Chip Design Of A High Spectral Efficiency Modulation

With the development of communication technology and the continuously improvement of the information transmission rate requirements in all fields of study, as an important non-renewable resources, wireless spectrum gradually exhibits its finiteness and scarcity. In the field of communications engineering, how to improve the spectral efficiency more effective has become a topic of concern.As one of the Ultra Narrow Band (UNB) modulation, Extended Binary Phase Shift Keying (EBPSK) can greatly improve the spectral efficiency by compressing signal bandwidth. It exhibits great potential.In this paper, TSMC 0.18μm CMOS technology is used to implement the EBPSK modulator, the modulator can work over the carrier frequency between 200MHz to 2.4GHz. This system consists of five parts:balun, mode selection circuit, control module, phase shift keying module and output buffer. The modulator implements three modulation:phase reversal modulation, Missing Cycle Modulation (MCM) and narrow pulse modulation, these modes are selectable. Using active structure to implement balun circuit to avoid the use of inductors, it effectively reduces the circuit area and the tape cost. Using double-balanced structure to implement the phase shift keying module in order to reduce the effects of clock feedthrough and charge injection. Since the baseband signal is not filtered, the modulated signal contains lots of high frequency components, we use shunt-peaking technology in output buffer to improve its bandwidth to improve the signal fidelity.The rusults of post-simulation show that the circuit meets the requirements when the carrier frequency from 200MHz to 2.5GHz. On-wafer test and bonding test are used in this paper, measurement results show that the circuit achieves the three modes and the three modes are selectable by controlling external signals. Power consumption of this chip is less than 60mW and the chip area is 0.70x0.68 mm2.