Thispaper presents a monolithic CMOS implementation of an envelope elimination and restoration linearization system that improves the linearity of efficient RF power amplifiers. The linearization IC, which occupies 4.3 mm 2 when implemented in a 0.8-µm CMOS technology, consists of a limiter, envelope detectors, and a delta-modulated switching power supply. This circuit was used to linearize AMPS (Advanced Mobile Phone System) cellular power amplifiers transmitting NADC (North American Digital Cellular) wave-forms. Measurements show that the linearized outputs meet the spectral mask and phase distortion requirements of NADC. The linearization system can improve the overall efficiency from 36% to 49%, while increasing the maximum linear output power from 26.5dBm to 29.5dBm.

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A modeling technique for planar microstrip spiral inductors in the presence of lossy media, such as in CMOS and bipolar technologies, is presented. The new model for spiral inductors incorporates the frequency dependent substrate effects via analysis of the the 'skineffect' mode of the microstrip structure.

Abstred -Sir trends in WLAN systems are described. For each trend, implications for the WLAN RFlCs are described. The six trends include increasing levels of integration, dual band operation. large percentage tuning h g e s , ver). high data rates, long range capability, and PA dlicicncy cnhanrements. Potential solutions to these issues $re examined. I new extended range mode, Tx power control $).stem, and amplifier emciency enhaneement approach is presented. Regulatory and performance requirements are described. Radio architecture, RF circuit design techniques, and system solutions are all described. Several examples are drawn from a siagle-cbip, dual-band, CMOS transceiver for IEEE 802.11a/h/g sireless LAN designed at the author's company. Index Terms -Wireless LAN, power amplifiers, OFDII, 802.11, power control, hllMO, direet conversion. Fig. I. Comparison of direct conversion and two step predistortion, convex optimization. conversion radios.%-= syynth.

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