al domain. A new class of direct RF-sampling ADCs is being designed in advanced complementary metal-oxide semiconductor (CMOS) processes that allows much higher conversion rates with lower power relative to the previous generations. Furthermore, this approach enables higher integration, which is used for a low-power, multi-giga-bit serial interface, and on- chip DDC, leading to very size- and power-efficient digital interconnect between the data converter and digital processor. As shown in Fig. 5.24, in a super-heterodyne receiver, the input signal, which resides at an RF frequency, is down-converted to a lower IF frequency. It is then digitized prior to digital filtering and demodulation. Depending on the application, the input signal can range from 700 MHz to several GHz, while IF typically ranges from zero to 500 MHz. The classic super-heterodyne receiver consists of bandpass filters (BPFs), a LNA, mixer and LO, an IF amplifier, and ADC AAF [15,17]. In a direct-conversion receiver, the RF-sampling ADC replaces the signal chain from the mixer, which greatly simplifies the overall receiver design. The first RF BPF is typically a NF/sensitivity SFDR with blocker Antenna Bandpass Bandpass IF amp AAF/BPF filter filter Mixer Front-end Figure 5.24 Performance comparison between super-heterodyne and direct RF-sampling receivers [15]. Aperture jitter or aperture uncertainty is the sample-to-sample variation in aperture delay that can be mani- fested as frequency-dependent noise on the ADC input. Aperture delay is a measure of the difference in the delay between the analog path and the encode path. It is measured by observing the time from the 50% point of the rising edge of the sample clock to the time at which the input signal is actually sampled. New Radio Access RF and Transceiver Design Considerations 715 wideband, preselect filter, which provides most of the OOB rejection. It prevents signals that are far from the actual passband from saturating the analog front-end (AFE). The LNA increases the amplitude of weak s