A GSM/EDGE/WCDMA modulator with on-chip D/A converter for base stations

Abstract

A global system for mobile communication (GSM)/enhanced data rates for GSM evolution (EDGE)/wideband code division multiple access (WCDMA) modulator with a 14-bit on-chip digital-to-analog (D/A) converter is presented. The modulator consists of several digital signal processing building blocks, including a programmable pulse shaping filter, interpolation filters, resampler, co-ordinate rotation digital computer (CORDIC) rotator, programmable output power level controller and ramping unit, and x/sinx filter. The precompensation filter, which compensates the sinc droop above the Nyquist frequency, makes it possible to use WCDMA signal images for up-conversion. The new programmable up/down unit allows power ramping on a time-slot basis as specified for GSM, EDGE and time division duplex (TDD)-WCDMA. The multistandard modulator meets the spectral, phase and error vector magnitude (EVM) specifications. The die area of the chip is 22.09 mm/sup 2/ in 0.35-/spl mu/m CMOS technology. Power consumption is 1.7 W at 3.3 V with 110 MHz.