AD8314 Datasheet, PDF (1/16 Pages) Analog Devices – 100 MHz-2500 MHz 45 dB RF Detector/Controller

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100 MHz–2500 MHz 45 dB
RF Detector/Controller
AD8314
FEATURES
Complete RF Detector/Controller Function
Typical Range –58 dBV to –13 dBV
–45 dBm to 0 dBm re 50 ⍀
Frequency Response from 100 MHz to 2.5 GHz
Temperature-Stable Linear-in-dB Response
Accurate to 2.5 GHz
Rapid Response: 70 ns to a 10 dB Step
Low Power: 12 mW at 2.7 V
Power-Down to 20 ␮A
APPLICATIONS
Cellular Handsets (TDMA, CDMA, GSM)
RSSI and TSSI for Wireless Terminal Devices
Transmitter Power Measurement and Control
PRODUCT DESCRIPTION
The AD8314 is a complete low-cost subsystem for the mea-
surement and control of RF signals in the frequency range
0.1 GHz–2.5 GHz, with a typical dynamic range of 45 dB,
intended for use in a wide variety of cellular handsets and other
wireless devices. It provides a wider dynamic range and better
accuracy than possible using discrete diode detectors. In particular,
its temperature stability is excellent over the full operating range of
–30°C to +85°C.
Its high sensitivity allows control at low power levels, thus
reducing the amount of power that needs to be coupled to the
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.
For convenience, the signal is internally ac-coupled, using a 5 pF
capacitor to a load of 3 kΩ in shunt with 2 pF. This high-pass
coupling, with a corner at 16 MHz, determines the lowest oper-
ating frequency. Thus, the source may be dc-grounded.
The AD8314 provides two voltage outputs. The first, called
V_UP, increases from close to ground to about 1.2 V as the
input signal level increases from 1.25 mV to 224 mV. This output
is intended for use in measurement mode. Consult the Appli-
cations section of this data sheet for information on use in this
mode. A capacitor may be connected between the V_UP and
FLTR pins when it is desirable to increase the time interval over
which averaging of the input waveform occurs.
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
at about 2.25 V (provided the supply voltage is ≥3.3 V) for
the minimum input and falls to a value close to ground at the
maximum input. This output is intended for analog control
loop applications. A setpoint voltage is applied to VSET and
V_DN is then used to control a VGA or power amplifier. Here
again, an external filter capacitor may be added to extend the
averaging time. Consult the Applications section of this data
sheet for information on use in this mode.
The AD8314 is available in a micro_SOIC package and con-
sumes 4.5 mA from a 2.7 V to 5.5 V supply. When powered
down, the typical sleep current is 20 µA.
RFIN
COMM
(PADDLE)
FUNCTIONAL BLOCK DIAGRAM
FLTR
V-I
VSET
DET
DET
DET
DET
DET
I-V
V UP
10dB
10dB
10dB
10dB
X2
V DN
OFFSET
COMP'N
AD8314
BAND-GAP
REFERENCE
VPOS
ENBL
REV. 0
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