Patent US3801748A successfully refreshed from Google Patents.
US3801748A
Expired / Lapsed
US
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High speed signal multiplexer
Assignee: Harris Corp
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Filing: 1972-09-20
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Granted: 1974-04-02
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Expires: 1992-09-20
Abstract
Abstract An analog signal multiplexer uses constant-current devices to multiplex accurately at a high sampling rate. The multiplexer sequentially connects signals from a plurality of input channels to an output bus. Each input signal is passed through an amplifier and then connected through a diode switching circuit to the output bus. Each diode switching circuit comprises two diodes opposingly connected in series, with their junction also connected to a constant-current sink which can be turned on and off by a command pulse. A constant-current source, used in succession by all of the input channels, continuously provides current directly to the common output bus, of an amount one-half as great as is drawn by each constant-current sink. A channel is selected by turning on its current sink, whereupon both diodes of the selected channel conduct and the voltage at the selected amplifier is reproduced at the output bus. Each amplifier supplies current to a constant-current sink substitute load when the channel is not selected.
Inventors
- 👤 W Cotten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:46
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/04; H04J3/047
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
343 words
A multiplexer for selectively connecting one of a plurality of available signals to an output of the multiplexer in accordance with selection signals, comprising a plurality of switchable input channels each having an output terminal, all of said output terminals being connected together to serve as the multiplexer output, means for providing a first constant current having a first current polarity to said output terminals, said first constant-current being regulated by amplification in response to deviations of the first current from a predetermined value, and selection means providing control signals to said switchable input channels for selecting one channel and blocking the other channels, wherein each of said switchable input channels further comprises a signal terminal having a signal voltage responsive to one of said available signals, a first rectifying means connected to said signal terminal and having a second electrode for, upon selection of that channel, transferring from the signal terminal to the second electrode the signal voltage diminished by a current-dependent voltage drop in the first rectifying means, a second rectifying means opposably connected to the second electrode of the first rectifying means for, upon selection of that channel, transferring from said second electrode to said output terminal the signal voltage diminished by the voltage drop in the First rectifying means and augmented by a current-dependent voltage drop in the second rectifying means, and means for providing a total constant current having a current polarity opposite said first current polarity, said total constant current being regulated by amplification in response to deviations of the total current from a second predetermined value and being switchably responsive to said control signals for, upon selection of the channel, drawing the total constant current from said first and second rectifying means collectively to enable transfers of signals through said first and second rectifying means, said total current being such that the magnitude of said voltage drop in the first rectifying means equals the magnitude of said voltage drop in the second rectifying means, whereby a voltage at the multiplexer output tracks the selected signal voltage.
Claim 2
Dependent Claim
343 words
A multiplexer for selectively connecting one of a plurality of available signals to an output of the multiplexer in accordance with selection signals, comprising a plurality of switchable input channels each having an output terminal, all of said output terminals being connected together to serve as the multiplexer output, means for providing a first constant current having a first current polarity to said output terminals, said first constant-current being regulated by amplification in response to deviations of the first current from a predetermined value, and selection means providing control signals to said switchable input channels for selecting one channel and blocking the other channels, wherein each of said switchable input channels further comprises a signal terminal having a signal voltage responsive to one of said available signals, a first rectifying means connected to said signal terminal and having a second electrode for, upon selection of that channel, transferring from the signal terminal to the second electrode the signal voltage diminished by a current-dependent voltage drop in the first rectifying means, a second rectifying means opposably connected to the second electrode of the first rectifying means for, upon selection of that channel, transferring from said second electrode to said output terminal the signal voltage diminished by the voltage drop in the First rectifying means and augmented by a current-dependent voltage drop in the second rectifying means, and means for providing a total constant current having a current polarity opposite said first current polarity, said total constant current being regulated by amplification in response to deviations of the total current from a second predetermined value and being switchably responsive to said control signals for, upon selection of the channel, drawing the total constant current from said first and second rectifying means collectively to enable transfers of signals through said first and second rectifying means, said total current being such that the magnitude of said voltage drop in the first rectifying means equals the magnitude of said voltage drop in the second rectifying means, whereby a voltage at the multiplexer output tracks the selected signal voltage.
Claim 3
Dependent Claim
30 words
A multiplexer as defined in claim 1 wherein said first and second rectifying means have substantially matched current-dependent voltage drops and wherein said total current is twice said first current.
