JP4149428B2 - Vector network analyzer and calibration method thereof - Google Patents

Description

  The present invention relates to a phase measurement technique in a high frequency region (microwave band, millimeter wave band, submillimeter wave band, terahertz band), optical region (infrared ray, visible ray, ultraviolet ray) and the like.

The calibration of the current vector network analyzer (VNA) is performed by connecting several kinds of standard devices (short, open, load, through, line, etc.).
Japanese Patent No. 35409797

Conventional VNA calibration methods have a problem that the calibration procedure is complicated.
This calibration procedure is complicated and causes human error. In addition, it is necessary to connect and remove several kinds of standard devices at the time of calibration, which causes a problem of deterioration in measurement accuracy.

  The vector network analyzer according to the present invention is:
  An oscillation source that generates a high-frequency signal;
  A power distributor that distributes the output of the oscillation source in two;
  A 6-port junction comprising two input ports 1 and 2 and 4 power measurement output ports 3 to 6 for receiving a wave from one of the power distributors at the input port 1;
  A detector for detecting each of the waves output from the output ports 3 to 6 of the 6-port junction;
  Receiving a wave from the other of the power distributor and changing its phase;
  A first switch that receives the wave exiting the phase shifter and exits it to either the outlet (1) or (2);
  A second switch that selects any one of the inlets (1) and (2) and puts the wave that enters the inlet into the input port 2 of the 6-port junction;
  It has four ends, one end is connected to the outlet (1) of the first switch, the other end is connected to the inlet (1) of the second switch, and the other end is A first directional coupler connected to the first non-reflective terminator, the remaining one end being the measurement port P1,
  It has four ends, one end is connected to the outlet (2) of the first switch, the other end is connected to the inlet (2) of the second switch, and the other end is A second directional coupler connected to the second non-reflecting terminator and having the remaining one end serving as the measurement port P2 is provided.

According to the vector network analyzer and the calibration method thereof according to the present invention , one standard phase shifter and one standard reference having a known complex reflection coefficient can be used without performing complicated procedures as in the calibration method in the conventional vector network analyzer . Thus, the calibration accuracy can be improved, and the error in calculating the S parameter can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the embodiment of the present invention, as shown in FIG. 1, a 6-port junction 16, a detector 11, switches SW1, 13 and SW2, 14, directional couplers 22, 23, a power distributor 26, an oscillation source 21, By using the phase shifter 15 and the non-reflection terminators 24 and 25, a homodyne VNA different from the measurement principle of the conventional heterodyne VNA is realized. Hereinafter, this VNA is referred to as a 6-port VNA, and measurement port 1 of this 6-port VNA is represented as port P1, and measurement port 2 is represented as port P2.

The 6-port junction 16 will be further described. The 6-port joint itself is known.
The 6-port junction 16 is a device for high frequency measurement. The 6-port junction 16 is a measurement device that derives the amplitude ratio and phase difference (vector quantity) of two waves from hardware-specific information (calibration parameters) obtained by calibration and a plurality of power measurement values (scalar quantities). It is. The 6-port junction 16 can be used for either a reflectometer as shown in FIG. 2 or a correlator as shown in FIG. A reflectometer is a device that measures the complex reflection coefficient of a device under test (DUT), and a correlator is a device that measures the complex amplitude ratio of two waves.

  In FIG. 2, an oscillation source 19 is connected to port 1, and a 1-port device under test (DUT) 18 is connected to port 2. ₂ Enter the wave a ₂ That is, the complex reflection coefficient γ as seen from the port 2 to the 1-port DUT 18 side
    γ = a ₂ / B ₂   (1)
Measure.
  In FIG. 3, the wave a input from port 1 ₁ And wave input from port 2 ₂ Complex amplitude ratio W
    W = a ₂ / A ₁   (2)
Measure.
  Wave b output from a 6-port junction under conditions where the circuit is linear and only a single mode propagates _Three , B _Four , B _Five , B ₆ Is the wave a that is input to and output from ports 1 and 2 ₁ , A ₂ , B ₂ It can be expressed by a linear combination of
  That is, b _i (I = 3,4,5,6) is a ₁ , A ₂ , B ₂ Using,
    b _i = A _i a ₁ + B _i a ₂     (3)
    b _i = C _i a ₂ + D _i b ₂     (4)
Can be expressed as
  However, A _i , B _i , C _i , D _i Is a complex constant that depends on the frequency inherent to the 6-port junction.
  The power measured by the detector connected to port i is P _i Then, P _i Is the output wave b _i Is proportional to the square of the amplitude of. If α is a proportional constant,
    P _i = Α | A _i a ₁ + B _i a ₂ ｜ ²         (5)
    P _i = Α | C _i a ₂ + D _i b ₂ ｜ ²     (6)
Can be expressed as
  And the power ratio of port h (h = 4, 5, 6) to port 3 _Three P _h Is

It is expressed as this _Three T _h , T _h , _Three K _h , K _h Is a calibration parameter obtained by calibration.

