C products have begun to emerge. The ADCs/DACs that can directly sample the RF signal at gigahertz frequencies without the interleaving arti- facts provide new solutions to systems for direct RF digitization of communications systems, instrumentation, radar applications, etc. The earlier solutions required multiple stages of filter- ing, synthesizers, and mixers to translate the input signal to a reference frequency that then could be digitized by an ADC at about 100-Msamples/s conversion rate. However, now direct RF sampling is achievable with state-of-the-art wideband ADC technology. It must be noted that the speed while important is not the only performance factor to consider in the designs as the dynamic range and spectral noise level are other important considerations. In the past, the only monolithic ADC architectures that could run at GSPS speeds were flash converters with 6 or 8 bits of resolution. They were consuming excessive power and typically could not provide an effective number of bits (ENOB) beyond 7 bits due to the geometric size and power-constraint tradeoffs of flash architectures. The ENOB provides a measure of the performance of the ADC that is expressed in bits. ENOB is most accu- rately measured using a sine wave, curve-fitting method. The most common method for computing ENOB is to use the following equation based on the signal-to-noise-plus-dis- tortion (SINAD)9 at the full scale of the converter ENOB = (SINAD - 1.76)/6.02. The SINAD is the ratio of the rms signal amplitude to the rms value of the sum of all spectral components, including harmonics but excluding DC. The difference between SNR and SINAD is the energy contained in the first six harmonics. UE can perform UE cannot perform UE can perform UE cannot perform UE can perform transmission/ transmission/ transmission/ transmission/ transmission/ reception reception reception reception reception Utilized RF circuitry (serving cell) Unutilized RF circuitry (no serving cell) Subframe (1 ms) RF ON RF OFF Duration for attempting to detec