US20020017951A1 - Preamplification circuit - Google Patents
Preamplification circuit Download PDFInfo
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- US20020017951A1 US20020017951A1 US09/852,738 US85273801A US2002017951A1 US 20020017951 A1 US20020017951 A1 US 20020017951A1 US 85273801 A US85273801 A US 85273801A US 2002017951 A1 US2002017951 A1 US 2002017951A1
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- feedback resistor
- switching means
- resistance value
- signal
- input signal
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- 239000003990 capacitor Substances 0.000 claims abstract description 31
- 238000009738 saturating Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/01—Shaping pulses
- H03K5/02—Shaping pulses by amplifying
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G1/00—Details of arrangements for controlling amplification
- H03G1/0005—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal
- H03G1/0088—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using discontinuously variable devices, e.g. switch-operated
Definitions
- the present invention relates to a preamplification circuit that controls large signal inputs.
- FIG. 1 is a circuit diagram showing a configuration example of a conventional preamplification circuit.
- this conventional example comprises inverse amplifier 1 for amplifying and outputting a preamp input signal, buffer circuit 2 for buffering and outputting the signal outputted from inverse amplifier 1 , feedback resistors 3 and 4 connected in parallel to each other between the input terminal of inverse amplifier 1 and the output terminal of buffer circuit 2 for changing the gain of inverse amplifier 1 , phase compensation capacitor 7 connected between the input terminal and output terminal of inverse amplifier 1 for compensating the phase of inverse amplifier 1 , FET switch 5 for switchng the connection between feedback resistor 4 and inverse amplifier 1 , buffer circuit 2 based on a gain switching signal supplied and FET switch 6 for switching between charge/discharge of phase compensation capacitor 7 based on the gain switching signal.
- the signal outputted from buffer circuit 2 is outputted as a preamp output signal (see Japanese Patent Laid-Open No. 1997-8563).
- the gain switching signal is fixed to LOW while the preamp input signal stays at a low level, which keeps OFF FET switch 5 .
- feedback resistor 3 is the only feedback resistor to control the gain of inverse amplifier 1 .
- FET switch 6 is turned OFF, and therefore phase compensation capacitor 7 is left open and discharged, and phase compensation is not performed using phase compensation capacitor 7 for inverse amplifier 1 .
- the gain switching signal is HIGH, which turns ON FET switch 5 .
- feedback resistors 3 and 4 function as the feedback resistors to control the gain of inverse amplifier 1 .
- the gain of inverse amplifier 1 becomes smaller than when the preamp input signal stays at a low level.
- FET switch 6 turns ON, which causes phase compensation capacitor 7 to be charged with the preamp input signal, and in this way, phase compensation is performed for inverse amplifier 1 .
- phase compensation capacitor 7 starts when the gain switching signal changes from LOW to HIGH.
- phase compensation capacitor 7 starts at the timing at which the preamp input signal changes from a low level signal to a high level signal and the gain switching signal changes from LOW to HIGH.
- the amount of discharge of phase compensation capacitor 7 increases, and then when the preamp input signal becomes a high level signal and the gain switching signal becomes HIGH, a high current is pulled into inverse amplifier 1 . This introduces large noise to the preamp output signal, causing a problem of adversely affecting the circuits that follow.
- first switching means when an input signal having a lower level than a predetermined threshold is supplied, first switching means performs control in such a way that the first feedback resistor is the only feedback resistor connected to amplifying means and the gain of the amplifying means is controlled only by the first feedback resistor. Then, when the input signal has a higher level than the predetermined threshold, the first switching means performs control in such a way that the feedback resistors connected to the amplifying means become the first and second feedback resistors connected in parallel to each other, thereby the gain of the amplifying means is controlled by the resistance value of the first and second feedback resistors connected in parallel. This allows the amplifying means to keep linearity without saturating even when the input signal changes from a lower level than the predetermined threshold to a higher level than the predetermined threshold.
- the phase compensation capacitor is charged under the control of the second switching means for phase compensation of the amplifying means.
