JP3350712B2 - Frequency multiplier element characteristic evaluation method and frequency multiplier element characteristic evaluation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for evaluating the frequency multiplication characteristics of devices such as transistors and diodes, and more particularly to a large signal design of a frequency multiplier for microwave and millimeter wave frequency bands. The present invention is characterized in that a mechanical tuner suitable for performing load pull measurement is used.

[0002]

2. Description of the Related Art A phase-locked oscillator (PLO) is considered as a promising candidate as a signal source of high stability and low phase noise required in an active high data rate Ka band wireless communication system. Instead of directly phase-locking the millimeter-wave oscillator, the method of multiplying the output of the microwave PLO by one or more stages of frequency multipliers is costly,
It is considered to be an effective approach in terms of power consumption and phase noise. The operating principle of the frequency multiplier is based on the non-linearity of the device, and its design has been performed in most cases on a microwave circuit simulator using a large signal operation device model. However, the accuracy of device modeling is often insufficient for class B operation, which is often used as an operating point of a frequency multiplier.

As an alternative to device modeling, a method is known in which a tuner is connected to the input / output terminals of the device, the impedance of the tuner is changed, and the load impedance at which the output power, gain, etc. are optimized is directly measured by load pull (signal source). This is known as source pull on the side, and has been mainly used for evaluating the performance of high-power devices and designing high-power amplifiers. A method using a mechanical tuner as a tuner is performed as a relatively simple load-pull measuring method, and in recent years, a highly accurate measurement can be performed in a short time using a commercially available automatic tuner.

FIG. 7 shows such a conventional load-pull measuring system.
Shown in The frequency-multiplier element characteristic evaluation apparatus 100 connects a mechanical tuner to each of the source-side measurement system 102 and the load-side measurement system 103 of the device under test 101 and mechanically changes the impedance thereof, thereby realizing actual input / output. Conditions for matching the signal level on the source side and the load side are obtained by measurement, and the output power, gain, and the like are optimized.

[0005] A mechanical tuner for coaxial connection that is currently in practical use is called a slug tuner, and its structure is shown in FIG. The line of the slag tuner 104 forms a parallel plate transmission line (slab line) by locating the center conductor 106 substantially at the center of the space between the pair of opposed parallel ground conductors 105a and 105b. FIG.
FIG. 8A shows a vertical section perpendicular to the slab line, and FIG.
(B) shows a vertical section parallel to the slab line. A slag 107 made of a metal piece is inserted into the slab line from above, and the slag 107 is horizontally (a direction parallel to the slab line) and vertical (a direction perpendicular to the slab line).
By changing the position of, an arbitrary impedance is generated. A signal is input to the mechanical tuner via the input coaxial terminal 108a, and the output coaxial terminal 10a.
A signal is output from the mechanical tuner via 8b.

That is, by adjusting the horizontal distance of the slug 107 from the input coaxial terminal 108a, the electrical length from the device under test 101 is changed, and the slug 107 is moved to the center conductor 1
06 is realized, and the short-circuit condition is realized. On the contrary, the slug 107 is sufficiently separated from the center conductor 106 to minimize the influence on the electromagnetic field of the line, thereby achieving 50Ω. In addition, since the device to be measured cannot be directly accessed from the coaxial line, a conversion structure for the device is required. There are several access means, and the conversion structure is generically called a test fixture.

When a conventional mechanical tuner having one slug is used as a load-pull measurement for a frequency multiplier, the impedance of the output tuner is measured by changing the impedance at the intended frequency of the harmonic. A multiplied wave load impedance that optimizes parameters such as output power is required.

[0008]

However, the multiplication conversion efficiency depends not only on the multiplied wave load impedance of the output circuit but also on the fundamental wave load impedance, and this must be optimized (short-circuit condition with a certain electrical length). Although the conventional mechanical tuner as described above realizes a short-circuit condition by bringing the slag close to the center conductor of the slab line, the short-circuit for the fundamental wave is different from that for the multiplied wave. Even so, short-circuiting still occurred, and it was not possible to optimize the multiplied wave load impedance. Also, when a certain multiplied wave load impedance is realized for a certain slug position, the fundamental wave load impedance has a certain value. As described above, the conventional mechanical tuner having one slug cannot control the fundamental wave load impedance and the multiplied wave load impedance independently.

