LF to 2.5 GHz
TruPwr™ Detector
AD8361
FEATURES
Calibrated rms response
Excellent temperature stability
Up to 30 dB input range at 2.5 GHz
700 mV rms, 10 dBm, re 50 Ω maximum input
±0.25 dB linear response up to 2.5 GHz
Single-supply operation: 2.7 V to 5.5 V
Low power: 3.3 mW at 3 V supply
Rapid power-down to less than 1 µA
FUNCTIONAL BLOCK DIAGRAMS
VPOS
RFIN
χ
2
TRANS-
CONDUCTANCE
CELLS
i
INTERNAL FILTER
FLTR
AD8361
χ
2
i
ERROR
AMP
×
7.5
BUFFER
ADD
OFFSET
VRMS
PWDN
BAND-GAP
REFERENCE
SREF
COMM
IREF
01088-C-002
01088-C-003
APPLICATIONS
Measurement of CDMA, W-CDMA, QAM, other complex
modulation waveforms
RF transmitter or receiver power measurement
Figure 2. 8-Lead MSOP
VPOS
RFIN
GENERAL DESCRIPTION
The AD8361 is a mean-responding power detector for use in
high frequency receiver and transmitter signal chains, up to
2.5 GHz. It is very easy to apply. It requires a single supply only
between 2.7 V and 5.5 V, a power supply decoupling capacitor,
and an input coupling capacitor in most applications. The
output is a linear-responding dc voltage with a conversion gain
of 7.5 V/V rms. An external filter capacitor can be added to
increase the averaging time constant.
3.0
2.8
2.6
2.4
2.2
2.0
INTERNAL
REFERENCE MODE
SUPPLY
REFERENCE MODE
χ
2
TRANS-
CONDUCTANCE
CELLS
i
INTERNAL FILTER
FLTR
AD8361
χ
2
i
ERROR
AMP
×
7.5
BUFFER
VRMS
PWDN
BAND-GAP
REFERENCE
COMM
IREF
Figure 3. 6-Lead SOT-23
V rms (Volts)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.0
01088-C-001
The AD8361 is intended for true power measurement of simple
and complex waveforms. The device is particularly useful for
measuring high crest-factor (high peak-to-rms ratio) signals,
such as CDMA and W-CDMA.
GROUND
REFERENCE MODE
The AD8361 has three operating modes to accommodate a
variety of analog-to-digital converter requirements:
1.
2.
3.
Ground reference mode, in which the origin is zero.
Internal reference mode, which offsets the output 350 mV
above ground.
Supply reference mode, which offsets the output to V
S
/7.5.
0.2
0
0.1
0.2
0.3
RFIN (V rms)
0.4
0.5
Figure 1. Output in the Three Reference Modes, Supply 3 V, Frequency 1.9 GHz
(6-Lead SOT-23 Package Ground Reference Mode Only)
The AD8361 is specified for operation from −40°C to +85°C
and is available in 8-lead MSOP and 6-lead SOT-23 packages. It
is fabricated on a proprietary high f
T
silicon bipolar process.
Rev. C
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
www.analog.com
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
AD8361
TABLE OF CONTENTS
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Typical Performance Characteristics ............................................. 6
Circuit Description......................................................................... 11
Applications..................................................................................... 12
Output Reference Temperature Drift Compensation ........... 16
Evaluation Board ............................................................................ 21
Characterization Setups............................................................. 23
Outline Dimensions ....................................................................... 24
Ordering Guide .......................................................................... 24
REVISION HISTORY
8/04—Data Sheet Changed from Rev. B to Rev. C.
Changed Trimpots to Trimmable Potentiometers .........Universal
Changes to Specifications ................................................................ 3
Changed Using the AD8361 Section Title to Applications ....... 12
Changes to Figure 43...................................................................... 14
Changes to Ordering Guide .......................................................... 24
Updated Outline Dimensions ....................................................... 24
2/01—Data Sheet Changed from Rev. A to Rev. B.
Rev. C | Page 2 of 24
AD8361
SPECIFICATIONS
T
A
= 25°C, V
S
= 3 V, f
RF
= 900 MHz, ground reference output mode, unless otherwise noted.
Table 1.
