CN103293390A - Test circuit for series inductance in MOSFET (metal oxide semiconductor field-effect transistor) power devices - Google Patents

Abstract

The invention discloses a test circuit for series inductance in MOSFET (metal oxide semiconductor field-effect transistor) power devices and belongs to the technical field of semiconductor device testing. The test circuit comprises a pulse generator, a phase display, an LCR meter, a resistor and a gating switch. The signal end of the pulse generator is electrically connected with a gate. The ground end of the pulse generator is electrically connected with the fixed end of the gating switch through a series resistor. Two selection ends of the gating switch are electrically connected with a source and a drain respectively. The ground end of the pulse generator is grounded. One end of the LCR meter is electrically connected with the gate, and the other end of the LCR meter is electrically connected with the fixed end of the gating switch. The current input end of the phase display is electrically connected with the gate, and the voltage input end of the phase display is electrically connected with the fixed end of the gating switch. The test circuit is applicable to providing important parameter indexes for estimating the performances of devices, and is significant to optimizing the design of MOSFET power devices and improving the switching characteristics of the devices.

Description

A kind of test circuit of power MOSFET device series inductance

Technical field

The present invention relates to the semiconducter device testing technical field, particularly a kind of test circuit of power MOSFET device series inductance.

Background technology

Power MOSFET device has in field of switches with superior performances such as its high frequency, low driving power, easy parallel connections to be used widely, and wherein the parasitic component of device inside can influence the switching characteristic of device.Fig. 1 is power MOSFET device switch equivalent model synoptic diagram in the prior art, has comprised the important parasitic component that influences the devices switch performance in the model.Wherein, source series inductance L _SWith drain electrode series inductance L _DIt is the important parameter that determines the device switching speed, their size directly influences the switch performance of device, mainly show: the existence of source series inductance can influence discharging and recharging the time of device input capacitance, especially device trunon delay time and turn-off delay time; The negative feedback meeting that the source series inductance produces causes grid current and drain electrode di/dt to set up mobile equilibrium, causes the devices switch capability error; The drain electrode series inductance not only can make drain-source voltage produce overshoot, also can increase turn-off power loss.Because the source electrode of power MOSFET device and drain electrode series inductance value are smaller, add the influence of device stray capacitance, thus can't use the LCR table directly to measure, thus can't accurately obtain the source series inductance L of power MOSFET device _SWith drain electrode series inductance L _D

Summary of the invention

In order to solve the problem that prior art can't directly accurately measure the power MOSFET device series inductance, the invention provides a kind of test circuit of power MOSFET device series inductance, its test philosophy is: the RLC series circuit and the RLC series circuit resonance principle that become the branch formation according to the power MOSFET device endoparasitism, apply a sine pulse at device grids, regulate sine pulse frequency size, seek the tuning-points of circuit simultaneously by the current phase in measure R lc circuit both end voltage and the circuit; When circuit reaches resonance, according to the resonance frequency of this moment and the capacitance that adopts the LCR table to measure, can calculate the inductance value in the circuit; Calculate the series inductance of power MOSFET device source electrode and drain electrode respectively by the control gating switch.Test circuit comprises pulse producer, phase place display, LCR table, resistance and gating switch; The signal end of described pulse producer is electrically connected with grid; The earth terminal of described pulse producer is electrically connected with the stiff end of gating switch by resistance in series; Two selecting sides of described gating switch are electrically connected with source electrode and drain electrode respectively; The earth terminal ground connection of described pulse producer; One end of described LCR table is electrically connected with grid, and the other end is electrically connected with the stiff end of gating switch; The current input terminal of described phase place display is electrically connected with grid, and voltage input end is electrically connected with the stiff end of gating switch.

Described pulse producer is the sinusoidal wave pulse generator.

Described phase place display is oscillograph.

The test circuit of power MOSFET device series inductance provided by the invention, by the gating switch series inductance value of measured power MOSFET device source electrode and drain electrode scientifically and rationally, overcome the problem that prior art can't directly accurately measure the power MOSFET device series inductance, so not only can provide the important parameter index for the performance of evaluator spare, and all be significant for the switching characteristic of optimizing power MOSFET device design, raising device.

Description of drawings

Fig. 1 is prior art power MOSFET device switch equivalent model synoptic diagram;

Fig. 2 is prior art RLC series resonant circuit figure;

Fig. 3 is the test circuit schematic diagram of embodiment of the invention power MOSFET device series inductance.

Embodiment

Below in conjunction with drawings and Examples, technical solution of the present invention is further described.

