CA1098185A - Switching device - Google Patents
Switching deviceInfo
- Publication number
- CA1098185A CA1098185A CA305,620A CA305620A CA1098185A CA 1098185 A CA1098185 A CA 1098185A CA 305620 A CA305620 A CA 305620A CA 1098185 A CA1098185 A CA 1098185A
- Authority
- CA
- Canada
- Prior art keywords
- key element
- operational amplifier
- control
- input
- key
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Electronic Switches (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Disclosure is made of a switching device on the basis of an active switching element. The device is built around an operational amplifier whose negative feedback circuit includes serially connected key elements. Control inputs of the key elements are connected to a control bus. Interposed between an inverting input and an output of the operational amplifier is a key element whose control input is connected to the control bus via a single-shot multivibrator and a delay line placed in series therewith.
Disclosure is made of a switching device on the basis of an active switching element. The device is built around an operational amplifier whose negative feedback circuit includes serially connected key elements. Control inputs of the key elements are connected to a control bus. Interposed between an inverting input and an output of the operational amplifier is a key element whose control input is connected to the control bus via a single-shot multivibrator and a delay line placed in series therewith.
Description
~(~981~35 The present invention relates to electric signal commutation equipment and, more particularly, to a switching device.
The device of this invention is applicable, for example, to switching standard resistors of multidigit conductance or resistance boxes.
There is known a switching device which is an active switching element built around an operational amplifier having two key elements placed in series in its negative feedback circuit. When the key elements are energized, the negative feedback circuit of the operational amplifier is closed, and the transition resistance between the input and output terminals of the device is reduced to a small value.
The device under review has a low reliability because when the key elements make or break the circuit, the operational amplifier is not protected from overvoltages in its input circuit. Apart from being the cause of the low reliability of the switching device under review, this disadvantage accounts for a limited sphere of application of switching devices incorporating active switching elements.
It is an object of the present invention to improve the reliability of the switching device.
The proposed design accounts for an improved reliability of the switching device.
In accordance with a preferred embodiment, a switching device on the basis of an active switching element comprises:
a) an operational amplifier having an inverting input, a non-inverting input, and an output' b) a first key element and a second key element connected in series between the output and the inverting input of said operational amplifier so as to comprise a first negative feedback circuit of said operational amplifier, said first and second key elements having control inputs' c) a third key element connected between said output and said inverting input of said operational amplifier so as to comprise a second negative feedback circuit, said third key element having a control input' d) a single-shot multivibrator, e) a delay line con ~cted - la -in series with said single-shot multivibrator, f) a control bus, said control inputs of said first key element and said second key element being connected to said control bus, said control input of said third key element being connected to said control bus via said single-shot multivibrator and said delay line which are connected in series therebetween.
An embodiment of the invention is illustrated in the single Figure herein.
The proposed switching device comprises a switching element built around an operational amplifier 1. The device : . ~, ~:
- : : : .: :
.:`' : :' ` . -~98~5 further includes a single-shot multivibrator 2 and a delay line 3. 'lihe operational amplifier 1 has two negative ~eed-back circuits. ~l~he Yirst circuit is ~ormed with ~he aid o~
a ~ey element 4, whereas the second negative ~eedback cir-cuit is ~ormed with the aid o~ key elements 5 and 6. An in-put terminal 7 o~ the switching de~ice is the point o~ con-ne¢tion o~ the key elements 5 and 6. An output terminal 8 of the switching device is the point of connection of a non-inverting input 9 of the operational amplifier l and a cen-tral tap lO of power sources ll and 12. hn inverting input 13 of the operational amplifier 1 is connected ~ia the key element 4 to an output 14 of the operational amplifier 1, and via the key element 6 to the input terminal 7. The out-put 14 of the operational amplifier l is co~nected via the key element 5 to the input terminal 7. Control inputs 15 and 16 o~ the ke~ elements 5 and 6 are combined and connected to a control bus 17. ~ control input 18 of the key element 4 is connected via the single-shot multivibrator 2 and the delay line 3 to t~e co~trol bus 17.