Accordingly, the present invention provides a method for measuring the critical performance of a device as a frequency multiplier.
It is an object of the present invention to provide a frequency multiplier element characteristic evaluation method and an apparatus for controlling a multiplied wave load impedance independently with a fundamental wave load impedance set optimally.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a characteristic evaluation is performed by using a source-side measurement system including a source-side mechanical tuner used for adjusting a load impedance of a fundamental wave of an input signal. Supply the fundamental frequency signal to the target frequency multiplier, and use the load-side measurement system including the load-side mechanical tuner to adjust the load impedance of the output signal of the frequency multiplier. in frequency multiplication device measurement evaluation method for evaluating the frequency multiplication properties were collected data on approximately the separation gap parallel ground conductor pair of opposed
A slab line is formed by positioning the center conductor in the center
In this slab line, a multiplied wave load
Structure with a slag inserted as impedance control means.
Load the center of the slab line to the mechanical tuner on the load side.
Perpendicular to the body and one end in electrical contact and parallel
Quarter of the fundamental frequency held parallel to the ground conductor
By providing a central conductor having a length of one wavelength, it functions as an open-end stub of a quarter wavelength of the fundamental wave frequency, and therefore satisfies the short-circuit condition for the fundamental wave at that position,
And, form a load-side mechanical tuner with a fundamental load impedance control means for determining an electrical length of up to short-circuit point from the measuring device by its positioning, optimum fundamental load impedance by the fundamental load impedance control means , And in this state, the even-ordered harmonic load impedance is controlled.

Further, the invention according to claim 2 is based on a frequency multiplier (device under test 2) which includes a source side mechanical tuner (35) used for adjusting a load impedance of a fundamental wave of an input signal and which is subjected to characteristic evaluation. And a load-side measurement system (4) including a load-side mechanical tuner (41) used for adjusting a multiplied-wave load impedance of an output signal of the frequency-multiplier element. In the frequency multiplier measuring and evaluating apparatus (1) for collecting data on the frequency multiplier performance of the frequency multiplier and evaluating the frequency multiplier characteristics, the load-side mechanical tuner of the load-side measuring system includes a pair of opposed parallel ground conductors.
The center conductor is located approximately at the center of the
Form a rub line, and from this piece of metal during this slab line
As a means of controlling the load impedance of multiple harmonics
Function as an open-end stub of a quarter wavelength of the fundamental frequency, and therefore satisfy the short-circuit condition for the fundamental wave at that position, and set the short-circuit point from the device under test by setting its position. The above slab line is used as a fundamental wave load impedance control means (fundamental wave load impedance control probe 5) for determining the electrical length up to
Perpendicular to the center conductor and one end is in electrical contact,
And the fundamental frequency held parallel to the parallel ground conductor
Even Ru comprise a number of quarter wave length of the center conductor (51)
Cities, by the fundamental load impedance control means to optimally set the fundamental load impedance, characterized in that so as to control the even-order multiplier wave load impedance in that state.

[0012]

Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the present invention, as shown in FIG. 1, a frequency multiplier element characteristic evaluation apparatus 1 includes a source side measurement system 3 for supplying a fundamental frequency signal to a frequency multiplier element 2 to be evaluated, and a frequency of the frequency multiplier element 2. A load-side measurement system 4 for collecting data on the multiplication performance.

