance
Min.
G
5
FM OUT
Typ.
Max.
Unit
8
dB
145
dBµV
1.9
dB
13.5
dB
FM OUT
140
dBµV
FM OUT
3.5
dB
12
14
mA
G
AGC active
FMPD
FM DET
RFMDET
17
21
25
kΩ
FM DET
CFMDET
1.5
1.75
2.0
pF
VS
9.5
10
10.5
V
VB, AM/FM-Out
40
50
f = 100 MHz
Voltage Regulator / Monitor
7.1
Output voltage of
regulator
Battery voltage
VB = 14V
7.2
Ripple rejection of
regulator
100 Hz, VB > VS + 1V
Notes:
Symbol
FM AGC
6.4
7
Pin
dB
1. AGC Loop deactivated
2. Measured with antenna dummy.
6. Ordering Information
Extended Type Number
Package
Remarks
ATR4252-RAPW
VQFN 4x5 / 28L
Taped on reel, 1.5k volume
ATR4252-RAQW
VQFN 4x5 / 28L
Taped on reel, 6k volume
8
ATR4252 [Preliminary]
9154AS–AUDR–09/09
ATR4252 [Preliminary]
7. Package Information
Top View
D
28
1
PIN 1 ID
E
technical drawings
according to DIN
specifications
8
A
Side View
A3
A1
Dimensions in mm
Bottom View
D2
9
14
15
8
COMMON DIMENSIONS
E2
(Unit of Measure = mm)
1
28
23
e
Z 10:1
L
Z
22
Symbol
MIN
NOM
MAX
A
0.8
0.9
1
A1
A3
0.0
0.15
0.02
0.2
0.05
0.25
D
3.9
4
4.1
D2
2.45
2.6
2.75
E
4.9
5
5.1
E2
3.45
3.6
3.75
L
0.3
0.4
0.5
b
e
0.16
0.23
0.5 BSC
0.3
NOTE
b
Package Drawing Contact:
packagedrawings@atmel.com
TITLE
Package: VQFN_4x5_28L
Exposed pad 2.6x3.6
06/18/08
DRAWING NO. REV.
6.543-5143.01-4
2
9
9154AS–AUDR–09/09
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9154AS–AUDR–09/09