Design of multi-gigabit serial link transceiver using bandwidth-efficient half-symbol-rate-carrier offset quadrature phase shift keying modulation

My research introduces new quadrature phase-shift-keying (QPSK) modulation techniques for high-speed data communication systems that use two orthogonal half-symbol-rate-carrier (HSRC) signals by which channel bandwidth requirements are reduced compared to that of the conventional non-return-to-zero (NRZ) modulation. The proposed HSRC offset-QPSK (HSRC-OQPSK) improves spectral efficiency by reducing the side lobes of the signal spectrum. In addition, HSRC minimum-shift keying (HSRC-MSK) modulation is also introduced. The performances and the simulation results of the proposed modulation techniques are studied and compared with those of the conventional ones.; Using the proposed HSRC-OQPSK modulation, a prototype transmitter generating the HSRC-OQPSK signal was designed and built. Measurement results confirm the theory that the proposed HSRC-OQPSK modulation improves spectral efficiency by reducing the second lobe of the signal spectrum by 10dB. Furthermore, the HSRC-OQPSK modulation reduces the first null bandwidth by 25% compared to the standard Non-Return-to-Zero (NRZ) modulation. Like NRZ, HSRC-OQPSK uses a 2-level data decision which enables a simpler transceiver architecture than multi-level pulse amplitude modulations (PAM), such as 4-PAM and duobinary.; My research also examines a modified Costas loop for the clock and data recovery (CDR) involving HSRC-OQPSK modulation. Behavioral model simulation has verified analysis of the proposed CDR. The carrier frequency of the HSRC-OQPSK signal is quarter data rate. Hence the proposed CDR is comparable to quarter-rate CDR using quadrature-phase VCO (QVCO), which relaxes the timing constraints and allows a simple structure as well.; The HSRC-OQPSK transceivers are implemented and simulated with TSMC and UMC 0.18microm CMOS technology to prove the theoretical performance. The theory and the measurement results show that it is feasible to increase the data-rate in wire-line communications using low-cost channels.