EP0911637A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Signal processing circuit for electro-optic probe

Assignee: Yokogawa Electric Corp

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Filing: 1998-10-21

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Granted: —

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Expires: 2018-10-21

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Abstract

Abstract A signal processing circuit is provided for an electro-optic probe, which is used to perform testing of a printed-circuit board for high-speed processing. Herein, a head portion of the electro-optic probe is mainly constructed by an electro-optic crystal (e.g., Bi 12 SiO 20 ), a multilayer dielectric mirror and a metal pin. When the metal pin is brought into contact with a signal line laid on the printed-circuit board, an electric field is caused to occur at the metal pin and is connected with the electro-optic crystal. Due to Pockel's effect, a birefringence ratio of the electro-optic crystal is varied in response strength of the connected electric field. So, when a laser beam is incident on the electro-optic crystal, it is changed in polarization and is reflected by the multilayer dielectric mirror. The reflected laser beam is split into two beams, which are then converted to electric signals. An amplification circuit performs differential amplification on the electric signals output from the electro-optic probe. An analog-to-digital conversion circuit converts output of the amplification circuit to digital data. In order to improve amplification efficiency for output of the electro-optic probe, an optimum frequency band is set to the amplification circuit while an optimum sampling timing is set to the analog-to-digital conversion circuit. The optimum frequency band and optimum sampling timing are determined such that output of the analog-to-digital conversion circuit becomes maximal.

Inventors

👤 Nobuaki c/o Ando Electric Co. Ltd. Takeuchi
👤 Yoshiki c/o Ando Elec. Co. Ltd. Yanagisawa
👤 Jun c/o Ando Elec. Co. Ltd. Kikuchi
👤 Yoshio c/o Ando Elec. Co. Ltd. Endou
👤 Mitsuru Nippon Telegr. and Tel. Corp. Shinagawa
👤 Tadao Nippon Telegr. and Tel. Corp. Nagatsuma
👤 Kazuyoshi Matsuhiro

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-01 20:49

CPC Classifications

G; G01; G01R; G01R1/00; G01R1/02; G01R1/06; G01R1/067; G01R1/07; G01R13/00; G01R13/02; G01R13/0281

Claims Analysis

Total Claims: 6

Claim 1

Independent Claim 92 words

A signal processing circuit for an electro-optic probe, comprising: amplification means for amplifying an output signal of the electro-optic probe; analog-to-digital conversion means for performing sampling on output of the amplification means so as to convert it to digital data; sampling timing detection means for sequentially changing sampling timings of the analog-to-digital conversion means so as to detect a sampling timing that an output value of the analog-to-digital conversion means becomes maximal; and setting means for setting the sampling timing detected by the sampling timing detection means to the analog-to-digital conversion means.

Claim 2

Dependent Claim 90 words

A signal processing circuit for an electro-optic probe, comprising: amplification means for amplifying an output signal of the electro-optic probe; analog-to-digital conversion means for performing sampling on output of the amplification means so as to convert it to digital data; frequency band detection means for sequentially changing frequency bands of the amplification means so as to detect a frequency band that an output value of the analog-to-digital conversion means becomes maximal; and setting means for setting the frequency band detected by the frequency band detection means to the amplification means.

Claim 3

Dependent Claim 94 words

A signal processing circuit for an electro-optic probe, comprising: amplification means for amplifying an output signal of the electro-optic probe; analog-to-digital conversion means for performing sampling on output of the amplification means so as to convert it to digital data; sampling timing detection means for sequentially changing sampling timings of the analog-to-digital conversion means so as to detect a sampling timing that a S/N ratio of output of the analog-to-digital conversion means becomes maximal; and setting means for setting the sampling timing detected by the sampling timing detection means to the analog-to-digital conversion means.

Claim 4

Dependent Claim 92 words

A signal processing circuit for an electro-optic probe, comprising: amplification means for amplifying an output signal of the electro-optic probe; analog-to-digital conversion means for performing sampling on output of the amplification means so as to convert it to digital data; frequency band detection means for sequentially changing frequency bands of the amplification means so as to detect a frequency band that a S/N ratio of output of the analog-to-digital conversion means becomes maximal; and setting means for setting the frequency band detected by the frequency band detection means to the amplification means.

Claim 5

Dependent Claim 152 words

A signal processing circuit comprising: laser beam generation means for generating a laser beam; an electro-optic probe for introducing the laser beam therein when being brought into contact with a measured object, so that the electro-optic probe provides a reflected laser beam, based on which two laser beams are derived and are converted to electric signals respectively; amplification means for performing differential amplification on the electric signals output from the electro-optic probe; analog-to-digital conversion means for converting output of the amplification means to digital data; sampling timing determination means for determining an optimum sampling timing such that output of the analog-to-digital conversion means becomes maximal, so that the optimum sampling timing is set to the analog-to-digital conversion means; and frequency band determination means for determining an optimum frequency band such that the output of the analog-to-digital conversion means becomes maximal, so that the optimum frequency band is set to the amplification means.

Claim 6

Dependent Claim 17 words

A signal processing circuit according to claim 5, wherein the measured object corresponds to a printed-circuit board.

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