EMC and switching loss improvement for fast switching power stages by di/dt, dv/dt optimization with 10ns variable current source gate driver

There is a growing need for motor drives with improved EMC in various automotive and industrial applications. An often referenced approach to reduce EME is to change the shape of the switching signal to reduce the EMI caused by the voltage and current transitions. This requires very precise gate control of the power MOSFET to achive better switching behaviour and lower EME without a major increase in switching losses. In order to find an optimal trade-off, this work utilizes a monolithic current mode gate driver with a variable output current that can be changed within 10ns. With this driver, measurements with different gate current profiles were taken. The di/dt transition was confirmed to be as important as the dv/dt transition in the power MOSFET. As a result of the improved switching behavior the emissions were reduced by up to 20dB between 7MHz and 60MHz with a switching loss that is 52% lower than with a constantly low gate current

Gate driver with 10 / 15ns in-transition variable drive current and 60% reduced current dip

The power supply is one of the major challenges for applications like internet of things IoTs and smart home. The maintenance issue of batteries and the limited power level of energy harvesting is addressed by the integrated micro power supply presented in this paper. Connected to the 120/230 Vrms mains, which is one of the most reliable energy sources and anywhere indoor available, it provides a 3.3V DC output voltage. The micro power supply consists of a fully integrated ACDC and DCDC converter with one external low voltage SMD buffer capacitor. The micro power supply is fabricated in a low cost 0.35 μm 700 V CMOS technology and covers a die size of 7.7 mm². The use of only one external low voltage SMD capacitor, results in an extremely compact form factor. The ACDC is a direct coupled, full wave rectifier with a subsequent bipolar shunt regulator, which provides an output voltage around 17 V. The DCDC stage is a fully integrated 4:1 SC DCDC converter with an input voltage as high as 17 V and a peak efficiency of 45 %. The power supply achieves an overall output power of 3 mW, resulting in a power density of 390 μW/mm². This exceeds prior art by a factor of 11

10ns variable current gate driver with control loop for optimized gate current timing and level control for in-transition slope shaping

Modern power transistors are able to switch at very high transition speed, which can cause EMC violations and overshoot. This is addressed by a gate driver with variable gate current, which is able to control the transition speed. The key idea is that the gate driver can influence the di/dt and dv/dt transition separately and optimize whichever transition promises the highest improvement while keeping switching losses low. To account for changes in the load current, supply voltage, etc., a control loop is required in the driver to ensure optimized switching. In this paper, an efficient control scheme for an automotive gate driver with variable output current capability is presented. The effectiveness of the control loop is demonstrated for a MOSFET bridge consisting of OptiMOS-T2™devices with a total gate charge of 39nC. This bridge setup shows dv/dt transitions between 50 to 1000ns, depending on driving current. The driver is able to switch between gate current levels of 1 to 500mA in 10/15ns (rising/falling transition). With the implemented control loop the driver is measured to significantly reduce the ringing and thereby reduce device stress and electromagnetic emissions while keeping switching losses 52% lower than with a constant current driver