In the embodiment of the present invention, a known integral calibration method (T. Yakabe, et al., IEEE IM, vol. 4) is used for each of four circuit states for measuring S ₁₁ , S ₁₂ , S ₂₁ , and S ₂₂ . 50, no.2 pp377-380, Apr. 2001) and calculate the four calibration parameters.
Using the calculated four calibration parameters, D ₁₁ S ₁₁ , S ₁₂ , S ₂₁ and S ₂₂ are measured from the power measurement value (scalar amount) by the detector 11. That is, when S ₁₁ measured using the calibration parameters calibrated for S ₁₁ measured, the calibration parameters at S ₁₂ measured using the calibration parameters calibrated for S ₁₂ measurements, the time S ₂₁ measurements calibrated for S ₂₁ measured use, at the time of S ₂₂ measured using the calibration parameters calibrated for measuring S _22.

FIG. 4 shows a circuit state when calculating calibration parameters for S ₁₁ measurement of the 2-port DUT 17. The switches SW1 and 13 are connected to the contact (1), the switches SW2 and 14 are connected to the contact (1), and the known standard 12 is connected to the port P1. This state corresponds to the 6-port reflectometer shown in FIG. In this state, after fixing the movable part of the phase shifter 15 to the starting position, the power of P _{3 to} P ₆ of the detector 11 is measured and used as a reference.
Next, while moving the movable part of the phase shifter 15, the power of P _{3 to} P ₆ of the detector 11 is measured for one period.
Calculating the S ₁₁ calibration parameters ₃ K ₄ for _{measuring, 3 K 5, 3 K 6} , k 3, k 4, k 5, k 6 of the two-port DUT17 using more power measurements.

FIG. 6 shows a circuit state when calculating calibration parameters for S ₁₂ measurement of the 2-port DUT 17. The switches SW1 and 13 are connected to the contact (2), the switches SW2 and 14 are connected to the contact (1), and the port P1 and the port P2 are directly connected. This state corresponds to the 6-port correlator shown in FIG. In this state, after fixing the movable part of the phase shifter 15 to the starting position, the power of P _{3 to} P ₆ of the detector 11 is measured and used as a reference.
Next, while moving the movable part of the phase shifter 15, the power of P _{3 to} P ₆ of the detector 11 is measured for one period.
The calibration parameters ₃ T ₄ , ₃ T ₅ , ₃ T ₆ , t ₃ , t ₄ , t ₅ , t ₆ for the S ₁₂ measurement of the 2-port DUT 17 are calculated using the above power measurement values.

FIG. 8 shows a circuit state when calculating calibration parameters for S ₂₁ measurement of the 2-port DUT 17. The switches SW1 and 13 are connected to the contact (1), the switches SW2 and 14 are connected to the contact (2), and the port P1 and the port P2 are directly connected. This state corresponds to the 6-port correlator shown in FIG. In this state, after fixing the movable part of the phase shifter 15 to the starting position, the power of P _{3 to} P ₆ of the detector 11 is measured and used as a reference.
Next, while moving the movable part of the phase shifter 15, the power of P _{3 to} P ₆ of the detector 11 is measured for one period.
Using the above power measurement values, calibration parameters ₃ T ₄ ′, ₃ T ₅ ′, ₃ T ₆ ′, t ₃ ′, t ₄ ′, t ₅ ′, t ₆ ′ for S ₂₁ measurement of the 2-port DUT 17 are set. calculate.

FIG. 10 shows a circuit state when calculating calibration parameters for S ₂₂ measurement of the 2-port DUT 17. The switches SW1 and 13 are connected to the contact (2), the switches SW2 and 14 are connected to the contact (2), and the known standard 12 is connected to the port P2. This state corresponds to the 6-port reflectometer shown in FIG. In this state, after fixing the movable part of the phase shifter 15 to the starting position, the power of P _{3 to} P ₆ of the detector 11 is measured and used as a reference.
Next, while moving the movable part of the phase shifter 15, the power of P _{3 to} P ₆ of the detector 11 is measured for one period.
Using the above measured power values, calibration parameters ₃ K ₄ ′, ₃ K ₅ ′, ₃ K ₆ ′, k ₃ ′, k ₄ ′, k ₅ ′, k ₆ ′ for S ₂₂ measurement of the 2-port DUT 17 are set. calculate.
By the procedure described above, the 6-port VNA can be calibrated easily and with high accuracy as compared with the conventional calibration method.

