50 Hz to 6 GHz

Preliminary Technical Data

AD8363

Rev. PrB

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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

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.