An implementation strategy for high-power, high resolution, fully digital transmitters (DTX) is proposed. It is based on a high-speed CMOS controller featuring a high-density flip-chip interconnect to an LDMOS power MMIC containing large arrays of custom low-VT LDMOS gate segments configured in RF-power switch banks. Using a two-level thermometer approach and a novel symmetric control scheme for the activation of the gate segments, a high-resolution 11-bit DTX switch bank is realized. It can provide peak RF powers >10 W at 45/40% peak drain/system efficiency at 3.525 GHz.@en

This work describes a fully digital transmitter (DTX) for 5G mMIMO base stations that combines the strengths of high-speed digital CMOS with the high-power capabilities of a Monolithic Microwave Integrated Circuit (MMIC) high-voltage technology. This technology platform offers high integration and scalability for implementing Radio Frequency Digital-to-Analog Converters (RF-DACs). To facilitate the digital operation of the gate-segmented output power stage, a custom VT-shifted LDMOS technology has been utilized. The relatively high output capacitance of the LDMOS devices makes digital class-C operation the preferred class of operation to achieve high efficiency with good linearity metrics for the digital power amplifier (DPA). In this work, we analyze this operation, assuming a trapezoidal-shaped current profile, which allows investigation of the impact of the non-zero rise and fall times on the theoretical (normalized) output power and drain efficiency.
To drive the gate segments in this custom VT LDMOS technology with a gate-to-source voltage (VGS) swing of 2.2 V, a driver is proposed comprising: inverter chains, a level shifter, and a high-voltage output buffer. This driver is fully digital and can be implemented using thin-oxide bulk CMOS devices whose VDD is limited to 1.1 V. A model of the DTX comprising only the drivers and DPA at the circuit level is created in ADS to evaluate the output power, drain efficiency, and system efficiency. The DTX is simulated at 3.5 GHz full power and achieves an output power of 19.79 W/23.43 W, a drain efficiency of 67.28%/59.22%, and a system efficiency of 60.34%/54.48% with a non-empirical and empirical model of LDMOS, respectively. Rise and fall times of around 20% of the RF cycle (tr = tf = 0.2/fc) are found to be the most suitable in terms of power consumption and system efficiency.

In the context of the Bachelor Graduation Project at the Delft University of Technology Department of Electrical Engineering, we have been tasked with a project to design prototype of a bi-static radar. This thesis describes the waveform design of a bi-static radar system and its implementation with Software Design Radio, SDR for short. The radar system can be mounted on delivery drones and used to detect other drones and obstacles to avoid collisions. The thesis focuses mainly on the radar waveform design. In addition, the thesis provides analysis of the radar system performance and system implementation with commercial off the shelf SDR. A proof of concept has been realised by means of simulations using the open source software GNU Radio Companion.