A monolithic stacked Class-D approach for high voltage DC-AC conversion in standard CMOS

A fully-integrated Class-D DC-AC converter is realized in a 130 nm 1.2V CMOS technology with an on-chip inductor and capacitor. Several dies are combined to achieve higher output power. A multilevel topology allows the combined Class-D DC-AC system to achieve higher output voltages at a multiple of the nominal supply voltage of 1.2V. Problems such as hot carrier degradation and oxide breakdown are absent, since each subblock operates within the standard voltage limits. An off-chip low frequency signal can be used as a reference clock for the Class-D DC-AC converter using an on-chip PWM generation circuit. For this monolithic multilevel system, no discrete components are needed anymore, reducing the bill of materials. A maximum efficiency of 66.5% for a stand-alone die is reached. An output peak voltage of 2.4V peak-to-peak is achieved at an efficiency of 33% by using a combination of several dies. A total output power of 95mW is obtained.