Advanced Delta-Sigma Transmitter Architectures for High Performance Wireless Applications
Abstract
To satisfy the wireless market’s growing demand for higher data rates services and to maximize the bandwidth spectral efficiency, modern modulation schemes have been developed. Transmitting spectrally efficient non-constant envelope signals modulated by modern schemes necessitates designing highly linear and efficient transmitter systems for reaching the signal-to-noise ratio (SNDR) requirements and longer battery life. Delta-sigma modulator (DSM) based transmitters have the potential of good linearity performance and re-configurability for multi-standard applications. They also enable the use of high efficiency switching power amplifiers (PAs). This thesis was dedicated to enhancing the performance of DSM based transmitters. The first part of the thesis will focus on the design and evaluation of a novel high-pass (HP) DSM- based digital-IF transmitter architecture to address the in-band quantization noise problem and low coding efficiency in Cartesian HP and band-pass (BP) counterparts.
As the most power consuming part of the transmitters, the design of highly efficient RF PAs has been the subject of several studies with different techniques being proposed to overcome this challenge. Dynamic control of the load impedance of the amplifier is a promising technique used in pulsed load modulation (PLM) PAs. Digital load modulation is realized in PLM PAs with the aid of the envelope delta-sigma modulator (EDSM) to enhance the efficiency in larger power back-off region while preserving the quality of the signal. The design and fabrication of a PLM PA with gate bias modulation for high power applications is the subject of the second part of this thesis. Employing the designed PLM PA, a digital DSM-based transmitter topology was realised for base-band applications. The transmitter was successfully tested with standard signals showing promising results. In the next step, it is shown that to further increase the efficiency of the PLM PA-based transmitters, it is possible to reduce the delta-sigma quantization noise and thus, the quality of the encoded signal by replacing the EDSM by a complex delta sigma modulator (CDSM). Based on this method, a novel transmitter architecture is proposed which benefits from CDSMs and PLM PAs for reaching the SNDR requirements and high efficiency performance at the same time.
Description
Keywords
Engineering--Electronics and Electrical
Citation
Jouzdani, M. (2017). Advanced Delta-Sigma Transmitter Architectures for High Performance Wireless Applications (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/24719