You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: GaN Power Integration for High Frequency and High Efficiency Power Applications: A Review 
Chapter Title:  IV. GAN POWER INTEGRATION FOR SMART POWER CONVERSION ICS 
1. Abstract of Cited Paper (BIB001):  Due to its remarkably high Johnson figure of merit, gallium nitride (GaN) has become the material of choice for applications requiring high output power at high frequencies. In this paper, we have reviewed high-speed switching work to date and we demonstrate a 28 V, 865-MHz switching speed step-down converter that can be applied to envelope tracking (ET). We report a GaN monolithic microwave integrated circuit technology utilized to fabricate a gate driver IC at a switching speed >1 GHz with 100 V breakdown GaN power switch. The on-chip integration of the power switch and gate driver allows in-circuit characterization of the power switch switching speed. Using the integrated gate driver and switch, we report a slew rate of the power switch of 152 V/ns at 50 V, which enables a down converter IC capable of ET with over 50-MHz tracking bandwidth. This paper shows the first demonstration of a GaN low-side gate driver capable of >1-GHz switching, monolithic integration with a 0.15- $\mu \text{m}$ T-gate suitable for up to Ka-band operation, and a >100 V breakdown voltage power switch on the same chip. 
2. Abstract of Cited Paper (BIB002):  Integration is a key step in utilizing advances in GaN technologies and enabling efficient switched-mode power conversion at very high frequencies (VHF). This paper addresses design and implementation of monolithic GaN half-bridge power stages with integrated gate drivers optimized for pulsewidth-modulated (PWM) dc–dc converters operating at 100 MHz switching frequency. Three gate-driver circuit topologies are considered for integration with half-bridge power stages in a 0.15- $\mu$ m depletion-mode GaN-on-SiC process: an active pull-up driver, a bootstrapped driver, and a novel modified active pull-up driver. An analytical loss model is developed and used to optimize the monolithic GaN chips, which are then used to construct 20 V, 5 W, 100 MHz synchronous buck converter prototypes. With the bootstrapped and the modified pull-up gate-driver circuits, power stage efficiencies above 91% and total efficiencies close to 88% are demonstrated. The modified active pull-up driver, which offers 80% reduction in the driver area, is found to be the best-performing approach in the depletion-mode GaN process. These results demonstrate feasibility of high-efficiency VHF PWM dc–dc converters based on high levels of integration in GaN processes.

Literature Review:
The GaN power integration for smart power conversion ICs is expected to improve the efficiency of DC power converters by replacing the switching transistors and Schottky diodes with GaN devices. The above mentioned MMIC process can form GaN integrated converters operating at very high frequencies BIB002 , BIB003 , BIB001 . However, the Schottky gate of AlGaN/GaN HEMTs restricts the input voltage swing, and the gate leakage current could cause deterioration in analog function of integrated circuit components. The negative normally-ON threshold voltage and Schottky gate require extra matching network or off-chip Field-Programmable Gate Array (FPGA) to obtain negative control signal with proper swing. So the integration with normally-OFF MIS-HEMTs is a promising solution for high frequency and high efficiency power conversion application.