ANALOG DEVICES AD8317 Product Data Sheet

1 MHz to 10 GHz, 55 d B Log Detector/Controller

AD8317 FEATURES FUNCTIONAL BLOCK DIAGRAM

TADJVPOS

Wide bandwidth: 1 MHz to 10 GHz High accuracy: ±1.0 d B over temperature

SLOPE

55 d B dynamic range up to 8 GHz ± 3 d B error BIAS VSET

Stability over temperature: ±0.5 d B Low noise measurement/controller output, VOUT VOUT Pulse response time: 6 ns/10 ns (fall/rise) DET DET DET DET

Small footprint, 2 mm × 3 mm LFCSP CLPF

Supply operation: 3.0 V to 5.5 V @ 22 m A

Fabricated using high speed Si Ge process

APPLICATIONS COMM Figure 1.

RF transmitter PA setpoint control and level monitoring Power monitoring in radio link transmitters RSSI measurement in base stations, WLANs, Wi MAX, and radars

GENERAL DESCRIPTION

The AD8317 is a demodulating logarithmic amplifier, capable The feedback loop through an RF amplifier is closed via VOUT, of accurately converting an RF input signal to a corresponding the output of which regulates the output of the amplifier to a decibel-scaled output. It employs the progressive compression magnitude corresponding to VSET. The AD8317 provides 0 V to

technique over a cascaded amplifier chain, each stage of which (VPOS − 0.1 V) output capability at the VOUT pin, suitable for is equipped with a detector cell. The device can be used in either controller applications. As a measurement device, VOUT is measurement or controller modes. The AD8317 maintains externally connected to VSET to produce an output voltage, accurate log conformance for signals of 1 MHz to 8 GHz and VOUT, that is a decreasing linear-in-d B function of the RF input

provides useful operation to 10 GHz. The input dynamic range signal amplitude.

is typically 55 d B (re: 50 Ω) with less than ±3 d B error. The

The logarithmic slope is −22 m V/d B, determined by the VSET

AD8317 has 6 ns/10 ns response time (fall time/rise time) that

interface. The intercept is 15 d Bm (re: 50 Ω, CW input) using

enables RF burst detection to a pulse rate of beyond 50 MHz.

the INHI input. These parameters are very stable against supply

The device provides unprecedented logarithmic intercept stability

and temperature variations.

vs. ambient temperature conditions. A supply of 3.0 V to 5.5 V

The AD8317 is fabricated on a Si Ge bipolar IC process and is

is required to power the device. Current consumption is typically

available in a 2 mm × 3 mm, 8-lead LFCSP with an operating

22 m A, and it decreases to 200 μA when the device is disabled.

temperature range of −40°C to +85°C.

The AD8317 can be configured to provide a control voltage to a power amplifier or a measurement output from the VOUT pin. Because the output can be used for controller applications, special attention has been paid to minimize wideband noise. In this 1- mode, the setpoint control voltage is applied to the VSET pin.

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