Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1982-08-18
1985-05-28
Miller, Stanley D.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
307571, 307317R, H03K 1774, H03K 1760, H03K 1921
Patent
active
045202788
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an electronic switch for switching electrical signals, comprising an input buffer of the open collector type of which the input is connected to the control input of the switch and of which the output is connected to (1) the input of an output buffer of which the output is connected to the signal input of the switch, (2) a diode of which the other electrode is connected to the signal input of said switch and (3) a load resistance.
Such a switch is already known from the Ducth Patent Application No. 75.11022. In said known switch one terminal of load resistance, of which the other terminal is connected to the output of the input buffer, is connected to one power supply terminal. The switch is controlled by a signal onto the control input having a potential equal to the potential of said one power supply terminal, or equal to the potential at the other power supply terminal.
FIG. 1 shows a schematic diagram of such a known switch. Said switch comprises the input buffer 1, of which the input is connected to the control input 2 of the switch. The output of said buffer 1 is connected to the base of the output transistor 3, to the one electrode of the diode 4 and to a terminal of the resistance 5. The other electrode of said diode 4 is connected to the signal input 6 and the other terminal of the resistance 5 is connected to the power supply terminal 7. The collector of the transistor 3 is also connected to said power supply terminal 7 and the emitter of said transistor is connected to the signal output of the switch and through the resistor 9 also connected to the other power supply terminal 10, which in this case is earthed. Said switch is controlled by a signal onto the control input 2 which signal may be switched between two levels equal to the one or the other power supply voltage level. The signals onto the signal input 6 are varying between said power supply levels. When the control input 2 is earthed, then also the output of the buffer 1 will be earthed, so that the diode is not conducting and it is not possible to transfer signals from the input 6 to the output 8. Also transistor 1 is not conducting. Because the output level of buffer 1 is approximately equal to the earth level a current is running through the resistance 5 and the output stage of the buffer 1. If a voltage practically equal to the power supply voltage +V is supplied to the control input 2, then the output of the buffer 1 will, because of the resistance 5, reach a level higher than the earth potential, so that diode 4 is conducting. Also transistor 3 comes into the conducting state because of said higher potential level and in this situation it is possible to transfer signals from the input 6 to the output 8. In this case a current is running through the transistor 3 and the load resistance 9 and through the resistance 5 and the diode 4. In a practical embodiment of this circuit it is not inconceivable that the "open" switch draws more current than the "closed" switch. Especially when such a switch is used into an array having a number of switches of equal type, whereby every time only one of said switches is closed, the fact that the open switches are drawing a relatively heavy current is a serious disadvantage.
The object of the invention is now to significantly reduce the current through the open switch.
According to the invention said object is reached in that the other terminal of the load resistance is connected to the signal input of the switch.
The result thereof is that, let alone eventual leakage currents, there is no current through the open switch.
The invention will be explained in detail with reference to an embodiment by way of example illustrated in the figures.
FIG. 1, which is already discussed, shows a prior art switch.
FIG. 2 illustrates a switch according to the invention.
The components used in the switch illustrated in FIG. 2 are indicated by the same reference numbers as the components in FIG. 1. It appears from a comparison between FIGS. 1 and 2 that only the resistance 5 is connected into
REFERENCES:
patent: 4000428 (1976-12-01), Harshbarger
patent: 4119869 (1978-10-01), Hashimoto
Davis B. P.
Deltakabel B.V.
Miller Stanley D.
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