It is a figure which shows the structure of the vector network analyzer (VNA) which concerns on embodiment of invention. It is explanatory drawing of the reflectometer using 6 port junction. It is explanatory drawing of the correlator using 6 port junction. S according to the embodiment of the invention ₁₁ It is a figure which shows the connection of VNA for measuring the calibration parameter for a measurement. It is a reflectometer using 6 port junction corresponding to the connection of FIG. According to an embodiment of the invention, showing the connection of the VNA to measure the calibration parameters for S ₁₂ measurements. . FIG. 7 is a correlator using a 6-port junction corresponding to the connection of FIG. According to an embodiment of the invention, showing the connection of the VNA to measure the calibration parameters for S ₂₁ measurements. . It is a correlator using 6 port junction corresponding to the connection of FIG. S according to the embodiment of the invention _{twenty two} It is a figure which shows the connection of VNA for measuring the calibration parameter for a measurement. It is the reflectometer using 6 port junction corresponding to the connection of FIG.

Explanation of symbols

1, 2, 3, 4, 5, 6 Port 1 to Port 6
11 detector 12 standard device 13, 14 switch 15 phase shifter 16 6-port junction 17 DUT (2-port test device)
18 DUT (1 port EUT)
19, 20, 21 Oscillation source 22, 23 Directional coupler 24, 25 Non-reflective terminator 26 Power distributor

Claims (2)

  An oscillation source that generates a high-frequency signal;
  A power distributor that distributes the output of the oscillation source in two;
  A 6-port junction comprising two input ports 1 and 2 and 4 power measurement output ports 3 to 6 for receiving a wave from one of the power distributors at the input port 1;
  A detector for detecting each of the waves output from the output ports 3 to 6 of the 6-port junction;
  Receiving a wave from the other of the power distributor and changing its phase;
  A first switch that receives the wave exiting the phase shifter and exits it to either the outlet (1) or (2);
  A second switch that selects any one of the inlets (1) and (2) and puts the wave that enters the inlet into the input port 2 of the 6-port junction;
  It has four ends, one end is connected to the outlet (1) of the first switch, the other end is connected to the inlet (1) of the second switch, and the other end is A first directional coupler connected to the first non-reflective terminator, the remaining one end being the measurement port P1,
  It has four ends, one end is connected to the outlet (2) of the first switch, the other end is connected to the inlet (2) of the second switch, and the other end is A vector network analyzer comprising: a second directional coupler connected to the second non-reflecting terminator and having the remaining one end serving as a measurement port P2.   An oscillation source that generates a high-frequency signal;
  A power distributor that distributes the output of the oscillation source in two;
  A 6-port junction comprising two input ports 1 and 2 and 4 power measurement output ports 3 to 6 for receiving a wave from one of the power distributors at the input port 1;
  A detector for detecting each of the waves output from the output ports 3 to 6 of the 6-port junction;
  Receiving a wave from the other of the power distributor and changing its phase;
  A first switch that receives the wave exiting the phase shifter and exits it to either the outlet (1) or (2);
  A second switch that selects any one of the inlets (1) and (2) and puts the wave that enters the inlet into the input port 2 of the 6-port junction;
  It has four ends, one end is connected to the outlet (1) of the first switch, the other end is connected to the inlet (1) of the second switch, and the other end is A first directional coupler connected to the first non-reflective terminator, the remaining one end being the measurement port P1,
  It has four ends, one end is connected to the outlet (2) of the first switch, the other end is connected to the inlet (2) of the second switch, and the other end is A vector network analyzer calibration method comprising: a second directional coupler connected to a second non-reflecting terminator, and the remaining one end serving as a measurement port P2.
  Select the outlet (1) with the first switch, select the inlet (1) with the second switch, connect a known standard to the measurement port P1, and move the movable part of the phase shifter While measuring the power of the detector for one period, using the obtained power measurement value, S ₁₁ Calculating calibration parameters for measurement;
  The outlet (2) is selected by the first switch, the inlet (1) is selected by the second switch, the measurement ports P1 and P2 are directly connected, and the detection part is moved while moving the movable part of the phase shifter. Measure the power of the instrument for one cycle and use the power measurement value ₁₂ Calculating calibration parameters for measurement;
  The outlet (1) is selected by the first switch, the inlet (2) is selected by the second switch, the measurement ports P1 and P2 are directly connected, and the detection part is moved while moving the movable part of the phase shifter. Measure the power of the instrument for one cycle and use the power measurement value _{twenty one} Calculating calibration parameters for measurement;
  The outlet (2) is selected by the first switch, the inlet (2) is selected by the second switch, a known standard is connected to the measurement port P2, and the movable part of the phase shifter is moved. While measuring the power of the detector for one period, using the obtained power measurement value, S _{twenty two} A vector network analyzer calibration method comprising: calculating calibration parameters for measurement.

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