- the phase compensation capacitor is charged at predetermined timing under the control of third switching means, preventing a high current from being pulled into the amplifying means when the input signal changes from a lower level than the predetermined threshold to a higher level than the predetermined threshold, thus reducing noise applied to the output signal.
- FIG. 1 is a circuit diagram showing a configuration example of a conventional preamplification circuit
- FIG. 2 is a timing chart to explain an operation of the preamplification circuit shown in FIG. 1;
- FIG. 3 is a circuit diagram showing a first embodiment of the preamplification circuit of the present invention.
- FIG. 4 is a timing chart to explain an operation of the preamplification circuit shown in FIG. 3.
- FIG. 5 is a circuit diagram showing a second embodiment of the preamplification circuit of the present invention.
- this embodiment comprises inverse amplifier 1 for amplifying and outputting a preamp input signal, buffer circuit 2 for buffering and outputting the signal outputted from inverse amplifier 1 , first and second feedback resistors 3 and 4 connected in parallel to each other between the input terminal of inverse amplifier 1 and the output terminal of buffer circuit 2 for changing the gain of inverse amplifier 1 , phase compensation capacitor 7 connected between the input terminal and output terminal of inverse amplifier 1 for compensating the phase of inverse amplifier 1 , FET switch 5 as first switching means for switching the connection between the feedback resistor 4 and inverse amplifier 1 , buffer circuit 2 based on a gain switching signal supplied, FET switch 6 as second switching means for switching between charge/discharge of phase compensation capacitor 7 based on the gain switching signal or a reset signal and an OR gate 8 as third switching means, whose input terminal is supplied the gain switching signal and the reset signal and output terminal is connected to the gate of FET switch 6 .
- a signal outputted from buffer circuit 2 is outputted as a preamp output signal.
- the reset signal becomes HIGH for every data supplied and then the data is supplied.
- phase compensation capacitor 7 This causes phase compensation capacitor 7 to be charged every time the preamp input signal is supplied even when the gain switching signal is LOW, which means that the amount of discharge of phase compensation capacitor 7 will no longer increase.
- the gain switching signal becomes HIGH, which turns ON FET switch 5 .
- the gain of inverse amplifier 1 is controlled by feedback resistors 3 and 4 and the signal amplified with the gain is outputted as the preamp output signal. That is, the gain of inverse amplifier 1 becomes smaller than when the preamp input signal has a lower level than the predetermined threshold. As a result, inverse amplifier 1 keeps linearity without saturating.
- the HIGH level of the gain switching signal is transmitted to the gate of FET switch 6 via OR gate 8 , which turns ON FET switch 6 causing phase compensation capacitor 7 to be charged.
- phase compensation capacitor 7 is charged by the HIGH level of the reset signal every time the preamp input signal is supplied, preventing any high current from being pulled into inverse amplifier 1 and preventing noise from applying to the preamp output signal.
- FET switches 5 and 6 are used as the first and second switching means, but the present invention is not limited to this and other switches can also be used.
- this embodiment comprises inverse amplifier 1 for amplifying and outputting a preamp input signal, buffer circuit 2 for buffering and outputting the signal outputted from inverse amplifier 1 , first and second feedback resistors 3 and 4 connected in parallel to each other between the input terminal of inverse amplifier 1 and the output terminal of buffer circuit 2 for changing the gain of inverse amplifier 1 , phase compensation capacitor 7 connected between the input terminal and output terminal of inverse amplifier 1 for compensating the phase of inverse amplifier 1 , FET switch 5 as first switching means for switching the connection between the feedback resistor 4 and inverse amplifier 1 , buffer circuit 2 based on a gain switching signal supplied, FET switch 6 as second switching means for switching between charge/discharge of phase compensation capacitor 7 based on the gain switching signal and an FET switch 9 as third switching means for switching between charge/discharge of phase compensation capacitor 7 based on a reset signal that becomes HIGH every time a preamp input signal is supplied.
- a signal outputted from buffer circuit 2 is outputted as a preamp output signal.
- the reset signal becomes HIGH for every data supplied and then the data is supplied.