Fig. 2 is RLC series resonant circuit figure in the prior art.Series resonance refers to that the series circuit voltage and current of studying partly reaches same-phase, i.e. the capacitive reactance numerically equal of the induction reactance of inductance and electric capacity in the circuit, thus make the circuit of studying present the pure resistance characteristic.Corresponding frequency is resonance frequency f during resonance _r, its expression formula is:

$f_r=f\sqrt{\frac{X_C}{X_L}}=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}---\left(1\right)$

In the following formula, X _CAnd X _LBe respectively the capacitive reactance of electric capacity in the series resonant circuit and the induction reactance of inductance.When RLC series resonant circuit desire produces resonance, can adjust power pulse frequency f, inductance L or capacitor C, make its frequency reach resonance frequency f _r, and irrelevant with resistance.

The embodiment of the invention is utilized power MOSFET device switch equivalent model, in conjunction with RLC series resonant circuit principle, provides a kind of test circuit of power MOSFET device series inductance, as shown in Figure 3.This circuit comprises sinusoidal wave pulse generator, oscillograph, LCR table, resistance R ₀(R ₀For measuring the sample resistance that electric current is used) and gating switch S.Wherein, the signal end of sinusoidal wave pulse generator is electrically connected with grid; The earth terminal of sinusoidal wave pulse generator is by resistance in series R ₀Be electrically connected with the stiff end of gating switch S; Two selecting sides of gating switch S are electrically connected with source electrode and drain electrode respectively; The earth terminal ground connection of sinusoidal wave pulse generator; One end of LCR table is electrically connected with grid, and the other end is electrically connected with the stiff end of gating switch; Oscillographic current input terminal is electrically connected with grid, and voltage input end is electrically connected with the stiff end of gating switch.In actual applications, the sinusoidal wave pulse generator can be selected Tektronix AFG2021-SC for use, and oscillograph can be selected Tektronix MSO2014B for use, and the LCR table can be selected Agilent4285A for use.

Below in conjunction with test circuit shown in Figure 3, at length set forth the test process of power MOSFET device series inductance, specific as follows:

After installing measured power MOSFET device (DUT), earlier gating switch S is transferred to 1 position, this moment, grid and source electrode two ends constituted the RLC series resonant circuit; Utilize the sinusoidal wave pulse generator that two ends, device grid source are applied sine pulse, with current phase (Y2 end) in oscillograph monitoring rlc circuit both end voltage phase place (Y1 end) and the circuit, the frequency f of regulating sine pulse ₁Identical with current phase until voltage-phase, namely circuit reaches resonance (f ₁=f _r); At this moment, adopt LCR to show to test the capacitance C at two ends, grid source ₁, again according to formula (1), namely

Calculate source series inductance value L _S, namely

Again gating switch S is transferred to 2 positions, find resonance frequency f as stated above ₂=fr, and the capacitance C at test grid leak two ends ₂, again according to formula (1), namely

Calculate drain electrode series inductance value L _D, namely $L_D=\frac{1}{{4\mathrm{\&pi;}}^2{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HDA00003300252000021.png"\; state="\{\{state\}\}">f</figure-callout>}}_2^2{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00003300252000021.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}.$

The test circuit of the power MOSFET device series inductance that the embodiment of the invention provides, by the gating switch series inductance value of measured power MOSFET device source electrode and drain electrode scientifically and rationally, overcome the problem that prior art can't directly accurately measure the power MOSFET device series inductance, so not only can provide the important parameter index for the performance of evaluator spare, and all be significant for the switching characteristic of optimizing power MOSFET device design, raising device.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. the test circuit of a power MOSFET device series inductance is characterized in that, comprises pulse producer, phase place display, LCR table, resistance and gating switch; The signal end of described pulse producer is electrically connected with grid; The earth terminal of described pulse producer is electrically connected with the stiff end of gating switch by resistance in series; Two selecting sides of described gating switch are electrically connected with source electrode and drain electrode respectively; The earth terminal ground connection of described pulse producer; One end of described LCR table is electrically connected with grid, and the other end is electrically connected with the stiff end of gating switch; Described phase place display currents input end is electrically connected with grid, and voltage input end is electrically connected with the stiff end of gating switch.

2. the test circuit of power MOSFET device series inductance as claimed in claim 1 is characterized in that, described pulse producer is the sinusoidal wave pulse generator.

3. the test circuit of power MOSFET device series inductance as claimed in claim 1 is characterized in that, described phase place display is oscillograph.

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