AD8311 Analog Devices Data Handbook/Manual

50 d B GSM PA Controller

AD8311

Its high sensitivity allows control at low signal levels, thus

FEATURES

reducing the amount of power that needs to be coupled to the

Complete RF detector/controller function

detector. For convenience, the signal is internally ac-coupled.

>50 d B range at 0.9 GHz (−48 d Bm to +3 d Bm re 50 Ω)

This high-pass coupling, with a corner at approximately

Accurate scaling from 0.1 GHz to 2.5 GHz

0.016 GHz, determines the lowest operating frequency. Thus,

Temperature-stable linear-in-d B response

the source can be dc-grounded.

Log slope of 23 m V/d B, intercept at −60 d Bm at 0.9 GHz True integration function in control loop The AD8311 provides a voltage output, VAPC, which has the Low power: 20 m W at 2.7 V voltage range and current drive to directly connect to the gain

control pin of most handset power amplifiers. VAPC can swing from 300 m V above ground to within 200 m V below the supply

APPLICATIONS

voltage. Load currents of up to 6 m A can be supported.

Single, dual, and triple band mobile handset (GSM, DCS, EDGE)

The setpoint control input is applied to pin VSET and has an

Transmitter power control

operating range of 0.25 V to 1.4 V. The associated circuit determines the slope and intercept of the linear-in-d B GENERAL DESCRIPTION measurement system; these are nominally 23.6 m V/d B and −59.7 d Bm at 0.9 GHz. Further simplifying the application of

The AD8311 is a complete low cost subsystem for the precise

the AD8311, the input resistance of the setpoint interface is over

control of RF power amplifiers operating in the frequency range

35 MΩ, and the bias current is typically 0.26 µA.

0.1 GHz to 2.5 GHz and over a typical dynamic range of 50 d B. It is intended for use in cellular handsets and other battery- The AD8311 is available in a 6-ball wafer-level chip scale operated wireless devices. The log amp technique provides a package (WLCSP), 1.0 mm × 1.5 mm, and consumes 7.6 m A much wider measurement range and better accuracy than www.BDTIC.com/ADI from a 2.7 V to 5.5 V supply. controllers using diode detectors. In particular, its temperature stability is excellent over a specified range of −40°C to +85°C.

FUNCTIONAL BLOCK DIAGRAM

LOW NOISE

LOW NOISE

VPOS BAND GAP

GAIN BIAS

REFERENCE

1.35 HI-Z

DETDETDETDETDET

LOW NOISE RAIL-TO-RAIL BUFFER

OFFSET INTERCEPT

250m V TO

COMPENSATION POSITIONING

Figure 1.

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