Design and Implementation of the RF Transceiver for LTE User Equipment.

Abstract

Lately, in-phase/quadrature (I/Q) phase clock generation has been widely inspected and extensively used in modern wired, and wireless communication systems. Low-cost fully integrated wireless transceivers mostly use image-reject (low-IF) or direct conversion (zero-IF) topologies, both topologies need high accurate quadrature signals for I/Q modulation/demodulation for superior image rejection [55]. Quadrature phases can be generated using many techniques such as RC poly-phase filter [85, 86], the cascaded RC filter stages are wanted to produce good quadrature signals, and this attenuates the signal significantly and perhaps must be buffered from the preceding VCO. Another method is the ring oscillators [87, 88], the ring oscillator consumes less area than an LC VCO, but they have poor phase noise, and consume high power. So that the ring oscillators are disqualified in modern RF transceivers application. Also, frequency dividers, delay-locked loops, and quadrature voltage-controlled oscillators (QVCO), usually minimize the power consumption at the expense of silicon area. Conventional QVCO consists of two similar cross coupled LC oscillators, where the LC oscillators couple through passive elements, and it is called passive coupling [89, 90] or through active devices, called active