JPH05203697A - Method for measuring and extracting junction capacitance of transistor - Google Patents

Abstract

PURPOSE:To evaluate junction capacitance in a high frequency area and to automate, simplify and facilitate a system for measuring and extracting transistor model parameters by extracting the junction capacitance parameters of a transistor from data on the measurements of an S-parameter. CONSTITUTION:The base terminal B and collector terminal C of a transistor 9 to be tested are connected to the respective ports P1, P2 of an S-parameter measuring instrument through respective transistors 13. Because a base.emitter junction BE and a base-collector junction BC are evaluated in a reversely biased state, VCE=0V and VBE<0V and the bias dependencies of the base.emitter junction BE, the base-collector junction BC and the collector.substrate junction CS are measured while the values of two voltage sources 16, 17 are varied. After a bias voltage has been set, an S-parameter is measured by the S- parameter measuring instrument and the S-parameter measured is converted into a Z-parameter and the true portion of the Z-parameter is set to zero and is converted into a Y-parameter so as to obtain the capacitance of each junction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring and extracting each junction capacitance of a transistor that can be simplified and automated when performing circuit simulation or the like.

[0002]

2. Description of the Related Art Measurement of transistor model parameters is essential for circuit simulation. Of these, the measurement and extraction of the junction capacitance parameter is necessary for expressing the AC characteristics and transient characteristics of the transistor. The capacitance bridge method has been conventionally used for measuring and extracting the junction capacitance parameter.

FIG. 9 shows a circuit diagram of the principle of measuring the junction capacitance by a simple capacitance bridge method which has been used conventionally.
In the figure, 1 is a diode to be measured, 2 and 3 are variable resistors, 4
Is a standard capacity, 5 is an AC ammeter, 6 is an AC signal source, 7 is a choke coil for bias supply, and 8 is a power supply for bias.

The method of obtaining the junction capacitance Cj of the diode 1 to be measured by the bridge circuit shown in FIG. 9 will be described below. The two variable resistors 2 and 3 are adjusted so that the measured value of the AC ammeter 5 becomes zero. From the resistance values P and Q of the variable resistors 2 and 3 and the value Cs of the standard capacitance 4 at that time, respectively. , Diode to be measured 1
The junction capacitance Cj of is calculated by the following equation.

[0005]

[Equation 1] Further, the bias dependency of the junction capacitance Cj of the diode 1 under measurement, which is necessary for parameter extraction, can be obtained by changing the voltage of the bias power supply 8 and repeating the measurement.

FIG. 10 shows the principle of a conventional transistor parameter measurement / extraction system. In the figure, 9 is a transistor to be measured, 10 is a capacitance / voltage characteristic measuring device,
11 is an S-parameter measuring device, 12 is a current / voltage characteristic measuring device, 13 is a bias transistor for supplying bias during S-parameter measurement, 14 is a controller for controlling a measuring instrument, 15 is a transistor under test 9 and each measuring device 10. , 11 and 12 connection changeover switches.

With the measurement and extraction system shown in FIG.
The DC parameter expressing the static characteristics of the transistor is obtained from the measurement result of the current / voltage characteristic measuring device 12, and the junction capacitance parameter is obtained from the measurement result of the capacitance / voltage characteristic measuring device 10 using the capacitance bridge method. Parameters such as carrier travel time are calculated from the measurement results of the frequency characteristics of the S parameters by the S parameter measuring device 11. Here, in order to perform measurement extraction of all these parameters smoothly and efficiently, 3
Measuring devices 10, 11, 12 and transistor under test 9
It is necessary to smoothly switch the connection.

[0008]

When the capacitance bridge method shown in FIG. 9 is applied to the measurement of the junction capacitance of a high frequency transistor, it is difficult to measure at a high frequency of 100 MHz or more,
There is a problem that the capacitance cannot be measured at the actual operating frequency. This is mainly because it is difficult to realize a high precision variable resistor having excellent high frequency characteristics.

Further, when the circuit by the capacitance bridge method shown in FIG. 9 is to be incorporated into a series of transistor parameter measurement / extraction systems, it is not easy to change the connection with a device for measuring other parameters, and a series of transistors is used.・
It makes automation of parameter measurement and extraction difficult.

Therefore, the measurement extraction system shown in FIG. 10 is used, but in the system shown in FIG.
The junction capacitance is measured with two terminals each between the base and the emitter and between the base and the collector, and is not easy because it is significantly different from the static characteristic measurement and the S parameter measurement by the three terminal connection. No, making automation difficult.

