DE3340034A1 - Bipolar analog switch - Google Patents
Bipolar analog switchInfo
- Publication number
- DE3340034A1 DE3340034A1 DE19833340034 DE3340034A DE3340034A1 DE 3340034 A1 DE3340034 A1 DE 3340034A1 DE 19833340034 DE19833340034 DE 19833340034 DE 3340034 A DE3340034 A DE 3340034A DE 3340034 A1 DE3340034 A1 DE 3340034A1
- Authority
- DE
- Germany
- Prior art keywords
- current
- switching transistor
- analog switch
- supplied
- emitter
- 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.)
- Ceased
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/16—Modifications for eliminating interference voltages or currents
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/60—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors
Abstract
Description
Bipolarer Analogschalter Bipolar analog switch
Ein bipolarer Analogschalter besteht bekanntlich aus einem Schalter, einer Stromquelle und einem Schalttransistor. Der Schalter hat die Aufgabe, die Stromquelle zu aktivieren, während die Stromquelle den Schalttransistor ansteuert.As is well known, a bipolar analog switch consists of a switch, a current source and a switching transistor. The switch does the job that Activate current source, while the current source controls the switching transistor.
Der Erfindung liegt die Erkenntnis zugrunde, daß bei den bekannten bipolaren Analogschaltern das vom Schalttransistor durchzuschaltende Signal durch den von der Stromquelle gelieferten Steuerstrom verfälscht ist.The invention is based on the knowledge that in the known bipolar analog switches through the signal to be switched through by the switching transistor the control current supplied by the power source is corrupted.
Eine solche Verfälschung tritt z. B. bei C-MOS-Analogschaltern nicht auf.Such a falsification occurs z. B. not with C-MOS analog switches on.
Der Erfindung liegt die Aufgabe zugrunde, einen bipolaren Analogschalter anzugeben, der eine möglichst geringe Signalverfälschung aufweist. Diese Aufgabe wird bei einem bipolaren Analogschalter mit einem Schalttransistor, dessen Basis ein Steuerstrom zugeführt wird, nach der Erfindung dadurch gelöst, daß der Emitter-Basisstrom des Schalttransistors durch einen Strom kompensiert wird, der dem Emitter des Schalttransistors zugeführt wird.The invention is based on the object of a bipolar analog switch indicate that has the lowest possible signal corruption. This task is the base of a bipolar analog switch with a switching transistor a control current is supplied, achieved according to the invention in that the emitter base current of the switching transistor is compensated by a current flowing to the emitter of the switching transistor is fed.
Durch die Kompensation des Emitter-Basisstromes des Schalttransistors wird die Verfälschung aufgehoben, die der Signalstrom (Emitter-Kollektorstrom) des Schalttransistors ohne die nach der Erfindung vorgesehenen Kompensationsmittel erfährt. Der Kompensationsstrom wird beispielsweise durch eine Stromteilerschaltung erzeugt, die einen von einer Stromquelle gelieferten Strom in zwei möglichst gleiche Stromteile aufteilt, sowie durch eine Schaltung, die die Richtung des einen Stromteils umkehrt. Die Umkehr der Stromrichtung bewirkt beispielsweise eine Stromspiegelschaltung.By compensating for the emitter base current of the switching transistor the falsification of the signal current (emitter-collector current) of the Experiences switching transistor without the compensation means provided according to the invention. The compensation current is generated, for example, by a current divider circuit, the one current supplied by a current source into two current parts that are as similar as possible divides, as well as by a circuit that reverses the direction of the current part. The reversal of the current direction effects a current mirror circuit, for example.
Die Erfindung wird im folgenden an einem Ausführungsbeispiel erläutert.The invention is explained below using an exemplary embodiment.