- phase compensation capacitor 7 This causes phase compensation capacitor 7 to be charged every time the preamp input signal is supplied even when the gain switching signal is LOW, which means that the amount of discharge of phase compensation capacitor 7 will no longer increase.
- the gain switching signal becomes HIGH, which turns ON FET switch 5 .
- the gain of inverse amplifier 1 is controlled by feedback resistors 3 and 4 and the signal amplified with the gain is outputted as the preamp output signal. That is, the gain of inverse amplifier 1 becomes smaller than when the preamp input signal has a lower level than the predetermined threshold. As a result, inverse amplifier 1 keeps linearity without saturating.
- the HIGH level of the gain switching signal is transmitted to the gate of FET switch 6 , which turns ON FET switch 6 causing phase compensation capacitor 7 to be charged.
- phase compensation capacitor 7 is charged by the HIGH level of the reset signal every time the preamp input signal is supplied, preventing any high current from being pulled into inverse amplifier 1 and preventing noise from applying to the preamp output signal.
- FET switches 5 , 6 and 9 are used as the first to third switching means, but the present invention is not limited to this and other switches can also be used.
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Amplifiers (AREA)
- Control Of Amplification And Gain Control (AREA)
Abstract
Description
- 1. Field of the Invention
- The present invention relates to a preamplification circuit that controls large signal inputs.
- 2. Description of the Related Art
- FIG. 1 is a circuit diagram showing a configuration example of a conventional preamplification circuit.
- As shown in FIG. 1, this conventional example comprises
inverse amplifier 1 for amplifying and outputting a preamp input signal,buffer circuit 2 for buffering and outputting the signal outputted frominverse amplifier 1,feedback resistors inverse amplifier 1 and the output terminal ofbuffer circuit 2 for changing the gain ofinverse amplifier 1,phase compensation capacitor 7 connected between the input terminal and output terminal ofinverse amplifier 1 for compensating the phase ofinverse amplifier 1,FET switch 5 for switchng the connection betweenfeedback resistor 4 andinverse amplifier 1,buffer circuit 2 based on a gain switching signal supplied andFET switch 6 for switching between charge/discharge ofphase compensation capacitor 7 based on the gain switching signal. The signal outputted frombuffer circuit 2 is outputted as a preamp output signal (see Japanese Patent Laid-Open No. 1997-8563). - In the preamplification circuit in the above described configuration, the gain switching signal is fixed to LOW while the preamp input signal stays at a low level, which keeps
OFF FET switch 5. As a result,feedback resistor 3 is the only feedback resistor to control the gain ofinverse amplifier 1. Furthermore,FET switch 6 is turned OFF, and thereforephase compensation capacitor 7 is left open and discharged, and phase compensation is not performed usingphase compensation capacitor 7 forinverse amplifier 1. - On the other hand, while the preamp input signal stays at a high level, the gain switching signal is HIGH, which turns ON
FET switch 5. In this way,feedback resistors inverse amplifier 1. As a result, the gain ofinverse amplifier 1 becomes smaller than when the preamp input signal stays at a low level. Furthermore,FET switch 6 turns ON, which causesphase compensation capacitor 7 to be charged with the preamp input signal, and in this way, phase compensation is performed forinverse amplifier 1. - In the conventional preamplification circuit above, charging to
phase compensation capacitor 7 starts when the gain switching signal changes from LOW to HIGH. - As shown in FIG. 2, in this conventional example, charging to
phase compensation capacitor 7 starts at the timing at which the preamp input signal changes from a low level signal to a high level signal and the gain switching signal changes from LOW to HIGH. However, if input of the low level signal persists long time, the amount of discharge ofphase compensation capacitor 7 increases, and then when the preamp input signal becomes a high level signal and the gain switching signal becomes HIGH, a high current is pulled intoinverse amplifier 1. This introduces large noise to the preamp output signal, causing a problem of adversely affecting the circuits that follow. - It is an object of the present invention to provide a preamplification circuit capable of reducing noise applied to a preamp output signal when the preamp input signal changes from a low level signal to a high level signal.