The source side measuring system 3 includes a signal source 31 for supplying a fundamental frequency signal, a directional coupler 32, an isolator 33, a device tee 34, and a source side mechanical tuner 3.
5 is included. The directional coupler 32 is for branching a fixed ratio (for example, 1/20 as the degree of coupling) of the signal from the signal source 31, and the signal level is measured by a power meter 36 to measure the signal level. The output level from 31 is monitored. The isolator 34 is for preventing the reflected wave from the device under test 2 from affecting the signal source 31. The bias tee 34 is used to supply a bias to the device under test 2. The source-side mechanical tuner 35 adjusts the load impedance of the input signal (fundamental frequency signal).

On the other hand, the load-side measuring system 4 includes a load-side mechanical tuner 41 having a function of adjusting a multiplied-wave load impedance of an output signal of the device under test 2, and a bias tee 42 used to supply a bias to the device under test 2. , And a spectrum analyzer 43. The spectrum analyzer 43 measures the level of a harmonic, a fundamental wave, and an unnecessary harmonic generated from the device under test 2.

Thus, the load-side mechanical tuner 41 of the frequency-multiplier element characteristic evaluation apparatus 1 according to the present embodiment uses the existing slug tuner (with the center conductor positioned substantially at the center of the space between the pair of opposed parallel ground conductors). (A structure in which a parallel plate transmission line (slab line) is formed and a slag made of metal pieces is inserted into this slab line from above)
"It functions as an open-ended stub of a quarter wavelength of the fundamental frequency, and therefore satisfies the short-circuit condition for the fundamental wave at that position, and, depending on the position setting, the distance from the device under test to the short-circuit point. A fundamental wave load impedance control probe functioning as "fundamental wave load impedance control means for determining the electrical length" is provided. The probe for controlling the load impedance of the fundamental wave thus configured has an open condition with respect to the even-numbered harmonics, and therefore has no influence on the control of the load impedance of the harmonics.

Accordingly, the control of the fundamental wave load impedance by setting the position of the probe for controlling the fundamental wave load impedance and the control of the multiplied wave load impedance by setting the position of the slug are performed independently, so that the reflection of the fundamental wave component is suppressed. In addition, it is possible to measure performance such as frequency-multiplied output power, conversion efficiency, power consumption, and phase noise that can be achieved by the device with respect to frequency multiplication, and conditions therefor.

Even when the fundamental wave load impedance control probe having the above-described configuration is provided in the load-side mechanical tuner 41, there is a limitation that the characteristic evaluation of the device under test 2 can be performed only with respect to even-order multiplication. However, doublers and quadruples are used rather frequently,
In particular, the frequency doubler is the most frequently used because it provides the highest conversion efficiency, so that it is extremely important to be able to evaluate the even-numbered multiplication characteristics.

Next, a configuration example of a fundamental wave load impedance control probe as fundamental wave load impedance control means will be described with reference to FIG.

The fundamental wave load impedance control probe 5 has a center conductor 51 of a quarter wavelength (with respect to the fundamental wave).
Is fixed by, for example, a low dielectric constant dielectric 52 formed in a rectangular parallelepiped, and conductor plates 53a and 53b are attached to a pair of opposed side surfaces of the low dielectric constant dielectric 52 in a rectangular parallelepiped, respectively. A structure for functioning as a thrust stub having an open end in the vertical direction (the direction of the center conductor 51) is provided. Styrofoam or the like can be used as the low dielectric constant dielectric 52, and a material having a dielectric constant close to 1 is suitable.

The fundamental wave load impedance control probe 5 configured as described above is connected to the load side mechanical tuner 4.
1 is inserted between the input coaxial terminal on the slab line and the slag, and is set at a position where the other end of the center conductor 51 reaches the center conductor of the slab line main line. The condition is fulfilled. As a position setting method, a micrometer is mounted on the upper part of the rectangular parallelepiped dielectric so that the vertical position can be finely adjusted.
Also, the position can be adjusted by a micrometer in the horizontal direction, and the electrical length from the device under test 2 to the short-circuit end can be optimized. The fine adjustment of the probe position in the vertical direction allows fine adjustment of the coupling state of the electromagnetic field with the center conductor of the slab line main line, so that the band as the band rejection filter can be varied.