~ he proposed switching device operates as follows. In the initial state, the key element 4 is closed, and the po-tential at the inverting input 13 o~ the operational ampli-~ier l is equal to the potential at the ou-tput terminal 8 of the switching device. By a signal arriving from a control unit (not shown3~ the key elements 5 and 6 are elosed. The key element 4 is controlled by a signal ~ormed bythe signle-shot multivibrator 2 and delayed by the delay line 3; this signal 1~9~
arrives from the control bus 17. In the course of the tran-sient process due to the closure o~ the key elements 5 and 6, the key element 4 remains closed. ~he key element 4 opens after the delay time which is determined by the dalay line and is either equal to or somewhat longer than the duration of the tra~sient process. "'he potential at the inverting in-put 13 o~ the operational amplif~er 1 is maintained at a level equal to that of the potential at the output terminal 8; this is due to the negative feedback circuit formed by the closed key elements 5 and 6. r~he key elements 5 and 6 are opened in a similar manner, although the key element 4 is closed some-what earlier than the onset o~ the transient process caused by the opening of the key elements 5 and 6; this period i8 determined by the duration of the signal formed by the single-shot multivibrator 2. r~hus in any operating conditions, the input circuits o~ the operational ampli~er 1 have a potential which is equal to the potential at the output terminal 8, whe-reby the input circuits of the operational ampli~ier 1 are protected from input signal overloads. ~he fact that the key element 4 is closed when the key elements 5 and 6 are opened ma~es it possible to utilize a correction circuit (not shown) of the operational amplifier 1, which accounts for a high operating speed of the proposed switching device.
~, ~
The device of this invention is applicable, for example, to switching standard resistors of multidigit conductance or resistance boxes.
There is known a switching device which is an active switching element built around an operational amplifier having two key elements placed in series in its negative feedback circuit. When the key elements are energized, the negative feedback circuit of the operational amplifier is closed, and the transition resistance between the input and output terminals of the device is reduced to a small value.
The device under review has a low reliability because when the key elements make or break the circuit, the operational amplifier is not protected from overvoltages in its input circuit. Apart from being the cause of the low reliability of the switching device under review, this disadvantage accounts for a limited sphere of application of switching devices incorporating active switching elements.
It is an object of the present invention to improve the reliability of the switching device.
The proposed design accounts for an improved reliability of the switching device.
In accordance with a preferred embodiment, a switching device on the basis of an active switching element comprises:
a) an operational amplifier having an inverting input, a non-inverting input, and an output' b) a first key element and a second key element connected in series between the output and the inverting input of said operational amplifier so as to comprise a first negative feedback circuit of said operational amplifier, said first and second key elements having control inputs' c) a third key element connected between said output and said inverting input of said operational amplifier so as to comprise a second negative feedback circuit, said third key element having a control input' d) a single-shot multivibrator, e) a delay line con ~cted - la -in series with said single-shot multivibrator, f) a control bus, said control inputs of said first key element and said second key element being connected to said control bus, said control input of said third key element being connected to said control bus via said single-shot multivibrator and said delay line which are connected in series therebetween.
An embodiment of the invention is illustrated in the single Figure herein.
The proposed switching device comprises a switching element built around an operational amplifier 1. The device : . ~, ~:
- : : : .: :
.:`' : :' ` . -~98~5 further includes a single-shot multivibrator 2 and a delay line 3. 'lihe operational amplifier 1 has two negative ~eed-back circuits. ~l~he Yirst circuit is ~ormed with ~he aid o~
a ~ey element 4, whereas the second negative ~eedback cir-cuit is ~ormed with the aid o~ key elements 5 and 6. An in-put terminal 7 o~ the switching de~ice is the point o~ con-ne¢tion o~ the key elements 5 and 6. An output terminal 8 of the switching device is the point of connection of a non-inverting input 9 of the operational amplifier l and a cen-tral tap lO of power sources ll and 12. hn inverting input 13 of the operational amplifier 1 is connected ~ia the key element 4 to an output 14 of the operational amplifier 1, and via the key element 6 to the input terminal 7. The out-put 14 of the operational amplifier l is co~nected via the key element 5 to the input terminal 7. Control inputs 15 and 16 o~ the ke~ elements 5 and 6 are combined and connected to a control bus 17. ~ control input 18 of the key element 4 is connected via the single-shot multivibrator 2 and the delay line 3 to t~e co~trol bus 17.
