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AD8315 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer AD8315
Beschreibung 50 dB GSM PA Controller
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 23 Seiten
AD8315 Datasheet, Funktion
Data Sheet
50 dB GSM PA Controller
AD8315
FEATURES
Complete RF detector/controller function
>50 dB range at 0.9 GHz (−49 dBm to +2 dBm, re 50 Ω)
Accurate scaling from 0.1 GHz to 2.5 GHz
Temperature-stable linear-in-dB response
Log slope of 23 mV/dB, intercept at −60 dBm at 0.9 GHz
True integration function in control loop
Low power: 20 mW at 2.7 V, 38 mW at 5 V
Power-down to 10.8 μW
APPLICATIONS
Single, dual, and triple band mobile handset (GSM, DCS, EDGE)
Transmitter power control
GENERAL DESCRIPTION
The AD8315 is a complete low cost subsystem for the precise
control of RF power amplifiers operating in the frequency range
0.1 GHz to 2.5 GHz and over a typical dynamic range of 50 dB.
It is intended for use in cellular handsets and other battery-
operated wireless devices. The log amp technique provides a much
wider measurement range and better accuracy than controllers
using diode detectors. In particular, the temperature stability is
excellent over a specified range of −30°C to +85°C.
Its high sensitivity allows control at low signal levels, thus
reducing the amount of power that must be coupled to
the detector.
For convenience, the signal is internally ac-coupled. This
high-pass coupling, with a corner at approximately 0.016 GHz,
determines the lowest operating frequency. Therefore, the
source can be dc grounded.
The AD8315 provides a voltage output, VAPC, that has the
voltage range and current drive to directly connect to most
handset power amplifiers’ gain control pin. VAPC can swing
from 250 mV above ground to within 200 mV below the supply
voltage. Load currents of up to 6 mA can be supported.
The setpoint control input is applied to the VSET pin and has
an operating range of 0.25 V to 1.4 V. The associated circuit
determines the slope and intercept of the linear-in-dB
measurement system; these are nominally 23 mV/dB and
−60 dBm for a 50 Ω termination (−73 dBV) at 0.9 GHz.
Further simplifying the application of the AD8315, the input
resistance of the setpoint interface is over 100 MΩ, and the bias
current is typically 0.5 μA.
The AD8315 is available in MSOP and LFCSP packages and
consumes 8.5 mA from a 2.7 V to 5.5 V supply. When powered
down, the sleep current is 4 μA.
FUNCTIONAL BLOCK DIAGRAM
VPOS
ENBL
LOW NOISE
GAIN BIAS
LOW NOISE
BAND GAP
REFERENCE
OUTPUT
ENABLE
DELAY
RFIN
DET
DET
DET
DET
DET
10dB
10dB
10dB
10dB
×1.35
HI-Z
VAPC
LOW NOISE (25nV/Hz)
RAIL-TO-RAIL BUFFER
FLTR
COMM
OFFSET
COMP’N
INTERCEPT
POSITIONING
VSET
V-I
23mV/dB
250mV TO
1.4V = 50dB
Figure 1.
Rev. D
Document Feedback
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responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
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Tel: 781.329.4700 ©1999–2016 Analog Devices, Inc. All rights reserved.
Technical Support
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AD8315 Datasheet, Funktion
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter
Supply Voltage VPOS
Temporary Overvoltage VPOS
(100 cycles, 2 sec duration, ENBL Low)
VAPC, VSET, ENBL
RFIN
Equivalent Voltage
Internal Power Dissipation
θJA (MSOP)
θJA (LFCSP, Paddle Soldered)
θJA (LFCSP, Paddle Not Soldered)
Maximum Junction Temperature
Operating Temperature Range
Storage Temperature Range
Lead Temperature (Soldering 60 sec)
MSOP
LFCSP
Rating
5.5 V
6.3 V
0 V, VPOS
17 dBm
1.6 V rms
60 mW
200°C/W
80°C/W
200°C/W
125°C
−40°C to +85°C
−65°C to +150°C
300°C
240°C
AD8315
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
ESD CAUTION
Rev. D | Page 5 of 22

6 Page









AD8315 pdf, datenblatt
Data Sheet
GND
VAPC
AVERAGE = 16 SAMPLES
200mV PER
VERTICAL
DIVISION
GND
VS
AND
VENBL
1V PER
VERTICAL
DIVISION
2µs PER
HORIZONTAL
DIVISION
Figure 28. Power-On and Power-Off Response with VSET Grounded
R AND S
SMT03
SIGNAL
GENERATOR
10MHz REF
OUTPUT
RF OUT
EXT TRIG
STANFORD DS345
PULSE
GENERATOR
TRIG
OUT
PULSE OUT
AD811
49.9
52.3
AD8315
1 RFIN
VPOS 8
2 ENBL VAPC 7
3 VSET
NC 6
732
TEK P6205
FET PROBE
TEK P6205
FET PROBE
TRIG
TEK TDS694C
SCOPE
220pF
4 FLTR COMM 5
NC = NO CONNECT
Figure 29. Test Setup for Power-On and Power-Off Response with VSET Grounded
GND
VAPC
500mV PER
VERTICAL
DIVISION
AD8315
GND
VS
1V PER
VERTICAL
DIVISION
2µs PER
HORIZONTAL
DIVISION
AVERAGE = 16 SAMPLES
Figure 30. Power-On and Power-Off Response with VSET and ENBL Grounded
R AND S
SMT03
SIGNAL
GENERATOR
10MHz REF
OUTPUT
RF OUT
EXT TRIG STANFORD DS345
PULSE
GENERATOR
TRIG
OUT
PULSE OUT
AD811
49.9
52.3
AD8315
1 RFIN
VPOS 8
2 ENBL VAPC 7
3 VSET
NC 6
732
TEK P6205
FET PROBE
TEK P6205
FET PROBE
TRIG
TEK TDS694C
SCOPE
220pF
4 FLTR COMM 5
NC = NO CONNECT
Figure 31. Test Setup for Power-On and Power-Off Response with VSET
and ENBL Grounded
Rev. D | Page 11 of 22

12 Page





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