A novel CMOS integrated pulse-width modulation (PWM) control circuit allowing smooth transitions between conversion modes in full-bridge based bi-directional DC-DC converters operating at high switching frequencies is presented. The novel PWM control circuit is able to drive full-bridge based DC-DC converters performing step-down (i.e. buck) and step-up (i.e. boost) voltage conversion in both directions, thus allowing charging and discharging of the batteries in mobile systems. It provides smooth transitions between buck, buck-boost and boost modes. Additionally, the novel PWM control loop circuit uses a symmetrical triangular carrier, which overcomes the necessity of using an output phasing circuit previously required in PWM controllers based on sawtooth oscillators. The novel PWM control also enables to build bi-directional DC-DC converters operating at high switching frequencies (i.e. up to 10 MHz and above). Finally, the proposed PWM control circuit also allows the use of an average lossless inductor-current sensor for sensing the average load current even at very high switching frequencies. In this article, the proposed PWM control circuit is modelled and the integrated CMOS schematic is given. The corresponding theory is analysed and presented in detail. The circuit simulations realised in the Cadence Spectre software with a commercially available 0.18 mm mixed-signal CMOS technology from UMC are shown. The PWM control circuit was implemented in a monolithic integrated bi-directional CMOS DC-DC converter ASIC prototype. The fabricated prototype was tested experimentally and has shown performances in accordance with the theory.

Monolithically integrated RC-snubbers were realized by metal-insulator-semiconductor capacitors on a silicon substrate also serving as a series resistor. These devices provide a promising alternative to passive surface-mounted device components that are commonly used for snubber applications in power electronic circuits. The surface area of the substrate was enlarged with circular trench structures to increase the integration level of the capacitor, and a silicon nitride layer with a thickness of 1.05 μm was deposited on top of a 20 nm-thin silicon oxide layer as a potential dielectric for applications up to 600 V. With the trench geometry, a capacitance per surface area of 0.6 nF/mm2 was achieved, which is more than ten times the capacitance of a planar device using the same dielectric layers. However, combining the thick silicon nitride layer with the trench geometry caused an excessive wafer bow of nearly 800 μm, so deposition and structuring of a surface passivation layer, such as polyimide, was not feasible. Therefore, inert oil had to be used as a surface passivation for high voltage measurements. The silicon nitride dielectric exhibits a leakage current density lower than 0.3 nA/mm2 at the requested 600 V operating voltage, while dielectric breakdown of the devices is observed at 1050 V. A low deviation in capacitance and series resistance across the wafer and a high yield regarding the high voltage stability is achieved because of the good quality and homogeneity of the silicon nitride dielectric layer.

Matrix converters are said to be integrable in smaller installation areas rather than DC-link converters due to the absent DC-link capacitor. In return the matrix converter may require input filters larger in size compared to the DC-link converter to suppress the power grid perturbations with the objective of keeping the perturbations below the normative regulated limits. Henceforth, a fair handed comparison has to be performed for the input filters' installation spaces of both converters investigated on a common basis of comparison. As the the power grid perturbations of both systems have already been presented in a prior work as well as a generic filter calculation method, which fits both systems, in this paper the absolute values of the input filters are introduced for the full normative frequency range. Dilating the prior presented results, a method for varying the PWM frequency in a very calculation time saving way is presented for so-called pseudo-spectra, contain ing the maximum values of the amplitudes occuring under permutation of the spectra influencing parameters

The reliability of monolithic integrated 200 V RC-snubbers in silicon is investigated both on wafer and module level. The wafer level measurements indicate that the capacitor dielectric is capable of repetitively withstanding 200 V pulses with a continuous use voltage of 150 V for 46 years with a failure rate of 1 ppm. Potentially early failing devices can be identified on wafer level by a screening test. The RC-snubbers exhibit excellent stability to high temperature and high humidity high temperature based stress tests and to thermal cycling. This makes these devices a promising alternative to discrete surface mounted devices in RC snubber applications for modules in power electronic applications