AD8312 Datasheet, PDF (1/13 Pages) Analog Devices – 100 MHz-2.7 GHz, 45 dB RF Log Detector

Preliminary Technical Data
FEATURES
Complete RF Detector Function
Typical Range : −45 dBm to 0 dBm re 50 Ω
Frequency Response from 100 MHz to 2.7 GHz
Temperature-Stable Linear-in-dB Response
Accurate to 2.7 GHz
Rapid Response: 70 ns to a 10 dB Step
Low Power: 12 mW at 2.7 V
APPLICATIONS
Cellular Handsets (GSM, CDMA, WCDMA)
RSSI and TSSI for Wireless Terminal Devices
Transmitter Power Measurement
PRODUCT DESCRIPTION
The AD8312 is a complete low cost subsystem for the
measurement of RF signals in the frequency range of 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 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
−40°C to +85°C.
100 MHz−2.7 GHz, 45 dB
RF Log Detector
AD8312
Its high sensitivity allows measurement 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 −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 approximately 16 MHz,
determines the lowest operating frequency. Thus, the source
may be dc-grounded.
The AD8312 output, called VOUT, 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 Applications section of this
data sheet for information on use in this mode. A capacitor may
be connected between the VOUT and CFLT pins when it is
desirable to increase the time interval over which averaging of
the input waveform occurs.
The AD8312 is available in a 6-lead wafer-level chip scale
package, 1.0 mm x 1.5 mm, and consumes 4.5 mA from a 2.7 V
to 5.5 V supply.
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
PrA
10/29/2004
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