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Features
* * * * * * * * * * * * * * * *
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 Summary Preliminary
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. 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. Figure 1-1. Block Diagram
AM LNA BIAS 22 REF 21 AMPD 20 GND2 19 FM BIAS 18 FMB 17 FME 16 FMPD 15
AM LNA IN AM LNA SOURCE
23
AM LNA
FM Amplifier 14 FMC
24
Voltage Supply
AGC (FM)
13
FMDET
CASCODE 25 FILTER 26
12
FMTC
AM LNA OUT
11
VS
AMBIAS
27
Antenna Detect
AM Buffer
Over Voltage
AGC (AM)
10
AMOUT
AMBUF IN
28
9
GND1
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
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2. Pin Configuration
Figure 2-1. Pinning VQFN 4x5 / 28L
AM LNABIAS FMBIAS
AMPD
22 AM LNA IN AM LNA SOURCE CASCODE FILTER AM LNA OUT AMBIAS AMBUF IN 23 24 25 26 27 28 1 ANTENNA SENSE
21
20
19
18
17
16
15 14 13 12 FMC FMDET FMTC VS AMOUT GND1
ATR4252
FMPD 11 10 9 8 AMDET
GND2
FMB 6 AMTC1
2 VS FILTER
3 VSTART
4 OVDET
5 VREGO
Table 2-1.
Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Pin Description
Symbol ANTENNA SENSE VS FILTER VSTART OVDET VREGO AMTC1 AMTC2 AMDET GND1 AMOUT VS FMTC FMDET FMC FMPD FME FMB FMBIAS GND2 Function Antenna sense input Supply voltage filter input Comparator input of voltage detector Overvoltage detection input Output of voltage regulator AM AGC time-constant capacitance 1 AM AGC time-constant capacitance 2 Level detector input of AM-AGC Ground AM AM output, impedance matching Supply voltage FM AGC time constant Level detector input of FM-AGC Collector of FM amplifier (NPN) FM AGC output for pin diode FM amplifier emitter(NPN) FM amplifier base (NPN) Reference voltage 2.7V FM Ground FM
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ATR4252 [Preliminary]
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AMTC2
FME 7
REF
ATR4252 [Preliminary]
Table 2-1.
Pin 20 21 22 23 24 25 26 27 28 Paddle
Pin Description (Continued)
Symbol AMPD REF AM LNA BIAS AM LNA IN AM LNA SOURCE CASCODE FILTER AM LNA OUT AMBIAS AMBUF IN GND Function AM AGC output for pin diode Reference voltage 6V Reference voltage for AM LNA IN AM LNA input terminal AM LNA source terminal AM Cascode filter terminal AM LNA output terminal Reference voltage for AMBUF IN AM Buffer amplifier input, impedance matching Ground paddle
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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 50 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.
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ATR4252 [Preliminary]
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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 8, 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 M 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.
