High-Efficiency E-band Power Amplifiers and Transmitter in 55nm BiCMOS

This thesis presents the development of a new kind of power amplifiers and the design of a full E-band Transmitter designed in the analog integrated circuit laboratory of the University of Pavia. The mobile network structure is going to change drastically in the next years to handle the escalating needs for new standards and applications. Consequently, also the backhaul, i.e. the links connecting base stations to the central network, will undergo several modifications to allow higher performances in terms of speed and number of users and good quality of service. The power amplifiers presented in this work have been designed specifically to satisfy the requirements of the future backhaul transceivers, overcoming many challenging aspects of power amplifiers design at mm-Wave (30-300 GHz). The power amplifier is the most power hungry block of E-band transmitters for backhauling. Especially, an idea for improving the power efficiency with emphasis in back-off region (i.e. when the power amplifier delivers output power lower than the peak value) has been proposed. The idea exploits a common-base transistor in the output stage, where the BE junction performs current-clamping to adjust the average (DC) current according to the actual output power. Two prototypes have been realized in 55nm SiGe-BiCMOS technologies, demonstrating performances beyond the state-of-the-art. In the single-path PA, Psat is 19dBm while OP1dB is 18dBm. The measured PAE peaks to 23% while at OP1dB and 6dB back-off it is 22% and 8.5%, respectively. The measured Psat and OP1dB for dual-path PA are 21.5dBm and 20.5dBm, 2.5dB higher than for the single-path PA. The maximum PAE is 22% while PAE at OP1dB and 6dB back-off is 20% and 7.2%, respectively. As second major contribution, a direct conversion E-band transmitter focusing on signal path including up-conversion mixers and PAs has been designed and realized in 55nm SiGe-BiCMOS technology. Optimizations are performed from architecture level down to transistor level to minimize the power consumption while delivering high linear output power. The measured OP1dB and maximum output power for the realized E-band transmitter are 20.3dBm and 22dBm, respectively. The image rejection ratio of transmitter without baseband calibration is 40dBc (above 50dBc with baseband calibration) while the bandwidth is in the frequency range of 66-88GHz.