- In the present invention, when an input signal having a lower level than a predetermined threshold is supplied, first switching means performs control in such a way that the first feedback resistor is the only feedback resistor connected to amplifying means and the gain of the amplifying means is controlled only by the first feedback resistor. Then, when the input signal has a higher level than the predetermined threshold, the first switching means performs control in such a way that the feedback resistors connected to the amplifying means become the first and second feedback resistors connected in parallel to each other, thereby the gain of the amplifying means is controlled by the resistance value of the first and second feedback resistors connected in parallel. This allows the amplifying means to keep linearity without saturating even when the input signal changes from a lower level than the predetermined threshold to a higher level than the predetermined threshold.
- Here, when an input signal having a higher level than the predetermined threshold is supplied, the phase compensation capacitor is charged under the control of the second switching means for phase compensation of the amplifying means. However, even when the input signal has a lower level than the predetermined threshold, the phase compensation capacitor is charged at predetermined timing under the control of third switching means, preventing a high current from being pulled into the amplifying means when the input signal changes from a lower level than the predetermined threshold to a higher level than the predetermined threshold, thus reducing noise applied to the output signal.
- The above and other objects, features, and advantages of the present invention will become apparent from the following description based on the accompanying drawings which illustrate examples of preferred embodiments of the present invention.
- FIG. 1 is a circuit diagram showing a configuration example of a conventional preamplification circuit;
- FIG. 2 is a timing chart to explain an operation of the preamplification circuit shown in FIG. 1;
- FIG. 3 is a circuit diagram showing a first embodiment of the preamplification circuit of the present invention;
- FIG. 4 is a timing chart to explain an operation of the preamplification circuit shown in FIG. 3; and
- FIG. 5 is a circuit diagram showing a second embodiment of the preamplification circuit of the present invention.
- (First Embodiment)
- As shown in FIG. 3, this embodiment comprises
inverse amplifier 1 for amplifying and outputting a preamp input signal,buffer circuit 2 for buffering and outputting the signal outputted frominverse amplifier 1, first andsecond feedback resistors inverse amplifier 1 and the output terminal ofbuffer circuit 2 for changing the gain ofinverse amplifier 1,phase compensation capacitor 7 connected between the input terminal and output terminal ofinverse amplifier 1 for compensating the phase ofinverse amplifier 1,FET switch 5 as first switching means for switching the connection between thefeedback resistor 4 andinverse amplifier 1,buffer circuit 2 based on a gain switching signal supplied,FET switch 6 as second switching means for switching between charge/discharge ofphase compensation capacitor 7 based on the gain switching signal or a reset signal and anOR gate 8 as third switching means, whose input terminal is supplied the gain switching signal and the reset signal and output terminal is connected to the gate ofFET switch 6. A signal outputted frombuffer circuit 2 is outputted as a preamp output signal. The resistance values offeedback resistors - The operation of the preamplification circuit in the above configuration will be explained with reference to FIG. 4.
- When a preamp input signal having a lower level than a predetermined threshold is supplied, the gain switching signal is fixed to LOW, which keeps
OFF FET switch 5. As a result,feedback resistor 3 is the only feedback resistor to control the gain ofinverse amplifier 1 and the signal amplified with this gain is outputted as a preamp output signal. - Here, when the preamp input signal is supplied, the reset signal becomes HIGH for every data supplied and then the data is supplied.
