A Monolithically Integrated GaN Comparator with Depletion-Mode Input for Power Converter Applications

The comparator is a vital block in any integrated DC-DC power converter for both control and protection functions. Monolithic GaN HEMT power converters offer superior power switching performance with lower on-resistances and capacitances, however they suffer from poor analog performance due to their lack of complementary devices and poor device mismatch as well as a limited range of devices. This paper presents the design of a depletion-mode input pair based regenerative comparator monolithically integrated on a GaN-on-Si process. This paper aims to investigate and demonstrate the input-referred offset performance of such a comparator. The structure delivers a transistor level simulated 1-σ input-referred offset of 3.6 mV without the use of any offset cancellation techniques. It achieves rising and falling propagation delays of 29 ns and 22 ns, respectively with a 100 mV overdrive and 1 pF load capacitance. The comparator occupies an area of approximately 0.055 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and has a quiescent current consumption of 63 μA.