Next, an embodiment in which the fundamental characteristics of the source pull at the fundamental frequency of the frequency multiplier and the load pull at the harmonic frequency of the frequency multiplier were examined using the frequency multiplier element characteristic evaluation apparatus 1 'as shown in FIG. explain.

An automatic mechanical tuner (Focu) is used as the source-side mechanical tuner 35 and the load-side mechanical tuner 41.
s Microwaves, model 4006, corresponding frequency: 6 to 40 GHz) was used. As a test fixture in which the device under test 2 is fixed, access to the on-wafer device is enabled by the RF probes 61 and 61. Each mechanical tuner is installed on a metal plate 63 attached to a probe station 62,
The semi-rigid coaxial cables 64, 64 connected the RF probes 61, 61, respectively. The probe station 62 is a SUM manufactured by Cascade Microtech.
MIT 9000 was used.

By controlling the source-side mechanical tuner 35 and the load-side mechanical tuner 41, it is assumed that an arbitrary value of impedance on the source side and on the load side viewed from the device under test 2 is generated. However, actually, due to the loss between the device under test 2 and each tuner,
The region of the generated impedance is limited. Therefore, it is important to minimize this loss and RF
As the probe 61, a pico probe manufactured by GGB, model 40M (insertion loss 0.5 dB or less at DC to 40 GHz) is used, and the semi-rigid coaxial cable 64 is Spe.
89-0090-KMKM manufactured by ctrum Co., Ltd. was used, and the length thereof was set to the minimum necessary length (9 cm).

The bias tees 34 and 42 used for supplying a bias to the device under test 2 are
The mechanical tuners 35 and 41 were placed outside from the viewpoint.
As the bias tees 34 and 42, K2 manufactured by Anritsu Corporation
50, the drain-source voltage was set to 3.0 V and the gate-source voltage was set to −1.2 V as the bias voltage. As the isolator 33, SMI-13 manufactured by SMT
16 was used. Krytar is used as the directional coupler 32.
Using 102040013K (2-40 GHz) manufactured by
The coupling degree is -13 dB.

The device under test 2 has a gate width of 50
0 μm Northrop Grumman GaAs
The PHEMT was pinched off, and the second harmonic generated from the element was measured by the spectrum analyzer 43. Since the insertion loss caused by the source-side mechanical tuner 35 varies depending on the impedance generated by the tuner, the output level of the signal source 31 is adjusted so that the power input to the device under test 2 becomes constant.

As shown in FIG. 4, the probe 5 for controlling the fundamental wave load impedance to be added to the mechanical tuner 41 on the load side is made of a foamed dielectric material having a dielectric constant of about 1 and having a rectangular parallelepiped (3.8 mm width × 3.8 mm). 7. Depth 7.5mm x height 8.
A copper wire having a thickness of 1.0 mm and a length of 9.0 mm was fixed as a central conductor 51 on the central axis of a low-dielectric-constant dielectric 52 formed to a thickness of 0 mm). This is Focus M
Microwaves automatic mechanical tuner (6-40
At the position between the input terminal and the slag on the slab line (GHz), the slab line was inserted vertically from the gap on the upper surface of the slab line, and fixed at a position such that the lower surface of the rectangular parallelepiped reached the center conductor of the slab line main line. The gap between the plates of the pair of parallel ground conductors constituting the slab line is 3.0 mm, but the low dielectric constant dielectric 52 formed of an elastic foamed dielectric material can be sufficiently inserted even with a width of 3.8 mm. And
In addition, the low dielectric constant dielectric material 5 is formed by the restoring force of the foamable dielectric material.
2 is in close contact with the inner surface of the parallel setting conductor between the plates, so that it can be fixed at a fixed position without separately providing fixing means.

