Versatility, Bandwidth and Efficiency: Digital GaN-Based Switch-Mode Supply Modulators

In this paper the versatility of ultra-fast and, at the same time, high-power capable digital electronics is demonstrated. An electronic switch based on 0.25μm GaN HEMT technology, originally designed as a digital microwave power amplifier, is reconfigured for different applications with the goal of extending the modulation bandwidth and efficiency of envelope tracking concepts. When configured as a DC/DC converter for continuous supply modulation a modulation bandwidth of 300 MHz is demonstrated using a clock frequency of 9.4 GHz for the low-pass delta sigma modulator. When configured as a class-G discrete supply modulator, excellent rise and fall times below 112 ps (10 % to 90 %) are achieved. This allows minimum pulse widths below 1 ns and IQ modulation bandwidth in the GHz range.