Parameter
SIGNAL INPUT INTERFACE
Frequency Range
1
Linear Response Upper Limit
Condition
(Input RFIN)
V
S
= 3 V
Equivalent dBm, re 50 Ω
V
S
= 5 V
Equivalent dBm, re 50 Ω
(Input RFIN to Output V rms)
7.5
f
RF
= 100 MHz, V
S
= 5 V
Error Referred to Best Fit Line
3
CW Input, −40°C < T
A
< +85°C
CW Input, −40°C < T
A
< +85°C
CW Input, −40°C < T
A
< +85°C
CW Input, V
S
= 5 V, −40°C < T
A
< +85°C
Internal Reference Mode
Supply Reference Mode, V
S
= 3.0 V
Supply Reference Mode, V
S
= 5.0 V
5.5 dB Peak-to-Average Ratio (IS95 Reverse Link)
12 dB Peak-to-Average Ratio (W-CDMA 4 Channels)
18 dB Peak-to-Average Ratio (W-CDMA 15 Channels)
Inferred from Best Fit Line
3
0 V at SREF, V
S
at IREF
f
RF
= 100 MHz, V
S
= 5 V
0 V at SREF, IREF Open
f
RF
= 100 MHz, V
S
= 5 V
3 V at IREF, 3 V at SREF
V
S
at IREF, V
S
at SREF
f
RF
= 100 MHz, V
S
= 5 V
2.7 ≤ V
S
≤ 5.5 V, −40°C < T
A
< +85°C
2.7 ≤ V
S
≤ 5.5 V, −40°C < T
A
< +85°C
2 pF at FLTR Pin, 224 mV rms at RFIN
100 nF at FLTR Pin, 224 mV rms at RFIN
6.5
14
23
26
30
1
1
1.5
0.2
1.0
1.2
0
−50
350
300
400
V
S
/7.5
590
V
S
− 0.5
0.1
5
320
<1
2.7
1.1
<1
10 × V
S
5.5
750
500
+150
8.5
V/V rms
V/V rms
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
V
mV
mV
mV
mV
V
mV
V
V
µs
µs
µA
V
mA
µA
µA
Min
Typ
Max
2.5
390
4.9
660
9.4
225||1
Unit
GHz
mV rms
dBm
mV rms
dBm
Ω||pF
Input Impedance
2
RMS CONVERSION
Conversion Gain
Dynamic Range
±0.25 dB Error
4
±1 dB Error
±2 dB Error
Intercept-Induced Dynamic
Range Reduction
5, 6
Deviation from CW Response
OUTPUT INTERCEPT
5
Ground Reference Mode (GRM)
Internal Reference Mode (IRM)
Supply Reference Mode (SRM)
POWER-DOWN INTERFACE
PWDN HI Threshold
PWDN LO Threshold
Power-Up Response Time
PWDN Bias Current
POWER SUPPLIES
Operating Range
Quiescent Current
Power-Down Current
−40°C < T
A
< +85°C
0 mV rms at RFIN, PWDN Input LO
7
GRM or IRM, 0 mV rms at RFIN, PWDN Input HI
SRM, 0 mV rms at RFIN, PWDN Input HI
1
2
Operation at arbitrarily low frequencies is possible; see Applications section.
Figure 17 and Figure 47 show impedance versus frequency for the MSOP and SOT-23, respectively.
3
Calculated using linear regression.
4
Compensated for output reference temperature drift; see Applications section.
5
SOT-23-6L operates in ground reference mode only.
6
The available output swing, and hence the dynamic range, is altered by both supply voltage and reference mode; see Figure 39 and Figure 40.
7
Supply current is input level dependant; see Figure 16.
Rev. C | Page 3 of 24
AD8361
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage V
S
SREF, PWDN
IREF
RFIN
Equivalent Power, re 50 Ω
Internal Power Dissipation
1
6-Lead SOT-23
8-Lead MSOP
Maximum Junction Temperature
Operating Temperature Range
Storage Temperature Range
Lead Temperature Range
(Soldering 60 sec)
Rating
5.5 V
0 V, V
S
V
S
− 0.3 V, V
S
1 V rms
13 dBm
200 mW
170 mW
200 mW
125°C
−40°C to +85°C
−65°C to +150°C
300°C
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.
1
Specification is for the device in free air.
6-Lead SOT-23: θ
JA
= 230°C/W; θ
JC
= 92°C/W.
8-Lead MSOP: θ
JA
= 200°C/W; θ
JC
= 44°C/W.
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.
Rev. C | Page 4 of 24
AD8361
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
VPOS
1
IREF
2
RFIN
3
PWDN
4
8
SREF
VRMS
FLTR
COMM
01088-C-004
AD8361
TOP VIEW
(Not to Scale)
VRMS
1
6
VPOS
7
6
5
AD8361
COMM
2
FLTR
3
01088-C-005
5
RFIN
TOP VIEW
(Not to Scale)
4
PWDN
Figure 4. 8-Lead MSOP
Figure 5. 6-Lead SOT-23
Table 3. Pin Function Descriptions
Pin No.
MSOP
1
2
3
4
Pin No.
SOT-23
6
N/A
5
4
Mnemonic
VPOS
IREF
RFIN
PWDN
Description
Supply Voltage Pin. Operational range 2.7 V to 5.5 V.
Output Reference Control Pin. Internal reference mode enabled when pin is left open; otherwise, this
pin should be tied to VPOS. Do not ground this pin.
Signal Input Pin. Must be driven from an ac-coupled source. The low frequency real input impedance
is 225 Ω.
Power-Down Pin. For the device to operate as a detector, it needs a logical low input (less than
100 mV). When a logic high (greater than V
S
− 0.5 V) is applied, the device is turned off and the supply
current goes to nearly zero (ground and internal reference mode less than 1 µA, supply reference
mode V
S
divided by 100 kΩ).
Device Ground Pin.
By placing a capacitor between this pin and VPOS, the corner frequency of the modulation filter is
lowered. The on-chip filter is formed with 27 pF||2 kΩ for small input signals.
Output Pin. Near rail-to-rail voltage output with limited current drive capabilities. Expected load
>10 kΩ to ground.
Supply Reference Control Pin. To enable supply reference mode, this pin must be connected to VPOS;
otherwise, it should be connected to COMM (ground).
5
6
7
8
2
3
1
N/A
COMM
FLTR
VRMS
SREF
Rev. C | Page 5 of 24
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