A 2.7 50MHz IF-sampling DS-modulator with +37dBV IIP3for digital cellular phones

The design and experimental results of a 2.7V 50MHz switched-capacitor ΔΣ-modulator with a 2nd -order loop filter are presented. The circuit is targeted for the IF-section of a radio receiver in a digital cellular phone. It combines frequency downconversion with analog to digital conversion by directly sampling an input signal from an intermediate frequency of 50MHz. The measured peak SNR for a 100kHz signal band is 81dB with a 53MHz blocking signal. The dynamic range is 88dB and the measured IIP
3
with 50.38MHz and 50.8MHz interferers is +36.9dBV.