The load-side mechanical tuner 4 loaded with the probe 5 for controlling the load impedance of the fundamental wave as described above.
The characteristics of No. 1 were measured using a vector network analyzer (manufactured by Hewlett-Packard Company, model number: HP8510C). FIG. 5 shows the characteristics when the slag is sufficiently separated from the center conductor (50Ω). That is, the probe 5 for controlling the load impedance of the fundamental wave has a frequency of 8.5 GHz.
Operates at a quarter wavelength, indicating that 8.5 GHz is almost totally reflected (the corresponding impedance is 2.76 Ω−j 7.0 Ω). At this time, the value of the impedance corresponding to the return loss of 17.0 GHz, which is the second harmonic, is 40.5Ω-j3.0Ω, which indicates that the transmission condition is almost maintained. FIG. 6 shows that the second harmonic impedance is changed, for example, by changing the position of the slug.
This is the case where it is set to 8.2Ω + 9.88Ω. The fundamental wave is also almost totally reflected, indicating that the corresponding impedance is almost unchanged (2.71Ω−j7.0Ω) and is not affected. Further, it was confirmed that the phase of the reflection coefficient was changed by changing the position of the probe 5 for controlling the load impedance of the fundamental wave while maintaining the condition of high reflection for the fundamental wave. These experimental results demonstrate that the harmonic load impedance can be controlled independently with the optimal setting of the fundamental load impedance.

Therefore, when performing load-pull measurement using the load-side mechanical tuner 41 loaded with the fundamental-wave load impedance control probe 5, after adjusting the source-side mechanical tuner 35 to the optimum source impedance, In the dynamic tuner 41, the control of the fundamental wave impedance by setting the position of the fundamental wave load impedance control probe 5 and the control of the multiplied wave impedance by setting the position of the slug are performed independently, so that the conversion efficiency of the doubled wave is maximized. What is necessary is just to find such a condition.

First, the input side tuner is controlled (source pull measurement) for the fundamental wave frequency f0 = 14.25 GHz while the load side is terminated at 50Ω, and the fundamental wave source impedance so that the conversion efficiency of the doubled wave is maximized. I asked.
Next, after the input side tuner is adjusted to this optimum source impedance, the output side tuner is controlled for 2f0 (load-pull measurement), and similarly, the second harmonic wave load impedance such that the conversion efficiency of the second harmonic wave is maximized. I asked.
The position control, measurement, and data collection of the source-side mechanical tuner 35 and the load-side mechanical tuner 41 are all performed by computer control.

As an example of the measurement result, a doubled wave output of 9.0 dBm was measured with respect to an input power of 8.0 dBm. At this time, the reflection coefficients corresponding to the fundamental wave source impedance and the doubled wave load impedance are each 0.1.
75/128 ° and 0.61 / 134 °.

[0031]

As described above, according to the method of measuring and evaluating a frequency doubler according to claim 1 of the present application, it functions as an open-end stub having a quarter wavelength of the fundamental wave frequency, and therefore, has a basic function at that position. A load-side mechanical tuner including a fundamental-wave load impedance control unit that satisfies a short-circuit condition for a wave and determines an electrical length from a device to be measured to a short-circuit point by setting the position thereof; By setting the fundamental wave load impedance optimally and controlling the even-ordered multiplied wave load impedance in that state, the fundamental wave load impedance and the multiplied wave load impedance can be controlled independently, and as a frequency multiplication element It is possible to carry out a characteristic evaluation that satisfactorily draws out the limit performance.

Further, according to the frequency multiplier measuring and evaluating apparatus of the present invention, it functions as an open-end stub having a quarter wavelength of the fundamental wave frequency. The load-side mechanical tuner of the load-side measurement system includes fundamental wave load impedance control means for satisfying and determining the electrical length from the device to be measured to the short-circuit point according to the position setting. Sets the fundamental wave load impedance by the fundamental wave load impedance control means,
In this state, the even-ordered multiplied wave load impedance can be controlled independently, so that it is possible to perform a characteristic evaluation that satisfactorily draws out the limit performance as a frequency multiplying element.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a frequency multiplier measuring and evaluating apparatus according to the present invention.

FIG. 2 is a schematic perspective view of a fundamental wave load impedance control probe as a fundamental wave load impedance control means.