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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 Supply voltage Collector of FM amplifier AM LNA input terminal AM LNA output terminal Power dissipation Junction temperature Ambient temperature Storage temperature ESD HBM all Pin 11 14 23 26 Symbol VS FMC AM LNA IN AM LNA OUT Ptot Tj Tamb Tstg VHBM -40 -50 -2 Min. -0.3 3 0 7 Max. +12 16 2 12 1200 150 +105 +150 +2 Unit V V V V mW C C C kV
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ATR4252 [Preliminary]
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ATR4252 [Preliminary]
5. Electrical Characteristics
Verified on test circuits (demo design made by Atmel), VS = 10 V, Tamb = 25C, unless otherwise specified No. Parameters Test Conditions AGC OFF 1.1 Supply current FMAGC ON Tamb = -40 to +105C; FMAGC ON 2 2.1 2.4 2.5 AM LNA+ Buffer(2) Input capacitance Voltage gain Input noise voltage Maximum operating frequency f = 1 MHz f = 1 MHz Buffer OUT, RBIAS = 4.7 M, B = 9 kHz f = 1 MHz 3 dB corner AM/FM Out; finp = 1 MHz + 1.1 MHz, Vout = 110 dBV, 1K II 500 pF load, Vs = 10V AM/FM Out; finp = 1 MHz + 1.1 MHz, Vout = 110 dBV, 1K II 500 pF load, Vs = 10V AM DET f = 1 MHz AGC threshold increased by 3 dB 10 mA AM DET AM PD AM PD AM PD AGC active AM PD 22 35 RAMDET CAMDET 40 2.6 30 VS - 1.9 4 AM LNA IN AM/FM-OUT Antenna Dummy Input AM/FM-OUT VN 30 CAMLNAIN 12 9 -12 pF dB dBV Pin VS, FMC, AM LNA OUT VS, FMC, AM LNA OUT VS, FMC, AM LNA OUT Symbol Is Is Is Min. Typ. 77 85 95 99 Max. Unit mA mA mA
2.7
MHz
2.8
OIP3(1)
144
dBV
2.9
OIP2(1)
170 50 3.2 3.8
dBV k pF MHz V A mA
4 4.1 4.2 4.4 4.5 4.6 4.7 5 5.3 5.4 5.5 5.6 5.7 5.8 Notes:
AM AGC Input resistance Input capacitance 3 dB corner frequency Saturation voltage Leakage current Maximum PIN Diode current FM Amplifier Supply current Supply current
(3)
Common base Common emitter Vs = 10V f = 100 MHz 3 dB corner, common emitter f = 100 MHz
FMC FMC FMC FM IN FM OUT FM OUT
IFMC IFMC 12 RFMIN 450 RFMOUT
29 35
mA mA Vpp
Maximum output voltage Input resistance Maximum operating frequency Output resistance
50
MHz
50
1. AGC Loop deactivated 2. Measured with antenna dummy.
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5. Electrical Characteristics (Continued)
Verified on test circuits (demo design made by Atmel), VS = 10 V, Tamb = 25C, unless otherwise specified No. 5.9 5.10 5.11 5.12 5.13 5.14 6 6.4 6.5 6.6 7 7.1 7.2 Notes: Parameters Power gain OIP3 at FMOUT NF Power gain OIP3 at FMOUT NF FM AGC Maximum PIN Diode current Input resistance Input capacitance Output voltage of regulator Ripple rejection of regulator f = 100 MHz Battery voltage VB = 14V 100 Hz, VB > VS + 1V Voltage Regulator / Monitor VS VB, AM/FM-Out 9.5 40 10 50 10.5 V dB AGC active FMPD FM DET FM DET RFMDET CFMDET 12 17 1.5 14 21 1.75 25 2.0 mA k pF Test Conditions f = 100 MHz, common base circuit Common base circuit Common base circuit f = 100 MHz, common emitter circuit Common emitter circuit Common emitter circuit FM OUT FM OUT G FM OUT Pin Symbol G Min. 5 145 1.9 13.5 140 3.5 Typ. Max. 8 Unit dB dBV dB dB dBV dB
1. AGC Loop deactivated 2. Measured with antenna dummy.
6. Ordering Information
Extended Type Number ATR4252-RAPW ATR4252-RAQW Package VQFN 4x5 / 28L VQFN 4x5 / 28L Remarks Taped on reel, 1.5k volume Taped on reel, 6k volume
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ATR4252 [Preliminary]
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ATR4252 [Preliminary]
7. Package Information
Top View D 28 1 PIN 1 ID
technical drawings according to DIN specifications
8
E
Dimensions in mm A1 A3 A Bottom View D2 9 14 15 COMMON DIMENSIONS
(Unit of Measure = mm)
Side View
8
E2
Symbol
A A1 A3 D D2 E E2 L b e
MIN
0.8 0.0 0.15 3.9 2.45 4.9 3.45 0.3 0.16
NOM
0.9 0.02 0.2 4 2.6 5 3.6 0.4 0.23 0.5 BSC
MAX
1 0.05 0.25 4.1 2.75 5.1 3.75 0.5 0.3
NOTE
1
22 28 e 23
Z
Z 10:1
b
L
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
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