Datasheet AD8314 (Analog Devices)

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100 MHz to 2.7 GHz, 45 dB RF Detector/Control er Data Sheet AD8314 FEATURES
For convenience, the signal is internally ac-coupled, using a
Complete RF detector/controller function
5 pF capacitor to a load of 3 kΩ in shunt with 2 pF. This high-
Typical range:−58 dBV to −13 dBV
pass coupling, with a corner at approximately 16 MHz,
−45 dBm to 0 dBm, re 50 Ω
determines the lowest operating frequency. Therefore, the
Frequency response from 100 MHz to 2.7 GHz
source can be dc grounded.
Temperature-stable linear-in-dB response
The AD8314 provides two voltage outputs. The first, V_UP,
Accurate to 2.7 GHz
increases from close to ground to about 1.2 V as the input signal
Rapid response: 70 ns to a 10 dB step
level increases from 1.25 mV to 224 mV. This output is intended
Low power: 12 mW at 2.7 V
for use in measurement mode. Consult the Applications section
Power down to 20 µA
for information on this mode. A capacitor can be connected
APPLICATIONS
between the V_UP and FLTR pins when it is desirable to increase the time interval over which averaging of the input
Cellular handsets (TDMA, CDMA , GSM)
waveform occurs.
RSSI and TSSI for wireless terminal devices Transmitter power measurement and control
The second output, V_DN, is an inversion of V_UP but with twice the slope and offset by a fixed amount. This output starts
GENERAL DESCRIPTION
at about 2.25 V (provided the supply voltage is ≥3.3 V) for the The AD8314 is a complete low cost subsystem for the minimum input and falls to a value close to ground at the measurement and control of RF signals in the frequency range maximum input. This output is intended for analog control of 100 MHz to 2.7 GHz, with a typical dynamic range of 45 dB, loop applications. A setpoint voltage is applied to VSET, and intended for use in a wide variety of cellular handsets and other V_DN is then used to control a VGA or power amplifier. Here wireless devices. It provides a wider dynamic range and better again, an external filter capacitor can be added to extend the accuracy than possible using discrete diode detectors. In averaging time. Consult the Applications section for particular, its temperature stability is excellent over the full information on this mode. operating range of −40°C to +85°C. The AD8314 is available in 8-lead MSOP and 8-lead LFCSP Its high sensitivity allows control at low power levels, thus packages and consumes 4.5 mA from a 2.7 V to 5.5 V supply. reducing the amount of power that needs to be coupled to the When powered down, the typical sleep current is 20 µA. detector. It is essentially a voltage-responding device, with a typical 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.
FUNCTIONAL BLOCK DIAGRAM FLTR V-I VSET – + I-V V_UP DET DET DET DET DET – X2 V_DN RFIN + 10dB 10dB 10dB 10dB VPOS BAND GAP OFFSET AD8314 REFERENCE ENBL COMPENSATION
001
COMM (PADDLE)
01086- Figure 1.
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION INVERTED OUTPUT APPLICATIONS BASIC CONNECTIONS TRANSFER FUNCTION IN TERMS OF SLOPE AND INTERCEPT dBV VS. dBm FILTER CAPACITOR OPERATING IN CONTROLLER MODE POWER-ON AND ENABLE GLITCH INPUT COUPLING OPTIONS INCREASING THE LOGARITHMIC SLOPE IN MEASUREMENT MODE EFFECT OF WAVEFORM TYPE ON INTERCEPT MOBILE HANDSET POWER CONTROL EXAMPLES OPERATION AT 2.7 GHz USING THE LFCSP PACKAGE EVALUATION BOARD OUTLINE DIMENSIONS ORDERING GUIDE