- For this reason, even when the gain switching signal is LOW, the HIGH level of the reset signal is transmitted to the gate of
FET switch 6 via ORgate 8 andFET switch 6 turns ON every time the reset signal becomes HIGH. - This causes
phase compensation capacitor 7 to be charged every time the preamp input signal is supplied even when the gain switching signal is LOW, which means that the amount of discharge ofphase compensation capacitor 7 will no longer increase. - Then, when the preamp input signal has a higher level than the predetermined threshold, the gain switching signal becomes HIGH, which turns ON
FET switch 5. Thus, the gain ofinverse amplifier 1 is controlled byfeedback resistors inverse amplifier 1 becomes smaller than when the preamp input signal has a lower level than the predetermined threshold. As a result,inverse amplifier 1 keeps linearity without saturating. - Furthermore, the HIGH level of the gain switching signal is transmitted to the gate of
FET switch 6 via ORgate 8, which turns ONFET switch 6 causingphase compensation capacitor 7 to be charged. This allows the phase ofinverse amplifier 1 to be compensated. Here, even when the gain switching signal is LOW,phase compensation capacitor 7 is charged by the HIGH level of the reset signal every time the preamp input signal is supplied, preventing any high current from being pulled intoinverse amplifier 1 and preventing noise from applying to the preamp output signal. - In this embodiment,
FET switches - (Second Embodiment)
- As shown in FIG. 5, this embodiment comprises
inverse amplifier 1 for amplifying and outputting a preamp input signal,buffer circuit 2 for buffering and outputting the signal outputted frominverse amplifier 1, first andsecond feedback resistors inverse amplifier 1 and the output terminal ofbuffer circuit 2 for changing the gain ofinverse amplifier 1,phase compensation capacitor 7 connected between the input terminal and output terminal ofinverse amplifier 1 for compensating the phase ofinverse amplifier 1,FET switch 5 as first switching means for switching the connection between thefeedback resistor 4 andinverse amplifier 1,buffer circuit 2 based on a gain switching signal supplied,FET switch 6 as second switching means for switching between charge/discharge ofphase compensation capacitor 7 based on the gain switching signal and anFET switch 9 as third switching means for switching between charge/discharge ofphase compensation capacitor 7 based on a reset signal that becomes HIGH every time a preamp input signal is supplied. A signal outputted frombuffer circuit 2 is outputted as a preamp output signal. The resistance values offeedback resistors - The operation of the preamplification circuit in the above configuration will be explained below.
- When a preamp input signal having a lower level than a predetermined threshold is supplied, the gain switching signal is fixed to LOW, which keeps
OFF FET switch 5. As a result,feedback resistor 3 is the only feedback resistor to control the gain ofinverse amplifier 1 and the signal amplified with this gain is outputted as a preamp output signal. - Here, when the preamp input signal is supplied, the reset signal becomes HIGH for every data supplied and then the data is supplied.
- For this reason, even when the gain switching signal is LOW, the HIGH level of the reset signal is transmitted to the gate of
FET switch 9 andFET switch 9 turns ON every time the reset signal becomes HIGH. - This causes
phase compensation capacitor 7 to be charged every time the preamp input signal is supplied even when the gain switching signal is LOW, which means that the amount of discharge ofphase compensation capacitor 7 will no longer increase. - Then, when the preamp input signal has a higher level than the predetermined threshold, the gain switching signal becomes HIGH, which turns ON
FET switch 5. Thus, the gain ofinverse amplifier 1 is controlled byfeedback resistors inverse amplifier 1 becomes smaller than when the preamp input signal has a lower level than the predetermined threshold. As a result,inverse amplifier 1 keeps linearity without saturating. - Furthermore, the HIGH level of the gain switching signal is transmitted to the gate of
FET switch 6, which turns ONFET switch 6 causingphase compensation capacitor 7 to be charged. This allows the phase ofinverse amplifier 1 to be compensated. Here, even when the gain switching signal is LOW,phase compensation capacitor 7 is charged by the HIGH level of the reset signal every time the preamp input signal is supplied, preventing any high current from being pulled intoinverse amplifier 1 and preventing noise from applying to the preamp output signal. - In this embodiment, FET switches5, 6 and 9 are used as the first to third switching means, but the present invention is not limited to this and other switches can also be used.
- While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the sprit or scope of the following claims.
