Analog Devices AD8318 Datasheet
1 MHz – 8 GHz, 60 dB
FEATURES
Wide bandwidth: 1 MHz to 8 GHz
High accuracy: ±1.0 dB over 55 dB range (f < 5.8 GHz)
Stability over temperature: ±0.5 dB
Low noise measurement/controller output VOUT
Pulse response time 10/12 ns (fall/rise)
Integrated temperature sensor
Small footprint CSP package
Power-down feature: <1.5 mW at 5 V
Single-supply operation: 5V @ 68 mA
Fabricated using high speed SiGe process
APPLICATIONS
RF transmitter PA setpoint control and level monitoring
RSSI measurement in base stations, WLAN, radar
GENERAL DESCRIPTION
The AD8318 is a demodulating logarithmic amplifier, capable of
accurately converting an RF input signal to a corresponding
decibel-scaled output voltage. It employs the progressive
compression technique over a cascaded amplifier chain, each
stage of which is equipped with a detector cell. The device can be
used in measurement or controller mode. The AD8318
maintains accurate log conformance for signals of 1 MHz to
6 GHz and provides useful operation to 8 GHz. The input range
is typically 60 dB (re: 50 Ω) with error less than ±1 dB. The
AD8318 has a 10 ns response time that enables RF burst
detection to beyond 60 MHz. The device provides
unprecedented logarithmic intercept stability versus ambient
temperature conditions. A 2 mV/K slope temperature sensor
output is also provided for additional system monitoring. A
single supply of +5 V is required. Current consumption is
typically 68 mA. Power consumption decreases to <1.5 mW
when the device is disabled.
The AD8318 can be configured to provide a control voltage to a
VGA, such as a power amplifier or a measurement output, from
pin VOUT. Since the output can be used for controller
Logarithmic Detector/Controller
AD8318
FUNCTIONAL BLOCK DIAGRAM
VPSI ENBL TADJ VPSO
TEMP
INHI
INLO
TEMP
SENSOR
DET DET DET DET
applications, special attention has been paid to minimize
wideband noise. In this mode, the setpoint control voltage is
applied to VSET. The feedback loop through an RF
amplifier is closed via VOUT; the output of which regulates
the amplifier’s output to a magnitude corresponding to V
The AD8318 provides 0 V to 4.9 V output capability at the
VOUT pin, suitable for controller applications. As a
measurement device, VOUT is externally connected to
VSET to produce an output voltage V
linear-in-dB function of the RF input signal amplitude.
The logarithmic slope is nominally −25 mV/dB, but can be
adjusted by scaling the feedback voltage from VOUT to the
VSET interface. The intercept is +20 dBm (re: 50 Ω, CW
input) using the INHI input. These parameters are very
stable against supply and temperature variations.
The AD8318 is fabricated on a SiGe bipolar IC process and
is available in a 4 mm × 4 mm, 16-pin LFCSP package, for
the operating temperature range of –40
GAIN
BIAS
SLOPE
Figure 1.
IV
IV
CMOPCMIP
that is a decreasing
OUT
o
C to +85oC.
VSET
VOUT
CLPF
04853-001
SET
.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no 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.
Trademarks and registered trademarks are the property of their respective
owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703 © 2003 Analog Devices, Inc. All rights reserved.
www.analog.com
AD8318
TABLE OF CONTENTS
Specifications...................................................................................3
Absolute Maximum Ratings ..........................................................6
ESD Caution................................................................................6
Pin Configuration and Functional Descriptions ........................7
Typical Performance Characteristics............................................8
General Description .................................................................... 11
Using the AD8318........................................................................ 12
Basic Connections ................................................................... 12
Enable........................................................................................ 12
Input Signal Coupling ............................................................. 12
Output Interface....................................................................... 13
Setpoint Interface..................................................................... 13
Temperature Compensation of Output Voltage .................. 13
Temperature Sensor................................................................. 14
Measurement Mode................................................................. 14
Device Calibration and Error Calculation............................ 15
Selecting Calibration Points to Improve Accuracy over a
Reduced Range
Variation in Temperature Drift from Device to Device ......17
Temperature Drift at Different Temperatures...................... 17
Setting the Output Slope in Measurement Mode ................ 17
Response Time Capability ......................................................18
Controller Mode....................................................................... 18
Characterization Setups and Methods.................................. 20
Evaluation Board ..........................................................................21
Outline Dimensions..................................................................... 23
Ordering Guide ........................................................................23
......................................................................... 16
REVISION HISTORY
7/04—Revision 0: Initial Version
Rev. 0 | Page 2 of 24
AD8318
SPECIFICATIONS
VP = 5 V, C
Table 1.