Claim 4
Dependent Claim
90 words
A multiplexer as defined in claim 1 wherein each of said switchable input channels further comprises signal source means for continuously providing a signal current to said signal terminal and wherein each of said switchable input channels further comprises a substitute switchable source of constant current switchably responsive to said control signals for drawing said signal current from said signal terminal only when the channel is not selected, whereby said signal current in a channel is substantially the same when the channel is selected as when it is not selected.
Claim 5
Dependent Claim
93 words
A multiplexer as defined in claim 3 wherein said substitute switchable source comprises a static selector switch connected to said signal terminal and responsive to said control signals, a constant-current generator connected to said static selector switch, and an idling current circuit connected to said static selector switch, and wherein said static selector switch selects said idling current circuit for providing current to said constant-current generator when the corresponding input channel is selected and selects the signal terminal for providing current to the constant-current generator when the corresponding input channel is not selected.
Claim 6
Dependent Claim
72 words
A multiplexer as defined in claim 1 wherein each of said switchable input channels further comprises signal source means having an input terminal receiving one of said available signals for providing to said signal terminal a signal voltage responsive to said one of said available signals, said signal source means having offsetting means for offsetting said signal voltage by a voltage component whose amount is predetermined and unresponsive to said available signals.
Claim 7
Dependent Claim
105 words
A multiplexer as defined in claim 1 wherein said means for providing a total constant current comprises a static selector switch connected to said second electrode and responsive to said control signals, a constant-current generator connected to said static selector switch, and an idling current circuit connected to said static selector switch, and wherein said static selector switch selects the first and second rectifying means at said second electrode for collectively providing current to said constant-current generator when the corresponding input channel is selected and selects said idling current circuit for providing current to said constant-current generator when the corresponding input channel is not selected.
Claim 8
Dependent Claim
213 words
A multiplexer for selectively connecting one of a plurality of available signals to a common output bus in accordance with selection signals, comprising a plurality of sources of input signals, a first plurality of rectifying means each having a signal terminal and a second terminal and each having its signal terminal connected to a different one of said sources of input signals for conducting current therefrom to said second terminal, a second plurality of rectifying means each having a first termiNal and a second terminal and each having its second terminal connected in a junction to the second terminal of one of said first plurality of rectifying means for conducting current to each of said junctions, a common output bus to which the first terminal of each of said second plurality of rectifying means is connected, a current source connected to said output bus for supplying regulated current to said output bus, and a plurality of regulated current sinks, each being connected to a different one of said junctions and each being switchable to conduction and non-conduction from said junctions in accordance with said selection signals for selectively drawing from one at a time of said junctions a regulated current substantially twice as great as the regulated current supplied by said current source.
Claim 9
Dependent Claim
213 words
A multiplexer for selectively connecting one of a plurality of available signals to a common output bus in accordance with selection signals, comprising a plurality of sources of input signals, a first plurality of rectifying means each having a signal terminal and a second terminal and each having its signal terminal connected to a different one of said sources of input signals for conducting current therefrom to said second terminal, a second plurality of rectifying means each having a first termiNal and a second terminal and each having its second terminal connected in a junction to the second terminal of one of said first plurality of rectifying means for conducting current to each of said junctions, a common output bus to which the first terminal of each of said second plurality of rectifying means is connected, a current source connected to said output bus for supplying regulated current to said output bus, and a plurality of regulated current sinks, each being connected to a different one of said junctions and each being switchable to conduction and non-conduction from said junctions in accordance with said selection signals for selectively drawing from one at a time of said junctions a regulated current substantially twice as great as the regulated current supplied by said current source.
Claim 10
Dependent Claim
109 words
A multiplexer as defined in claim 7 wherein each of said plurality of sources of input signals comprises a voltage source for establishing a voltage signal at said signal terminal of a corresponding one of said first plurality of rectifying means, and a compensating current sink with gain connected to said signal terminal, said compensating current sink being switchable to conduction and non-conduction from said signal terminal in accordance with a logical inverse of said selection signal for drawing from said signal terminal a current substantially equal to the regulated current supplied by said current source when the corresponding one of said plurality of current sinks is not conducting.
Claim 11
Dependent Claim
36 words
A multiplexer as defined in claim 8 wherein the compensating current sink comprises a constant-current generator with gain, and wherein said current drawn from the signal terminal by the conpensating current sink is current-regulated and constant.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |