Text preview for : 5992-0207EN Precise Evaluation of Input_252COutput_252C and Reverse Transfer Capacitances of Power D part of Agilent 5992-0207EN Precise Evaluation of Input 252COutput 252C and Reverse Transfer Capacitances of Power D Agilent 5992-0207EN Precise Evaluation of Input_252COutput_252C and Reverse Transfer Capacitances of Power Devices - White Paper c20141010 [15].pdf
Back to : 5992-0207EN Precise Evalu | Home
Keysight Technologies
Precise Evaluation of Input, Output, and
Reverse Transfer Capacitances of Power Devices
White Paper
2 | Keysight | Precise Evaluation of Input, Output, and Reverse Transfer Capacitances of Power Devices - White Paper
Increasing Importance of Capacitance Measurement
The switching frequency in power conversion circuits is increasing. This is primarily to reduce
the size of passive components such as smoothing capacitors and reactors. Accurate char-
acterization of device parameters affecting switching performance become more important
as higher switching frequencies increase power circuit switching losses. Let's use the power
MOSFET shown in Figure 1 as an example.
Gate resistance (Rg), input, output and reverse transfer capacitances (Ciss, Coss and Crss) are
described in a device datasheet as typical parameters related to switching performance.
Figure 1. Three Capacitances of Power MOS FET
Rg and Crss dictate switching speed while Ciss determines driving condition. Power loss due
to charging and discharging Coss is the primary component of switching loss in the case of a
resonant converter. Crss and Coss have voltage dependency in the nano-farad range due to the
power device's depletion region modulating with applied varying operational voltages.
These capacitances are conventionally measured by LCR meter. However, the maximum volt-
age of an integrated LCR voltage source is limited to around