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50 MHz to 4 GHz
TruPwr
Detector
ADL5501
FEATURES
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.
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Tel: 781.329.4700
Fax: 781.461.3113
2006 Analog Devices, Inc. All rights reserved.
www.analog.com
True rms response
Excellent temperature stability
Up to 30 dB input dynamic range at 4 GHz
50 Ω input impedance
1.25 V rms, 15 dBm, maximum input
Single-supply operation: 2.7 V to 5.5 V
Low power: 3.3 mW at 3 V supply
RoHS-compliant
APPLICATIONS
Measurement of CDMA2000-, W-CDMA-, and QPSK-/QAM-
based OFDM, and other complex modulation waveforms
RF transmitter or receiver power measurement
5
0.03
0.1
1
–25
–20
–15
–10
–5
0
5
10
15
O
INPUT (dBm)
0
Figure 1. Output vs. Input Level, Supply 3 V, Frequency 1.9 GHz
GENERAL DESCRIPTION
The ADL5501 is a mean-responding power detector for use
in high frequency receiver and transmitter signal chains from
50 MHz to 4 GHz. It is easy to apply, requiring only a single
supply between 2.7 V and 5.5 V and a power supply decoupling
capacitor. The input is internally ac-coupled and has a nominal
input impedance of 50 Ω. The output is a linear-responding dc
voltage with a conversion gain of 6.3 V/V rms at 900 MHz.
The ADL5501 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-, CDMA2000-, W-CDMA-, and QPSK-/QAM-
based OFDM waveforms. The on-chip modulation filter provides
adequate averaging for most waveforms.
The on-chip, 100 Ω series resistance at the output, combined
with an external shunt capacitor, creates a low-pass filter response
that reduces the residual ripple in the dc output voltage. For more
complex waveforms, an external capacitor at the FLTR pin can
be used for supplementary signal demodulation.
The ADL5501 offers excellent temperature stability across a
30 dB range and near 0 dB measurement error across temperature
over the top portion of the dynamic range. In addition to its
temperature stability, the ADL5501 offers low process variations
that further reduce calibration complexity.
The ADL5501 operates from 40°C to +85°C and is available in
a small 6-lead SC-70 package. It is fabricated on a proprietary
high f
T
silicon bipolar process.
FUNCTIONAL BLOCK DIAGRAM
RFIN
BUFFER
VPOS
VRMS
COMM
EAMP
x
2
x
2
i
i
TRANS-
ADL5501
100
FLTR
BAND-GAP
ENBL
INTERNAL FILTER
0
Figure 2.