~ he proposed switching device operates as follows. In the initial state, the key element 4 is closed, and the po-tential at the inverting input 13 o~ the operational ampli-~ier l is equal to the potential at the ou-tput terminal 8 of the switching device. By a signal arriving from a control unit (not shown3~ the key elements 5 and 6 are elosed. The key element 4 is controlled by a signal ~ormed bythe signle-shot multivibrator 2 and delayed by the delay line 3; this signal 1~9~
arrives from the control bus 17. In the course of the tran-sient process due to the closure o~ the key elements 5 and 6, the key element 4 remains closed. ~he key element 4 opens after the delay time which is determined by the dalay line and is either equal to or somewhat longer than the duration of the tra~sient process. "'he potential at the inverting in-put 13 o~ the operational amplif~er 1 is maintained at a level equal to that of the potential at the output terminal 8; this is due to the negative feedback circuit formed by the closed key elements 5 and 6. r~he key elements 5 and 6 are opened in a similar manner, although the key element 4 is closed some-what earlier than the onset o~ the transient process caused by the opening of the key elements 5 and 6; this period i8 determined by the duration of the signal formed by the single-shot multivibrator 2. r~hus in any operating conditions, the input circuits o~ the operational ampli~er 1 have a potential which is equal to the potential at the output terminal 8, whe-reby the input circuits of the operational ampli~ier 1 are protected from input signal overloads. ~he fact that the key element 4 is closed when the key elements 5 and 6 are opened ma~es it possible to utilize a correction circuit (not shown) of the operational amplifier 1, which accounts for a high operating speed of the proposed switching device.
~, ~
Claims
1. A switching device on the basis of an active switching element, comprising:
a) an operational amplifier having an inverting input, a non-inverting input, and an output;
b) a first key element and a second key element connected in series between the output and the inverting input of said operational amplifier so as to comprise a first negative feedback circuit of said operational amplifier, said first and second key elements having control inputs;
c) a third key element connected between said output and said inverting input of said operational amplifier so as to comprise a second negative feedback circuit, said third key element having a control input;
d) a single-shot multivibrator;
e) a delay line connected in series with said single-shot multivibrator;
f) a control bus, said control inputs of said first key element and said second key element being connected to said control bus, said control input of said third key element being connected to said control bus via said single-shot multi-vibrator and said delay line which are connected in series therebetween.
a) an operational amplifier having an inverting input, a non-inverting input, and an output;
b) a first key element and a second key element connected in series between the output and the inverting input of said operational amplifier so as to comprise a first negative feedback circuit of said operational amplifier, said first and second key elements having control inputs;
c) a third key element connected between said output and said inverting input of said operational amplifier so as to comprise a second negative feedback circuit, said third key element having a control input;
d) a single-shot multivibrator;
e) a delay line connected in series with said single-shot multivibrator;
f) a control bus, said control inputs of said first key element and said second key element being connected to said control bus, said control input of said third key element being connected to said control bus via said single-shot multi-vibrator and said delay line which are connected in series therebetween.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA305,620A CA1098185A (en) | 1978-06-16 | 1978-06-16 | Switching device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA305,620A CA1098185A (en) | 1978-06-16 | 1978-06-16 | Switching device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1098185A true CA1098185A (en) | 1981-03-24 |
Family
ID=4111707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA305,620A Expired CA1098185A (en) | 1978-06-16 | 1978-06-16 | Switching device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1098185A (en) |
-
1978
- 1978-06-16 CA CA305,620A patent/CA1098185A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |