1 MHz – 8 GHz, 60 dB
Logarithmic Detector/Controller
AD8318
FEATURES
Wide bandwidth: 1 MHz to 8 GHz
High accuracy: ±1.0 dB over 55 dB range (f < 5.8 GHz)
Stability over temperature: ±0.5 dB
Low noise measurement/controller output VOUT
Pulse response time 10/12 ns (fall/rise)
Integrated temperature sensor
Small footprint CSP package
Power-down feature: <1.5 mW at 5 V
Single-supply operation: 5V @ 68 mA
Fabricated using high speed SiGe process
APPLICATIONS
RF transmitter PA setpoint control and level monitoring
RSSI measurement in base stations, WLAN, radar
GENERAL DESCRIPTION
The AD8318 is a demodulating logarithmic amplifier, capable of
accurately converting an RF input signal to a corresponding
decibel-scaled output voltage. It employs the progressive
compression technique over a cascaded amplifier chain, each
stage of which is equipped with a detector cell. The device can be
used in measurement or controller mode. The AD8318
maintains accurate log conformance for signals of 1 MHz to
6 GHz and provides useful operation to 8 GHz. The input range
is typically 60 dB (re: 50
) with error less than
±
1 dB. The
AD8318 has a 10 ns response time that enables RF burst
detection to beyond 60 MHz. The device provides
unprecedented logarithmic intercept stability versus ambient
temperature conditions. A 2 mV/K slope temperature sensor
output is also provided for additional system monitoring. A
single supply of +5 V is required. Current consumption is
typically 68 mA. Power consumption decreases to <1.5 mW
when the device is disabled.
Rev.
0
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infringements of patents or other rights of third parties that may result from its
use. Specifications subject to change without notice. No license is granted by
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owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703
The AD8318 can be configured to provide a control voltage to a pin VOUT. Since the output can be used for controller
Figure 1.
wideband noise. In this mode, the setpoint control voltage is
applied to VSET. The feedback loop through an RF
.
VOUT pin, suitable for controller applications. As a
linear-in-dB function of the RF input signal amplitude.
VSET interface. The intercept is +20 dBm (re: 50
input) using the INHI input. These parameters are very
stable against supply and temperature variations.
C.