FIG. 3 is a configuration diagram showing an embodiment of a frequency multiplier measuring and evaluating device.

FIG. 4 is a perspective view showing an example of a probe for controlling a load impedance of a fundamental wave.

FIG. 5 is a characteristic diagram showing a return loss characteristic of a load-side mechanical tuner loaded with a probe for controlling a fundamental wave load impedance when a slug is sufficiently separated from a center conductor.

FIG. 6 shows a second harmonic impedance of 78.2Ω + 9.88.
FIG. 9 is a characteristic diagram showing a return loss characteristic of a load-side mechanical tuner loaded with a probe for controlling a fundamental wave load impedance when set to Ω.

FIG. 7 is a schematic configuration diagram of a conventional frequency multiplier measuring and evaluating device.

FIG. 8 is a schematic explanatory view of a slab line in a conventional stub tuner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frequency-multiplier element measurement evaluation apparatus 2 Device under test 3 Source-side measurement system 35 Source-side mechanical tuner 4 Load-side measurement system 41 Load-side mechanical tuner 5 Probe for load impedance control of fundamental wave

Claims (2)

(57) [Claims] 1. A fundamental frequency signal is supplied from a source-side measurement system including a source-side mechanical tuner used for adjusting a fundamental-wave load impedance of an input signal to a frequency-multiplier element whose characteristics are to be evaluated. A frequency multiplier measuring and evaluating method for collecting data on the frequency multiplying performance of the frequency multiplier and evaluating the frequency multiplication characteristics by a load-side measurement system including a load-side mechanical tuner used for adjusting the multiplied wave load impedance of the output signal. Approximately in the center of the gap between the pair of opposed parallel ground conductors
A slab line is formed by positioning the core conductor,
Multiplier-wave load impedance consisting of metal slab in slab line
Load side of the structure with slag inserted as a resistance control means
For mechanical tuners, perpendicular to the center conductor of the above slab line
And one end is in electrical contact and a parallel ground conductor
Quarter wavelength of the fundamental frequency held parallel to
By providing a center conductor of length , it functions as an open-end stub of a quarter wavelength of the fundamental wave frequency, and therefore satisfies the short-circuit condition with respect to the fundamental wave at that position, and is covered by the position setting. A load-side mechanical tuner comprising fundamental wave load impedance control means for determining an electrical length from the measurement device to the short-circuit point is formed , and the fundamental wave load impedance is optimally set by the fundamental wave load impedance control means. A frequency multiplier element characteristic evaluation method, wherein an even-order multiple-wave load impedance is controlled. 2. A source-side measurement system including a source-side mechanical tuner used for adjusting a fundamental-wave load impedance of an input signal and supplying a fundamental-frequency signal to a frequency-multiplier element to be evaluated, and an output of the frequency-multiplier element A frequency-multiplier element measurement and evaluation device that includes a load-side measurement system including a load-side mechanical tuner used for adjusting the frequency-multiplied-wave load impedance of a signal, and collects data on the frequency-multiplier performance of the frequency-multiplier element and evaluates the frequency-multiplier characteristics. The load-side mechanical tuner of the load-side measurement system is located at the center of the space between the pair of opposing parallel ground conductors.
A slab line is formed by positioning the core conductor,
Multiplier-wave load impedance consisting of metal slab in slab line
A structure in which a slug is inserted as the impedance control means , which functions as an open-end stub of a quarter wavelength of the fundamental wave frequency, and therefore satisfies the short-circuit condition with respect to the fundamental wave at that position, and by setting its position. As fundamental wave load impedance control means for determining the electrical length from the device under test to the short-circuit point ,
Orthogonal and one end is in electrical contact and parallel ground
Quarter of the fundamental frequency held parallel to the conductor
Characterized in that the shall with a central conductor of the length of the wavelength, and to optimally set the fundamental load impedance by the fundamental load impedance control means, for controlling the even-order multiplier wave load impedance in that state Frequency multiplier element characteristic evaluation device.