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
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
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