70-MHz IF 10-MHz bandwidth bandpass $$\Upsigma\Updelta$$ modulator for WCDMA applications.

A MASH bandpass $$\Upsigma\Updelta$$ modulator for wide-band code division multiple access (WCDMA) applications is presented. The signal bandwidth of the proposed modulator is 10 MHz centered around an intermediate frequency (IF) of 70.5 MHz. Two two-path second-order bandpass $$\Upsigma\Updelta$$ modulators make the MASH architecture, which realizes a noise transfer function with four couples of complex conjugate zeros. The proposed circuit, fabricated with a 0.18 μm CMOS technology, uses a sampling frequency of 180 MHz to obtain a resolution of about 12 bits in the 10 MHz bandwidth around the IF. The measured modulator power consumption is 95 mW with a supply voltage of 1.8 V. The achieved figure-of-merit ( FoM) is 0.37 pJ/conversion-level. [ABSTRACT FROM AUTHOR]