Parameter Conditions Min Typ Max Unit
SIGNAL INPUT INTERFACE INHI (Pin 14) and INLO (Pin 15)
Specified Frequency Range
DC Common-Mode Voltage VPOS – 1.8 V
MEASUREMENT MODE
f = 900 MHz 500 Ω at TADJ to GND
Input Impedance 957 || 0.71
±1 dB Dynamic Range TA = +25°C
Maximum Input Level
Minimum Input Level
Slope −26 –24.5 −23 mV/dB
Intercept 19.5 22 24 dBm
Output Voltage—High Power In PIN = –10 dBm 0.7 0.78 0.86 V
Output Voltage—Low Power In PIN = –40 dBm 1.42 1.52 1.62 V
Temperature Sensitivity PIN = –10 dBm
f = 1.9 GHz 500 Ω at TADJ to GND
Input Impedance 523 || 0.68
±1 dB Dynamic Range TA = +25°C
Maximum Input Level
Minimum Input Level
Slope −27 –24.4 −22 mV/dB
Intercept 17 20.4 24 dBm
Output Voltage—High Power In PIN = –10 dBm 0.63 0.73 0.83 V
Output Voltage—Low Power In PIN = –35 dBm 1.2 1.35 1.5 V
Temperature Sensitivity PIN = –10 dBm
f = 2.2 GHz 500 Ω at TADJ to GND
Input Impedance 391 || 0.66
±1 dB Dynamic Range TA = +25°C
Maximum Input Level
Minimum Input Level
Slope −28 –24.4 −21.5 mV/dB
Intercept 15 19.6 25 dBm
Output Voltage—High Power In PIN = –10 dBm 0.63 0.73 0.84 V
Output Voltage—Low Power In PIN = –35 dBm 1.2 1.34 1.5 V
Temperature Sensitivity PIN = –10 dBm
= 220 pF, TA = +25°C, 52.3 Ω termination resistor at INHI, unless otherwise noted.
LPF
0.001 8 GHz
VOUT (Pin 6) shorted to VSET (Pin 7), sinusoidal
input signal
57 dB
−40°C < T
±1 dB Error
±1 dB Error
25°C ≤ T
≤ +85°C
A
−40°C ≤ T
< +85°C
A
≤ +25°C
A
48 dB
–1 dBm
–58 dBm
+0.0011
+0.003
57 dB
−40°C < T
±1 dB Error
±1 dB Error
25°C ≤ T
≤ +85°C
A
–40°C ≤ T
< +85°C
A
≤ +25°C
A
50 dB
–2 dBm
–59 dBm
+0.0011
+0.0072
58 dB
−40°C < T
±1 dB Error
±1 dB Error
25°C ≤ T
≤ +85°C
A
–40°C ≤ T
< +85°C
A
≤ +25°C
A
50 dB
–2 dBm
–60 dBm
−0.0005
+0.0062
Ω || pF
dB/°C
dB/°C
Ω || pF
dB/°C
dB/°C
Ω || pF
dB/°C
dB/°C
Rev. 0 | Page 3 of 24
AD8318
Parameter Conditions Min Typ Max Unit
f = 3.6 GHz 51 Ω at TADJ to GND
Input Impedance 119 || 0.7
±1 dB Dynamic Range TA = +25°C
Maximum Input Level
Minimum Input Level
−40°C < T
±1 dB Error
±1 dB Error
< +85°C
A
58 dB
42 dB
–2 dBm
–60 dBm
Slope –24.3 mV/dB
Intercept 19.8 dBm
Output Voltage—High Power In PIN = –10 dBm 0.717 V
Output Voltage—Low Power In PIN = –40 dBm 1.46 V
Temperature Sensitivity PIN = –10 dBm
25°C ≤ T
–40°C ≤ T
≤ +85°C
A
≤ +25°C
A
+0.0022
+0.004
f = 5.8 GHz 1000 Ω at TADJ to GND
Input Impedance
±1 dB Dynamic Range TA = +25°C
Maximum Input Level
Minimum Input Level
Slope
Intercept
−40°C < T
±1 dB Error
±1 dB Error
< +85°C
A
33 || 0.59
57 dB
48 dB
–1 dBm
–58 dBm
–24.3 mV/dB
25 dBm
Output Voltage—High Power In PIN = –10 dBm 0.86 V
Output Voltage—Low Power In PIN = –40 dBm 1.59 V
Temperature Sensitivity PIN = –10 dBm
25°C ≤ T
–40°C ≤ T
≤ +85°C
A
≤ +25°C
A
+0.0033
+0.0069
