Preliminary Technical Data
FEATURES
Accurate RMS-to-DC conversion from 50 Hz to 6 GHz
Single ended input dynamic range of >50 dB
Waveform and modulation independent, such as
WiMAX/GSM/CDMA/WCDMA/TDMA
Linear-in-decibels output, scaled 50 mV/dB
Log conformance error of <0.3 dB
Temperature stability of <±0.5 dB
Voltage supply range of 4.5 V to 5.5 V
Operating temperature range of −40°C to +125°C
Power-down capability
50 Hz to 6 GHz
50 dB TruPwr
™
Detector
AD8363
APPLICATIONS
Power amplifier linearization/control loops
Transmitter power controls
Transmitter signal strength indication (TSSI)
RF instrumentation
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
GENERAL DESCRIPTION
The AD8363 is a true RMS responding power detector that has
more than 50 dB measurement range when driven with a
single-ended 50
Ω
source. The device provides a solution in a
variety of high frequency communication systems, and in
instrumentation, requiring an accurate response to signal
power. The AD8363 is easy to use with its single-ended 50
Ω
input, only requiring a single 5 V supply, and a few capacitors.
The AD8363 can operate from arbitrarily low frequencies to 6
GHz and can accept inputs that have RMS values from less than
-50 dBm to at least 0 dBm, with large crest factors, exceeding
the requirements for accurate measurement of WiMAX,
WCDMA, and CDMA signals.
The AD8363 can determine the true power of a high frequency
signal having a complex low frequency modulation envelope, or
can be used as a simple low frequency RMS voltmeter. The
high-pass corner generated by its internal offset-nulling loop
can be lowered by a capacitor added on the CHPF pin.
Used as a power measurement device, VOUT is connected to
VSET. The output is then proportional to the logarithm of the
RMS value of the input. In other words, the reading is
presented directly in decibels and is conveniently scaled 1 V per
decade, or 50 mV/dB; other slopes are easily arranged. In
controller mode, the voltage applied to VSET determines the
power level required at the input to null the deviation from the
set point. The output buffer can provide high load currents.
The AD8363 has 1.5 mW power consumption when powered
down by a logic high applied to pin 1, TCM2. It powers up
within about 30 μs to its nominal operating current of 60 mA at
25°C. The AD8363 is supplied in a 4 mm x 4 mm, 16-lead
LFCSP for operation over the temperature range of −40°C to
+125°C. An evaluation board is available.
Rev. PrB
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