It should be noted that a simple automation method can be considered simply by using a matrix switch or the like as the switching unit 15, but in this case, the switch becomes complicated and a new switch circuit is required. There is a new problem that the insertion causes a measurement error.

In view of the above-mentioned problems of the prior art, the present invention provides an S-parameter for simplification and automation of a junction capacitance parameter measurement extraction and a transistor model parameter measurement extraction system at high frequencies. It is intended to provide a method of extracting a junction capacitance parameter of a transistor from the measurement data of.

[0013]

The problems of the prior art described above are solved by adopting the following novel characteristic construction method of the present invention. That is, the feature of the present invention is that the two-port S-parameter data of the transistor under measurement is first measured in the state where each junction forming the transistor under measurement is reverse biased, and then the data of the S-parameter is Z It is converted into parameter data, and then the real part of the resistance component of the Z parameter data is set to zero, and the Z parameter data having only the imaginary part of the capacitance component is converted into Y parameter data, and finally, This is a method for measuring and extracting the junction capacitance of a transistor by calculating each junction capacitance of the transistor under measurement from the Y parameter data.

[0014]

Since the present invention adopts the above-mentioned method,
The junction capacitance parameter of the transistor can be extracted from the S parameter measurement data, and the capacitance parameter of each transistor junction can be measured and extracted at the same time with the three terminals connected, and further evaluation in a high frequency region becomes possible. ..

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a procedure diagram showing a procedure for extracting a junction capacitance parameter of a transistor under measurement from S parameter measurement data of this embodiment, and FIG. 2 is a diagram for measuring an S parameter necessary for extracting the junction capacitance of a transistor under measurement. It is a circuit diagram which shows the structure of bias supply.

In the figure, 16 and 17 are voltage sources. In addition,
The same members as those in the conventional example are designated by the same reference numerals. A procedure for extracting the junction capacitance parameter of the transistor from the measurement data of the S parameter in this embodiment will be described with reference to FIGS. 1 and 2.

Setting of Bias Voltage Base terminal B and collector terminal C of transistor under test 9
Are connected to the respective ports P1 and P2 of the S-parameter measuring device 11 through the bias transistors 13, respectively. Further, the potentials of the base terminal B and the collector terminal C are the same as those of the voltage source 1.
6,17.

In FIG. 2, VCE = 0V and VBE <0V in order to evaluate the base-emitter junction and the base-collector junction in the reverse bias state. Between base B and emitter E of transistor under test 9, base B
The bias dependence between the collector C and between the collector C and the substrate S can be measured by changing the values of the two voltage sources 16 and 17 [step I].

Measurement of S Parameter After setting the bias voltage in step I, the S parameter is measured by the S parameter measuring device 11 such as a network analyzer. Since the measurement system for S-parameter measurement is generally as low as 50Ω, highly accurate measurement is possible even at a high frequency of several tens GHz or more [Step II].

Conversion to Z parameter In order to calculate the capacitance parameter with high accuracy, the measured S
Convert parameters to Z parameters [Step III
].

The real part of the Z parameter is set to zero. When each junction forming the transistor under test 9 is in a reverse bias state, the resistance of the junction is sufficiently high and can be ignored. Therefore, an equivalent circuit of the transistor 9 is as shown in FIG. Can be expressed as Here, 18, 19 and 20 are a base resistance rb, an emitter resistance re and a collector resistance rc inside the transistor 9, respectively, and 21, 22 and 23 are a base B-collector C capacitance Cbc and a base B inside the transistor 9 respectively.・ Capacitance between emitter E and Cbe between collector C and substrate S Cc
s. The Z parameter calculated from the equivalent circuit of FIG. 3 is as follows.

[0022]

[Equation 2]

[Equation 3]

The point to be noted in the above equations (2) and (3) is that the real part of each Z parameter becomes the resistance component and the imaginary part becomes the capacitance component, so that the resistance component and the capacitance component can be easily separated. This is possible. Since the resistance component becomes an error factor when calculating the capacitance, the real part is set to zero here [Step I
V].

Conversion to Y Parameter Here, the Z parameter with the real part being zero and the imaginary part only being Y
Converting to parameters,

[Equation 4] [Step V].

