60-dB 70-V/μs Three-Stage Op-Amp With Dual Single-Miller Frequency Compensation in GaN-IC Technology

Abstract

Modern high-performance electronics is pushing Si technology to its limits. Gallium Nitride (GaN) emerges as a promising alternative due to its superior properties in high-frequency and high-power applications. To fully utilize the fast-switching ability of the GaN technology, monolithic integration is a key. A monolithically integrated GaN power IC (Integrated Circuit) reduces the inductive parasitic enabling a fast efficient switching operation. However, GaN basic building blocks, particularly operational amplifiers (Op-Amps), face severe challenges due to the limitations of the GaN technology. This paper presents the first three-stage Op-Amp for high-performance feedback circuits realized in the IMEC’s 200-V GaN-IC technology on a GaN-on-SOI (Silicon on Insulator) substrate. The design utilizes a cascade of three differential stages resistively loaded to achieve a nearly 60-dB DC gain and 25-MHz gain-bandwidth and implements a novel dual single-Miller frequency compensation technique to provide closed-loop stability. The Op-Amp offers a Slew Rate exceeding 70 V/μs with 1% settling time of about 120 ns at room temperature. The correct circuit functionality from −40 °C to 150 °C was demonstrated through simulations and experimental test.