800 MHz to 3800 MHz

Crest Factor Detector

Preliminary Technical Data

ADL5502

Rev. PrD (04/20/2008)

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FEATURES

True rms response detector

Envelope output with peak hold option

Excellent temperature stability

±0.25 dB rms detection accuracy vs. temperature

±0.25 dB envelope detection accuracy vs. temperature;

over the top 15 dB of the input range

Over 30 dB input power dynamic range, inclusive of crest

factor, up to 3.8 GHz

RF bandwidths from 800 MHz to 3.8 GHz

Envelope bandwidths of 10 MHz

500 Ω input impedance

Single-supply operation: 2.7 V to 3.5 V

Low power: 5 mA at 3 V supply

RoHS compliant

APPLICATIONS

Power and envelope measurement of W-CDMA, CDMA2000,

and QPSK-/QAM-based OFDM, and other complex

modulation waveforms

RF transmitter or receiver power and envelope measurement

Figure 1.

GENERAL DESCRIPTION

The ADL5502 is a mean-responding power detector in

combination with an envelope detector to accurately determine

the crest factor of a modulated signal. It can be used in high

frequency receiver and transmitter signal chains from 800 MHz

to 3.8 GHz with envelope bandwidths over 10 MHz. Requiring

only a single supply between 2.7 V and 3.5 V, the detector draws

less than 5 mA. The input is internally ac-coupled and has a

nominal input impedance of 500 Ω.

The rms output is a linear-responding dc voltage with a

conversion gain of 2.0 V/Vrms at 900 MHz. The envelope

output with a conversion gain of 1.4 V/V can be toggled

between real-time envelope measurement or peak hold with less

than TBD mV droop in over 200 μS.

The ADL5502 is a highly accurate, easy to use means of

determining the peak to average value of complex waveforms.

It can be used for crest factor measurements of both simple and

complex waveforms, but is particularly useful for measuring

high crest factor (high peak-to-rms ratio) signals, such as

CDMA2000, W-CDMA, and QPSK/QAM-based OFDM

waveforms. The peak hold function allows the capture of short

peaks in the envelope with lower sampling rate ADC’s.

The crest factor detector operates from −40°C to +85°C and is

available in an 8-ball, 1.5 mm × 1.5 mm wafer-level chip scale