ANALOG DEVICES AD8318-EP Service Manual
Logarithmic Detector/Controller
AD8318-EP
Rev. 0
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Fax: 781.461.3113 ©2012 Analog Devices, Inc. All rights reserved.
TEMP
SENSOR
GAIN
BIAS
SLOPE
DET DET DET DET
INHI
INLO
I V
VOUT
I V
VSET
CLPF
TEMP
VPSI ENBL TADJ VPSO
CMOPCMIP
10783-001
2.4
0
–65 10
P
IN
(dBm)
V
OUT
(V)
ERROR (dB)
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
6
–6
5
4
3
2
1
0
–1
–2
–3
–4
–5
–60 –55 –50 –45 –40 –35 –30 –25 –20 –15 –10 –5 0 5
10783-052
Enhanced Product
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 ns/12 ns (fall/rise)
Integrated temperature sensor
Small footprint LFCSP
Power-down feature: <1.5 mW at 5 V
Single-supply operation: 5 V @ 68 mA
Fabricated using high speed SiGe process
APPLICATIONS
RF transmitter PA setpoint control and level monitoring
RSSI measurement in base stations, WLAN, WiMAX, and
radars
GENERAL DESCRIPTION
1 MHz to 8 GHz, 70 dB
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
The AD8318-EP 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 is used in measurement or controller mode. The
AD8318-EP 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-EP has a 10 ns response time that enables
RF burst detection to beyond 45 MHz. The device provides
unprecedented logarithmic intercept stability vs. ambient
temperature conditions. A 2 mV/°C 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-EP can be configured to provide a control voltage
to a VGA, such as a power amplifier or a measurement output,
from Pin VOUT. Because the output can be used for controller
applications, wideband noise is minimal.
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 output to a magnitude
corresponding to VSET. The AD8318-EP provides 0 V to 4.9 V
output capability at the VOUT pin, suitable for controller
responsi bility 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.
Figure 2. Typical Logarithmic Response and Error vs. Input Amplitud e at 5.8 GHz
applications. As a measurement device, Pin VOUT is externally
connected to VSET to produce an output voltage, V
OUT
is a decreasing 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-EP is fabricated on a SiGe bipolar IC process and
is available in a 4 mm × 4 mm, 16-lead LFCSP. Performance is
specified over a temperature range of –55
o
C to +105oC.
Additional application and technical information can be found
in the AD8318 data sheet.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
, which
AD8318-EP Enhanced Product
TABLE OF CONTENTS
Features .............................................................................................. 1
ESD Caution...................................................................................6
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 6
REVISION HISTORY
7/12—Revision 0: Initial Version
Pin Configuration and Function Descriptions ..............................7
Typical Performance Characteristics ..............................................8
Outline Dimensions ....................................................................... 11
Ordering Guide .......................................................................... 11
Rev. 0 | Page 2 of 12
Enhanced Product AD8318-EP
POS
TAD J
−55°C < TA < +105°C
63 dB
±1 dB Dynamic Range
TA = 25°C
57 dB
TAD J
−55°C < TA < +105°C
63 dB
±1 dB Dynamic Range
TA = 25°C
57 dB
TAD J
−55°C < TA < +105°C
62 dB
±1 dB Dynamic Range
TA = 25°C
58 dB
SPECIFICATIONS
V
= 5 V, C
POS
Table 1.
Parameter Test Conditions/Comments Min Typ Max Unit
SIGNAL INPUT INTERFACE INHI (Pin 14) and INLO (Pin 15)
Specified Frequency Range
DC Common-Mode Voltage V
MEASUREMENT MODE VOUT (Pin 6) shorted to VSET (Pin 7), sinusoidal
f = 900 MHz R
Input Impedance 957||0.71 Ω||pF
±3 dB Dynamic Range TA = 25°C 65 dB
Maximum Input Level ±1 dB error −1 dBm
Minimum Input Level ±1 dB error −58 dBm
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
25°C ≤ TA ≤ 105°C 0.0071 dB/°C
−55°C ≤ TA ≤ +25°C 0.0031 dB/°C
f = 1.9 GHz R
Input Impedance 523||0.68 Ω||pF
±3 dB Dynamic Range TA = 25°C 65 dB
= 220 pF, TA = 25°C, 52.3 Ω termination resistor at INHI, unless otherwise noted.
LPF
0.001 8 GHz
input signal
= 500 Ω
= 500 Ω
– 1.8 V
Maximum Input Level ±1 dB error −2 dBm
Minimum Input Level ±1 dB error −59 dBm
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
25°C ≤ TA ≤ 105°C 0.0056 dB/°C
−55°C ≤ TA ≤ +25°C 0.0004 dB/°C
f = 2.2 GHz R
= 500 Ω
Input Impedance 391||0.66 Ω||pF
±3 dB Dynamic Range TA = 25°C 65 dB
Maximum Input Level ±1 dB error −2 dBm
Minimum Input Level ±1 dB error −60 dBm
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
25°C ≤ TA ≤ 105°C 0.0052 dB/°C
−55°C ≤ TA ≤ +25°C 0.0034 dB/°C
Rev. 0 | Page 3 of 12
AD8318-EP Enhanced Product
TAD J
±1 dB Dynamic Range
TA = 25°C
58 dB
TADJ
±1 dB Dynamic Range
TA = 25°C
57 dB
TAD J
Maximum Input Level
±3 dB error
3
dBm
SET
1
SET
SET
Video Bandwidth (or Envelope Bandwidth)
45 MHz
NOISE
LPF
Parameter Test Conditions/Comments Min Typ Max Unit
f = 3.6 GHz R
Input Impedance 119||0.7 Ω||pF
±3 dB Dynamic Range TA = 25°C 70 dB
−55°C < TA < +105°C 61 dB
Maximum Input Level ±1 dB error −2 dBm
Minimum Input Level ±1 dB error –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 ≤ TA ≤ 105°C 0.0012 dB/°C
−55°C ≤ TA ≤ +25°C 0.009 dB/°C
f = 5.8 GHz R
Input Impedance 33||0.59 Ω||pF
±3 dB Dynamic Range TA = 25°C 70 dB
−55°C < TA < +105°C 62 dB
Maximum Input Level ±1 dB error −1 dBm
Minimum Input Level ±1 dB error −58 dBm
Slope −24.3 mV/dB
Intercept 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 ≤ TA ≤ 105°C 0.019 dB/°C
−55°C ≤ TA ≤ +25°C 0.0096 dB/°C
f = 8.0 GHz R
±3 dB Dynamic Range TA = 25°C 60 dB
−55°C < TA < +105°C 58 dB
= 51 Ω
= 1000 Ω
= 500 Ω
Minimum Input Level ±3 dB error −55 dBm
Slope −23 mV/dB
Intercept 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 ≤ TA ≤ 105°C 0.032 dB/°C
−55°C ≤ TA ≤ +25°C 0.0078 dB/°C
OUTPUT INTERFACE VOUT (Pin 6)
Voltage Swing V
V
Output Current Drive V
Small Signal Bandwidth PIN = −10 dBm; from CLPF to VOUT 60 MHz
Output Noise PIN = 2.2 GHz; −10 dBm, f
Fall Time PIN = Off to −10 dBm, 90% to 10% 10 ns
Rise Time PIN = −10 dBm to off, 10% to 90% 12 ns
= 0 V; PIN = −10 dBm, no load
= 2.1 V; PIN = −10 dBm, no load
1
4.9 V
25 mV
= 1.5 V; PIN = −50 dBm 60 mA
= 100 kHz, C
Rev. 0 | Page 4 of 12
= 220 pF 90 nV/√Hz
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