High frequency probe for examining electric characteristics of devices

• US 6,617,864 B2
• Filed: 12/20/2000
• Issued: 09/09/2003
• Est. Priority Date: 02/25/2000
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Iwamoto, Naofumi, Aso, Takeshi, Suetsugu, Takumi, Inoue, Akira, Katoh, Takayuki
• Primary Examiner(s): Cuneo, Kamand
• Assistant Examiner(s): PATEL, PARESH H
• Application Number:
  US09/739,970
• Publication Number:
  US 20010017549A1
• Time in Patent Office: 993 Days
• Field of Search: 324/540, 324/158.1, 324/762, 324/72.5, 324/686, 324/149, 324/754, 333/33, 333/34, 439/482
• US Class Current: 324/750.27
• CPC Class Codes: G01R 1/06733 Geometry aspects G01R1/06727 takes precedence
• CPC Class Codes: G01R 1/06766 Input circuits therefor
• CPC Class Codes: G01R 1/06772 High frequency probes

Abstract

A probe whose characteristic impedance can be accurately adjusted to a desired value with the production of a small number of prototypes. The probe includes a first line with a signal terminal to be connected to a signal electrode of a circuit to be measured and at least one first region connected to the signal terminal and to which one end of a chip capacitor is connected, a second line connected to a terminal of the first line and a junction to be connected to a measuring instrument at the remaining terminal, and an impedance matched to a characteristic impedance of the measuring instrument, a ground connector with a ground terminal to be connected to the ground electrode of the circuit to be measured, and at least one second region connected to the ground terminal and on which the remaining terminal of the chip capacitor is mounted in one-to-one correspondence with the first region. The impedance of the probe viewed from the circuit to be measured is provided by the chip capacitor mounted at specified positions within the first region and the second region.

Claims

1. A high-frequency signal probe for testing a circuit, the probe comprising:

a chip capacitor;

a signal terminal to be connected to a signal electrode of a circuit to be measured;

a first line that has an impedance, first and second ends, a length extending between the first and second ends, and a first capacitor mounting region extending along part of the length of the first line and transverse the length of the first line for mounting and connecting the chip capacitor to the first line at a plurality of positions along the first line for adjusting a characteristic impedance of the probe, the first end being connected to the signal terminal, and a first terminal of the chip capacitor being mounted on the first capacitor mounting region;

a second line connected to the second end of the first line, remote from the signal terminal, and having a junction to be connected to a measuring instrument for electrical testing, and an impedance matched to a characteristic impedance of the measuring instrument;

a ground terminal to be connected to a ground electrode of the circuit to be measured; and

a ground conductor connected to the ground terminal and having at least one second capacitor mounting region extending opposite and parallel to the first capacitor mounting region for connecting the chip capacitor at a plurality of positions for adjusting the characteristic impedance of the probe and to which a second terminal of the chip capacitor is mounted, wherein the chip capacitor has a specified capacitance and is mounted at positions within the first capacitor mounting region and the second capacitor mounting region so that the characteristic impedance of the probe, viewed from the circuit to be measured, has a desired value.

2. The probe for a high-frequency signal as claimed in claim 1, wherein

the ground conductor is formed on an insulating substrate having a back surface ground conductor and a plurality of via holes connected to the back surface ground conductor; and

an interval between each of the via holes and the signal terminal and an interval between via holes are each not greater than one-fourth of a wavelength λ

of a high-frequency signal input to the signal terminal.

3. The probe for a high-frequency signal as claimed in claim 1, including a chip inductor inserted in the first line.

4. The probe for a high-frequency signal as claimed in claim 1, including a line that is branched from the ground conductor as the second region, wherein the chip capacitor is connected across the branched line and the first region, and the branched line and the chip capacitor form an LC resonant circuit that resonates at a harmonic of a multiple of the frequency of a signal input to the signal terminal.

5. The probe for a high-frequency signal as claimed in claim 1, further comprising a high-impedance branch line branching from the first line proximate the signal terminal and having a terminal for detecting a potential of the signal terminal.

6. The probe for a high-frequency signal as claimed in claim 1, further comprising an isolator that has impedance characteristics corresponding to the frequency of a signal input between the first line and the second line, the impedance characteristics being identical to an isolator provided in an output section of the circuit to be measured.

7. The probe for a high-frequency signal as claimed in claim 1, further comprising a conductor connected to the ground conductor and shielding electromagnetic waves by covering the first line and the second line at a gap.