Patent US5363064A successfully refreshed from Google Patents.
US5363064A
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US
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Preamplifier for optical communication having a gain control circuit
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1993-04-22
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Granted: 1994-11-08
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Expires: 2013-04-22
Abstract
Abstract A phase-inverting amplifier includes an input-stage FET, a load thereof and a gain control circuit. The gain control circuit is provided in parallel with the load, and reduces an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a predetermined value. The gain control circuit is typically a FET whose gate is biased at a constant voltage. A feedback resistor is provided in a negative feedback path of the phase-inverting amplifier. A bypass circuit is provided in parallel with the feedback resistor, and reduces an effective feedback resistance when a feedback quantity exceeds a predetermined value.
Inventors
- 👤 Yasuki Mikamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:45
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/34; H03F1/342; H03F3/00; H03F3/04; H03F3/08; H03F3/082; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3084
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
121 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for increasing a bandwidth for the preamplifier so that the preamplifier bandwidth remains wider than a bandwidth of an optical receiver which includes the preamplifier, the increase being achieved by reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value.
Claim 2
Dependent Claim
121 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for increasing a bandwidth for the preamplifier so that the preamplifier bandwidth remains wider than a bandwidth of an optical receiver which includes the preamplifier, the increase being achieved by reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value.
Claim 3
Dependent Claim
44 words
The preamplifier of claim 1, wherein the gain control means comprises a gain-control FET, a source and a drain of the gain-control FET being connected to respective terminals of the load, and a gate of the gain-control FET being biased at a constant voltage.
Claim 4
Dependent Claim
19 words
The preamplifier of claim 1, wherein the gain control means comprises a diode provided in parallel with the load.
Claim 5
Dependent Claim
21 words
The preamplifier of claim 1, wherein the bypass means comprises a diode which is provided in parallel with the feedback resistor.
Claim 6
Dependent Claim
136 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for reducing an effective load and resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises an enhancement-type FET, a drain and a gate of the enhancement-type FET being connected to one terminal of the feedback resistor and a source of the enhancement-type FET being connected to the other terminal of the feedback resistor.
Claim 7
Dependent Claim
136 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for reducing an effective load and resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises an enhancement-type FET, a drain and a gate of the enhancement-type FET being connected to one terminal of the feedback resistor and a source of the enhancement-type FET being connected to the other terminal of the feedback resistor.
Claim 8
Dependent Claim
131 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises a depletion-type FET, a drain and a source of the depletion-type FET being connected to respective terminals of the feedback resistor, and a gate of the depletion-type FET being biased at a constant voltage.
Claim 9
Dependent Claim
131 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises a depletion-type FET, a drain and a source of the depletion-type FET being connected to respective terminals of the feedback resistor, and a gate of the depletion-type FET being biased at a constant voltage.
Claim 10
Dependent Claim
135 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises a depletion-type FET, a drain and a source of the depletion-type FET being connected to respective terminals of the feedback resistor, and a gate of the depletion-type FET being controlled by an output signal of the phase-inverting amplifier.
Claim 11
Dependent Claim
135 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; gain control means for reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises a depletion-type FET, a drain and a source of the depletion-type FET being connected to respective terminals of the feedback resistor, and a gate of the depletion-type FET being controlled by an output signal of the phase-inverting amplifier.
Claim 12
Dependent Claim
149 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; voltage dividing means for dividing an output signal of the phase-inverting amplifier; gain control means for reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the, phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises a depletion-type FET, a drain and a source of the depletion-type FET being connected to respective terminals of the feedback resistor, and a gate of the depletion-type FET being controlled by the divided output signal of the voltage dividing means.
Claim 13
Dependent Claim
149 words
A preamplifier for optical communication that amplifies an input signal produced by a photodetector, comprising: a phase-inverting amplifier including an input-state FET and a load thereof, for amplifying the input signal; voltage dividing means for dividing an output signal of the phase-inverting amplifier; gain control means for reducing an effective load resistance to lower an open-loop gain of the phase-inverting amplifier when a current flowing through the load exceeds a first predetermined value; a feedback resistor provided in a negative feedback path of the, phase-inverting amplifier; and bypass means for reducing an effective feedback resistance when a feedback quantity exceeds a second predetermined value, wherein the bypass means comprises a depletion-type FET, a drain and a source of the depletion-type FET being connected to respective terminals of the feedback resistor, and a gate of the depletion-type FET being controlled by the divided output signal of the voltage dividing means.
Claim 14
Dependent Claim
26 words
The preamplifier of claim 8, wherein the voltage dividing means comprises a FET for source-following the output signal, and resistors for dividing the source-followered output signal.
Claim 15
Dependent Claim
55 words
The preamplifier of claim 8, wherein the voltage dividing means comprises a FET for source-following the output signal, and a second depletion-type FET, a gate and a source of the second depletion-type FET being connected to each other and a drain of the second depletion-type FET being connected to a source of the source-following FET.
Claim 16
Dependent Claim
52 words
The preamplifier of claim 9, wherein the voltage dividing means comprises a second depletion-type FET provided in parallel with one of the resistors, a gate and a source of the second depletion-type FET being connected to each other, and the divided output signal appearing at a drain of the second depletion-type FET.
Claim 17
Dependent Claim
19 words
The preamplifier of claim 1, wherein FETs used in the phase-inverting amplifier and the bypass means are GaAs MESFETs.
References Cited (Backward Citations)
US4218613A
Cited
US4620321A
Cited
US4623786A
Cited
US4808810A
Cited
EP0382373A2
Cited
US5025226A
Cited
US5030925A
Cited
US5216386A
Cited
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| 3.5 Years (Year 4) | 1997-11-07 | 1998-05-09 | 1998-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-07 | 2002-05-09 | 2002-11-08 | $3760.00 | Window Closed / Lapsed |
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