AD8314ARM

AD8314ARM FEATURES

Complete RF detector/controller functionTypical range:−58 dBV to −13 dBV−45 dBm to 0 dBm, re 50 ΩFrequency response from 100 MHz to 2.7 GHzTemperature-stable linear-in-dB responseAccurate to 2.7 GHzRapid response: 70 ns to a 10 dB stepLow power: 12 mW at 2.7 VPower down to 20 µA

AD8314ARM GENERAL DESCRIPTION

The AD8314 is a complete low cost subsystem for themeasurement and control of RF signals in the frequency rangeof 100 MHz to 2.7 GHz, with a typical dynamic range of 45 dB,intended for use in a wide variety of cellular handsets and otherwireless devices. It provides a wider dynamic range and betteraccuracy than possible using discrete diode detectors. Inparticular, its temperature stability is excellent over the fulloperating range of −40°C to +85°C.Its high sensitivity allows control at low power levels, thusreducing the amount of power that needs to be coupled to thedetector. It is essentially a voltage-responding device, with atypical signal range of 1.25 mV to 224 mV rms or –58 dBV to−13 dBV. This is equivalent to −45 dBm to 0 dBm, re 50 Ω.For convenience, the signal is internally ac-coupled, using a5 pF capacitor to a load of 3 kΩ in shunt with 2 pF. This high-pass coupling, with a corner at approximately 16 MHz,determines the lowest operating frequency. Therefore, thesource can be dc grounded.The AD8314 provides two voltage outputs. The first, V_UP,increases from close to ground to about 1.2 V as the input signallevel increases from 1.25 mV to 224 mV. This output is intendedfor use in measurement mode. Consult the Applications sectionfor information on this mode. A capacitor can be connectedbetween the V_UP and FLTR pins when it is desirable toincrease the time interval over which averaging of the inputwaveform occurs.The second output, V_DN, is an inversion of V_UP but withtwice the slope and offset by a fixed amount. This output startsat about 2.25 V (provided the supply voltage is ≥3.3 V) for theminimum input and falls to a value close to ground at themaximum input. This output is intended for analog controlloop applications. A setpoint voltage is applied to VSET, andV_DN is then used to control a VGA or power amplifier. Hereagain, an external filter capacitor can be added to extend theaveraging time. Consult the Applications section forinformation on this mode.The AD8314 is available in 8-lead MSOP and 8-lead LFCSPpackages and consumes 4.5 mA from a 2.7 V to 5.5 V supply.When powered down, the typical sleep current is 20 µA.

AD8314ARM APPLICATIONS

Cellular handsets (TDMA, CDMA , GSM)RSSI and TSSI for wireless terminal devicesTransmitter power measurement and control