Gate resistor

MOSFET (Ql). R4 is a gate resistor used to limit the current in the gate and to avoid any self-oscillations of the MOSFET because of noise. Components R7 and Cl provide compensation for the control loop. 

Further, since the charging and discharging paths of these capacitors often include the gate resistor, the value of the gate resistance also considerably impacts the transition time, and thereby the switching loss. 

Semiconductor control modules gate the thyristors, which switch cm rent to the motor field at the optimum motor speed and precise phase angle. This assures synchronizing with minimum system disturbance. On pull-out, the discharge resistor is reapplied and excitation is removed k> provide protection to the rotor winding, shaft, and external electrical system. The control resynchronizes the motor after the cause of pull-out i.n removed, if sufficient torque is available. The field is automatically applied if the motor synchronizes on reluctance torque. The control is calibrated at the factory and no field adjustment is required. The opti-... 

Gate electrodes in MOS devices for high value resistors to insure good ohmic contact to crystalline... 

In DC-DC converters, we can somewhat slow the turn-on of Fets if we insert a small resistor (10 to 20Q. typically) in series with the decoupling capacitor of their respective driver stages. For example, a small resistor can be placed in series with the bootstrap capacitor of the third-generation switcher family I used to cover. That helped with almost 10 to 20% of customers, but somehow this trick didn t find its way into the applications information section of their datasheet. If the Fets are external, we can try a small resistor in series with the Gate, but this affects both the turn-on and turnoff (with such low threshold voltages, a diode in parallel to the resistor will not do anything). 

So, if you can access the gates of the Fets, try putting in small resistors in series with them. If it is a switcher IC (with no access to the gates), try inserting a small resistor in series with the decoupling capacitor of the driver supply (usually a 0.1 pF capacitor attached to the Vdd pin and/or the bootstrap pin). Better still, pick an IC with less aggressive drive to start with. Because otherwise it will commit suicide sooner or later. 

The voltage at the anode of diode D6 in Fig. 10.29 was compared to the gate voltage waveform, shown below in Fig. 10.30a. The voltage (a representation of the switch current) across the sense resistor R2 was... 

The detection of the fluorescence is accomplished by a 1P21 photomultiplier tube pulsed to 1.5 kV for 2.5 /nsec. Small dynode resistors (50 Q) are employed to minimize the RC time of the tube. This results in a nearly rectangular gating. A 3E29-beam-power tetrode with both sections in parallel is operated as a hard-tube amplifier to provide the 1.5-kV pulse for... 

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