AD8312_05 Datasheet, PDF (1/20 Pages) Analog Devices – 50 MHz to 3.5 GHz, 45 dB RF Detector

50 MHz to 3.5 GHz, 45 dB
RF Detector
AD8312
FEATURES
Complete RF detector function
Typical range: −45 dBm to 0 dBm, re 50 Ω
Frequency response from 50 MHz to 3.5 GHz
Temperature-stable linear-in-dB response
Accurate to 3.5 GHz
Rapid response: 85/120 ns (rise/fall)
Low power: 12 mW at 2.7 V
APPLICATIONS
Cellular handsets (GSM, CDMA, WCDMA)
RSSI and TSSI for wireless terminal devices
Transmitter power measurement
GENERAL DESCRIPTION
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 1.3 pF. This high-
pass coupling, with a corner at approximately 16 MHz,
determines the lowest operating frequency. Therefore, the
source may be dc grounded.
The AD8312 output, VOUT, increases from close to ground to
about 1.2 V because the input signal level increases from
1.25 mV to 224 mV. 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 a complete, low cost subsystem for the
measurement of RF signals in the frequency range of 50 MHz to
3.5 GHz. It has a typical dynamic range of 45 dB and is 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.
The AD8312 is available in a 6-ball, 1.0 mm × 1.5 mm, wafer-
level chip scale package and consumes 4.2 mA from a 2.7 V to
5.5 V supply.
FUNCTIONAL BLOCK DIAGRAM
RFIN
DET
DET
DET
DET
CFLT
V-I
–
+
I-V
DET
10dB
10dB
10dB
10dB
BAND-GAP
REFERENCE
VSET
VOUT
VPOS
COMM
OFFSET
COMPENSATION
AD8312
Figure 1.
Rev. 0
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