f = 8.0 GHz 500 Ω at TADJ to GND
±3 dB Dynamic Range TA = +25°C
Maximum Input Level
Minimum Input Level
Slope
Intercept
−40°C < T
±3 dB Error
±3 dB Error
< +85°C
A
60 dB
58 dB
3 dBm
–55 dBm
–23 mV/dB
37 dBm
Output Voltage—High Power In PIN = –10 dBm 1.06 V
Output Voltage—Low Power In PIN = –40 dBm 1.78 V
Temperature Sensitivity PIN = –10 dBm
25°C ≤ T
–40°C ≤ T
≤ +85°C
A
≤ +25°C
A
+0.028
−0.0085
OUTPUT INTERFACE VOUT (Pin 6)
Voltage Swing VSET = 0 V; RFIN = –10 dBm, no load
VSET = 2.1 V; RFIN = –10 dBm, no load
1
1
4.9 V
25 mV
Output Current Drive VSET = 1.5 V, RFIN = –50 dBm 60 mA
Small Signal Bandwidth RFIN = −10 dBm; From CLPF to VOUT 600 MHz
Output Noise
RF Input = 2.2 GHz, –10 dBm, f
= 100 kHz,
NOISE
90
CLPF = 220 pF
Ω || pF
dB/°C
dB/°C
Ω || pF
dB/°C
dB/°C
dB/°C
dB/°C
nV/√Hz
Rev. 0 | Page 4 of 24
AD8318
Parameter Conditions Min Typ Max Unit
Fall Time Input Level = off to –10 dBm, 90% to 10% 10 ns
Rise Time Input Level = –10 dBm to off, 10% to 90% 12 ns
VSET INTERFACE VSET (Pin 7)
Nominal Input Range RFIN = 0 dBm; measurement mode
RFIN = –65 dBm; measurement mode
Logarithmic Scale Factor –0.04 dB/mV
Bias Current Source RFIN = −10 dBm; VSET = 2.1 V 2.5
TEMPERATURE REFERENCE TEMP (Pin 13)
Output Voltage
Temperature Slope
Current Source/Sink
= 25°C, RL = 10 kΩ
T
A
–40°C ≤ T
= 25°C
T
A
≤ +85°C, RL = 10 kΩ
A
POWER-DOWN INTERFACE ENBL (Pin 16)
Logic Level to Enable Device 1.7 V
ENBL Current When Enabled ENBL = 5 V <1
ENBL Current When Disabled ENBL = 0 V; Sourcing 15
POWER INTERFACE VPSI (Pins 3, 4), VPSO (Pin 9)
Supply Voltage 4.5 5 5.5 V
Quiescent Current ENBL = 5 V 50 68 52 mA
vs. Temperature
–40°C ≤ T
≤ +85°C
A
Supply Current when Disabled ENBL = 0 V, Total Currents for VPSI and VPSO 260
vs. Temperature
1
Controller mode
2
(Gain = 1) For other gains, see Measurement Mode section of the data sheet.
–40°C ≤ T
≤ +85°C
A
2
2
0.5
2.1 V
µA
0.57 0.6 0.63 V
2
mV/°C
10/0.1 mA
µA
µA
68 mA
µA
350
µA
Rev. 0 | Page 5 of 24
AD8318
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Supply Voltage: VPSO, VPSI
ENBL, VSET Voltage
Input Power (Single-ended, re: 50 Ω)
Internal Power Dissipation
1
θ
JA
Maximum Junction Temperature
Operating Temperature Range
Storage Temperature Range
Lead Temperature Range
1
With package die paddle soldered to thermal pads with vias connecting to inner
and bottom layers
5.7 V
0 to VP
12 dBm
0.73 W
55°C/W
125°C
–40°C to +85°C
–65°C to +150°C
260°C
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Stresses above those listed under Absolute Maximum
Ratings may cause permanent damage to the device. This is
a stress rating only; functional operation of the device at
these or any other conditions above those indicated in the
operational section of this specification is not implied.
Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
Rev. 0 | Page 6 of 24
AD8318
PIN CONFIGURATION AND FUNCTIONAL DESCRIPTIONS
12
CMIP11CMIP10TADJ9VPSO
13
TEMP
14
INHI
15
16
Figure 2. 16-Lead Lead Frame Chip Scale Package (LFCSP)
AD8318
INLO
ENBL
CMIP2CMIP3VPSI4VPSI
1
Table 3. Pin Function Descriptions
Pin No. Mnemonic Function
1, 2, 11, 12 CMIP Device Common (Input System Ground).
3, 4, 9 VPSI, VPSO Positive Supply Voltage for the Device Input System: 4.5 V to 5.5 V (voltage on all pins should be equal).
5 CLPF Loop Filter Capacitor.
6 VOUT Measurement and Controller Output.
CMOP
VSET
VOUT
CLPF
8
7
6
5
04853-002
7 VSET Setpoint Input for Controller Mode, or Feedback Input for Measurement Mode.
8 CMOP Device Common (Output System Ground).
10 TADJ Temperature Compensation Adjustment.
13 TEMP Temperature Sensor Output.
14 INHI
RF Input. Nominal input range: −60 dBm to 0 dBm re: 50 Ω; ac-coupled RF input.
15 INLO RF Common for INHI; ac-coupled RF common.
16 ENBL Device Enable. Connect to VPSI for normal operation. Connect pin to ground for disable mode.
Paddle Internally Connected to CMIP, Solder to Ground.
Rev. 0 | Page 7 of 24
AD8318
TYPICAL PERFORMANCE CHARACTERISTICS
VP = 5 V, T = +25°C, –40°C, +85°C; C
2.2
2.0
1.8
1.6
1.4
(V)
1.2
OUT
V
1.0
0.8
0.6
0.4
0.2
–65 –55 –45 –35 –25 –15 –5 5 15
Figure 3. V
and Log Conformance vs. Input Amplitude at 900 MHz,
OUT
PIN (dBm)
= 220 pF; T
LPF
Typical Device
2.2
2.0
1.8
1.6
1.4
(V)
1.2
OUT
V
1.0
0.8
0.6
0.4
0.2
–65 –55 –45 –35 –25 –15 –5 5 15
Figure 4. V
and Log Conformance vs. Input Amplitude at 1.9 GHz,
OUT
PIN (dBm)
Typical Device
2.2
2.0
1.8
1.6
1.4
(V)
1.2
OUT
V
1.0
0.8
0.6
0.4
0.2
–65 –55 –45 –35 –25 –15 –5 5 15
Figure 5. V
and Log Conformance vs. Input Amplitude at 3.6 GHz,
OUT
PIN (dBm)
Typical D evice, T
= 51 Ω
ADJ
= 500 Ω; unless otherwise noted. Colors: +25°C Black; –40°C Blue; +85°C Red
ADJ
2.0
1.6
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
–2.0
2.0
1.6
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
–2.0
ERROR (dB)
04853-003
ERROR (dB)
04853-004
2.2
2.0
1.8
1.6
1.4
(V)
1.2
OUT
V
1.0
0.8
0.6
0.4
0.2
–65 –55 –45 –35 –25 –15 –5 5 15
Figure 6. V
and Log Conformance vs. Input Amplitude at 5.8 GHz,
OUT
Typical D evice, T
2.2
2.0
1.8
1.6
1.4
(V)
1.2
OUT
V
1.0
0.8
0.6
0.4
0.2
–65 –55 –45 –35 –25 –15 –5 5 15
Figure 7. V
and Log Conformance vs. Input Amplitude at 2.2 GHz,
OUT
PIN (dBm)
PIN (dBm)
= 1000 Ω
ADJ
Typical Device
2.0
1.6
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
–2.0
ERROR (dB)
04853-005
2.2
2.0
1.8
1.6
1.4
(V)
1.2
OUT
V
1.0
0.8
0.6
0.4
0.2
–65 –55 –45 –35 –25 –15 –5 5
Figure 8. V
and Log Conformance vs. Input Amplitude at 8 GHz,
OUT
PIN (dBm)
Typical Device
2.0
1.6
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
–2.0
2.0
1.6
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
–2.0
4.5
3.6
2.7
1.8
0.9
0
–0.9
–1.8
–2.7
–3.6
–4.5
ERROR (dB)
04853-006
ERROR (dB)
04853-007
ERROR (dB)
04853-008
Rev. 0 | Page 8 of 24
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