Calculation of each junction capacitance Therefore, as is clear from these equations, each junction capacitance is
It is possible to easily calculate independently as in the following equation.

[Equation 5]

By repeating the above steps by varying the bias voltage, the bias dependency of the junction capacitance can be evaluated [step VI]. 4 and 5 are graphs CBC and CBE as results of measuring and extracting the frequency characteristics of the base-collector and base-emitter junction capacitances of the transistor according to the present embodiment.

The five characteristics in the figure show characteristics at different junction bias voltages. It can be seen that measurement extraction at a high frequency of 10 GHz is possible. 6 and 7 are graphs B-C-TBC and B-C-TBE2, which are results of evaluating the junction bias dependence between the base B / collector C and between the base B / emitter E, respectively. The broken line shows the result obtained by the method of this embodiment, and the solid line shows the result obtained by the conventional method. Equivalent characteristics are obtained, and it can be seen that it can be sufficiently applied as an alternative to the conventional method.

FIG. 8 is a diagram showing a series of bipolar transistor model parameter measurement / extraction system when this embodiment is used. As compared with the conventional system of FIG. 10, the capacitance-voltage characteristic measuring device 10 and the connection switching unit 15 are not required, so that measurement and extraction of a series of model parameters can be simplified and automation can be easily performed. In the present embodiment, the bipolar transistor has been described as an example, but it is also applicable to measurement and extraction of the capacitance parameter of the field effect transistor or the like.

[0029]

As described above, according to the present invention, by applying the method of extracting the junction capacitance parameter of the transistor under measurement from the measurement data of the S parameter, it is possible to achieve the same as the extraction of other model parameters. Capacitance parameters of each transistor junction can be extracted and measured at the same time with three terminals connected, and evaluation in a high frequency region is possible, and further, a series of parameter measurement and extraction system can be simplified. Demonstrate excellent usefulness.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure for extracting a junction capacitance parameter of a transistor from S parameter measurement data according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of bias supply when measuring an S parameter necessary for extracting a junction capacitance.

FIG. 3 is a circuit diagram simply showing an equivalent circuit of a transistor when each junction forming the transistor is in a reverse bias state.

FIG. 4 is a transistor base according to an embodiment of the present invention;
It is a graph of the result of having measured and extracted the frequency characteristic of the junction capacitance between collectors.

FIG. 5 is a graph showing the results of measuring and extracting the frequency characteristics of the junction capacitance between the base and emitter of the transistor.

FIG. 6 is a graph of results of evaluation of junction bias dependence between a base and a collector according to an embodiment of the present invention.

FIG. 7 is a graph showing the results of evaluation of the junction bias dependence between the base and the emitter.

FIG. 8 is a block circuit diagram of a series of bipolar transistor model parameter measurement extraction systems using an embodiment of the present invention.

FIG. 9 is a principle diagram of a conventional junction capacitance measurement by a simple capacitance bridge method.

FIG. 10 is a block circuit diagram of a conventional transistor parameter measurement and extraction system.

[Explanation of symbols]

 1 ... Diode to be measured 2, 3 ... Variable resistor 4 ... Standard capacity 5 ... AC ammeter 6 ... AC signal source 7 ... Bias supply choke coil 8 ... Bias power supply 9 ... Transistor under test 10 ... Capacitance / voltage characteristic measurement Device 11 ... S-parameter measuring device 12 ... Current / voltage characteristic measuring device 13 ... Bias supply bias transistor 14 ... Various measuring device control controller 15 ... Connection changeover switch 16,17 ... Voltage source 18 ... Transistor internal base resistance 19 ... emitter resistance inside the transistor 20 ... collector resistance inside the transistor 21 ... base-collector capacitance of the transistor internal junction 22 ... base-emitter capacitance of the transistor internal junction 23 ... collector-substrate capacitance B of the transistor internal junction B ... base C ... Collector E ... Emitter S ... Substrate P1, P2 ... Port

Claims (1)

[Claims] 1. When the respective junctions forming a transistor under measurement are reverse biased, first, two-port S parameter data of the transistor under measurement is measured, and then the S parameter data is converted into Z parameter data. Then, the real part of the resistance component of the Z parameter data is set to zero, and the Z parameter data in which only the imaginary part of the capacitance component is converted to Y parameter data, and finally the Y parameter is converted. .Measurement and extraction method of transistor junction capacitance, which is characterized by calculating each junction capacitance of transistor under test from data