An Arbitrary Waveform Generator based on an Eight-Level Flying-Capacitor Multilevel Converter

Arbitrary waveform generators (AWG) are essential in various industrial and medical applications. These are typically large-signal amplitude and high frequency waveform generators, which require switching power converters in order to meet stringent transient performance requirements with high bandwidth and high efficiency. This paper presents an AWG design using an eight-level flying-capacitor multilevel (FCML) converter. The power stage design and a voltage controller are designed to achieve fast responses reference waveform transients, and an active control scheme based on duty cycle compensation is used to ensure that the flying capacitor voltages remain balanced under steady-state and transient conditions. The approach is verified on a 500 W eight-level digitally controlled GaN-based FCML prototype operating at a switching frequency of 400 kHz from 200 V input voltage, with output voltage varying from 25 V to 180 V, and with maximum output current of 2 A. Experimental results show that the prototype is capable of tracking various reference waveshapes including step, ramp, and sinusoidal, while at the same time regulating the flying capacitor voltages. For step transients between 25 V and 180 V the rise and the fall times are shorter than 3 µs.