Claims (14)
Applications Claiming Priority (2)
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JP2000-140140 | 2000-05-12 | ||
JP2000140140A JP2001320253A (en) | 2000-05-12 | 2000-05-12 | Preamplifier circuit |
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US20020017951A1 true US20020017951A1 (en) | 2002-02-14 |
US6404282B2 US6404282B2 (en) | 2002-06-11 |
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US09/852,738 Expired - Fee Related US6404282B2 (en) | 2000-05-12 | 2001-05-11 | Preamplification circuit |
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JP (1) | JP2001320253A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2003774A1 (en) * | 2007-06-15 | 2008-12-17 | Honeywell International Inc. | Variable gain constant bandwidth trans-impedance amplifier for fiber optic rate sensor |
US20090238581A1 (en) * | 2008-03-24 | 2009-09-24 | Hitachi, Ltd. | Optical signal receiving circuit |
CN109195067A (en) * | 2018-07-20 | 2019-01-11 | 广州市欧智智能科技有限公司 | A kind of muting control circuit |
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DE102004063229B4 (en) * | 2004-12-22 | 2007-06-14 | Hauni Maschinenbau Ag | Measuring device and method for detecting foreign bodies in a product, in particular in tobacco, cotton or another fiber product |
US7317351B2 (en) * | 2005-08-16 | 2008-01-08 | Intel Corporation | Low noise amplifier |
JP2007305272A (en) * | 2006-05-15 | 2007-11-22 | Sony Corp | Optical pickup device and optical disk device |
US7791222B2 (en) | 2007-06-15 | 2010-09-07 | Samsung Electronics Co., Ltd. | Multi-output power supply device |
KR20130077432A (en) * | 2011-12-29 | 2013-07-09 | 한국전자통신연구원 | Automatic gain control feedback amplifier |
KR20140089052A (en) * | 2013-01-02 | 2014-07-14 | 한국전자통신연구원 | Feedback amplifier |
US9397658B2 (en) * | 2014-06-25 | 2016-07-19 | Freescale Semiconductor, Inc. | Gate drive circuit and a method for controlling a power transistor |
CN111193476B (en) * | 2020-02-27 | 2022-10-14 | 广州慧智微电子股份有限公司 | Amplifier and amplifying method |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS6085613A (en) | 1983-10-17 | 1985-05-15 | Hitachi Ltd | Preamplifier |
JPH02289904A (en) | 1989-04-28 | 1990-11-29 | Nec Corp | Reading out circuit |
JPH08102716A (en) | 1994-09-30 | 1996-04-16 | Hitachi Ltd | Burst optical reception circuit |
JPH098563A (en) | 1995-06-20 | 1997-01-10 | Nec Miyagi Ltd | Light receiving preamplifier |
JP2737718B2 (en) | 1995-09-29 | 1998-04-08 | 日本電気株式会社 | Optical receiving circuit |
JP3059104B2 (en) | 1996-06-25 | 2000-07-04 | 三菱電機株式会社 | Negative feedback preamplifier |
JPH11340745A (en) * | 1998-05-28 | 1999-12-10 | Nec Corp | Trans impedance type amplifier circuit |
US6114910A (en) * | 1998-12-14 | 2000-09-05 | Raytheon Company | Temperature compensated amplifier and operating method |
JP2001217657A (en) * | 2000-02-01 | 2001-08-10 | Oki Electric Ind Co Ltd | Preamplifier for optical communication |
US6246284B1 (en) * | 2000-02-15 | 2001-06-12 | Oki Electric Industry Co., Ltd. | Negative feedback amplifier with automatic gain control function |
JP3786556B2 (en) * | 2000-02-23 | 2006-06-14 | シャープ株式会社 | Receiver amplifier circuit |
-
2000
- 2000-05-12 JP JP2000140140A patent/JP2001320253A/en active Pending
-
2001
- 2001-05-11 US US09/852,738 patent/US6404282B2/en not_active Expired - Fee Related
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2003774A1 (en) * | 2007-06-15 | 2008-12-17 | Honeywell International Inc. | Variable gain constant bandwidth trans-impedance amplifier for fiber optic rate sensor |
US20090238581A1 (en) * | 2008-03-24 | 2009-09-24 | Hitachi, Ltd. | Optical signal receiving circuit |
US8170425B2 (en) | 2008-03-24 | 2012-05-01 | Hitachi, Ltd. | Optical signal receiving circuit |
CN109195067A (en) * | 2018-07-20 | 2019-01-11 | 广州市欧智智能科技有限公司 | A kind of muting control circuit |
Also Published As
Publication number | Publication date |
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JP2001320253A (en) | 2001-11-16 |
US6404282B2 (en) | 2002-06-11 |
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