Die Figur 1 zeigt einen bipolaren Analogschalter nach der Erfindung. Der Analogschalter der Figur 1 weist eine Stromquelle Q auf, die von einem Schalter S geschaltet wird. Der von der Stromquelle Q gelieferte, geschaltete Strom IQ1 wird einer aus den Transistoren T1 und T?' bestehenden Stromteilerschaltung zugeführt, die die Aufgabe hat, den Strom IQ1 in zwei möglichst gleiche Teile aufzuteilen und damit zwei gleich große Ströme zu liefern, von denen der eine (I1) der Basis des Schalttransistors T3 und der andere (IK1) ) einer Stromspiegelschaltung zugeführt wird, die im Ausführungsbeispiel aus den Transistoren T2, T4 und T5 besteht und die Eigenschaft hat, daß sie den Strom (IK1), ), der ihr zugeführt wird, in seiner Richtung umkehrt. Der Transistor T4 liefert also einen Strom 12, der entgegengesetzt gleich dem Steuerstrom I1 für den Schalttransistor ist. Wird der vom Transistor T4 gelieferte Strom I2 gemäß dem Ausführungsbeispiel der Figur 1 dem Emitter des Schalttransistors T3 zugeführt, so kompensiert er den Emitter-Basisstrom des Schalttransistors T3 und damit die Verfälschung des Signalstromes des Schalttransistors T3 durch dessen Emitter-Basisstrom. Der Steuerstrom I1 hat also infolge der Kompensation keinen negativen Einfluß mehr auf den Strom des Signalpfades des Transistors T3.FIG. 1 shows a bipolar analog switch according to the invention. The analog switch of Figure 1 has a current source Q, which is from a switch S is switched. The switched current IQ1 supplied by the current source Q is one of the transistors T1 and T? ' existing current divider circuit supplied, which has the task of dividing the current IQ1 into two parts that are as equal as possible and thus delivering two currents of equal size, one of which (I1) is the base of the Switching transistor T3 and the other (IK1)) fed to a current mirror circuit which in the exemplary embodiment consists of transistors T2, T4 and T5 and has the property that it contains the current (IK1),) which is fed to it Direction reverses. The transistor T4 thus supplies a current I2, which is the opposite is equal to the control current I1 for the switching transistor. Will the transistor T4 supplied current I2 according to the embodiment of Figure 1 to the emitter of Switching transistor T3 supplied, in this way it compensates for the emitter base current of the switching transistor T3 and thus the falsification of the signal current of the switching transistor T3 through its emitter base current. The control current I1 therefore has as a result of the compensation no more negative influence on the current of the signal path of the transistor T3.
Wird der Schalter S eingeschaltet, so liefert die Stromquelle Q mit Einschalten des Schalters S einen Steuerstrom IQ1 an den Emitter des Transistors T1 und schaltet den Signalpfad über den Transistor T3 ein. Die aus den Transistoren T1 und T1' bestehende Stromteilerschaltung teilt den Strom IQ1, wie bereits erwähnt, in zwei möglichst gleiche Teile. Die Stromteilung mittels der Stromspiegelschaltung T1>11 erfolgt aufgrund folgender Beziehungen: I1 = IK2 + IB1 ' IB1' = 1Q1/B1 .B1 << IK2 I1# K2 IK1 = IK2 Die durch den Basisstrom I1 verursachte Signalverfälschung des Signalstroms durch den Transistor T3 wird, wie bereits erwähnt, dadurch verhindert, daß der über die Stromspiegelschaltung T2,4,5 gespiegelte Strom IK1, der annähernd gleich I1 ist, als Strom I2 den Basisstrom I1 wegen der Beziehung I2 = - Ii kompensiert.If the switch S is switched on, the current source Q also supplies Switching on the switch S sends a control current IQ1 to the emitter of the transistor T1 and switches on the signal path via transistor T3. The ones from the transistors T1 and T1 'existing current divider circuit divides the current IQ1, as already mentioned, into two parts that are as equal as possible. The current division by means of the current mirror circuit T1> 11 occurs due to the following relationships: I1 = IK2 + IB1 'IB1' = 1Q1 / B1 .B1 << IK2 I1 # K2 IK1 = IK2 The signal corruption caused by the base current I1 the signal current through the transistor T3 is, as already mentioned, prevented by that the current IK1 mirrored via the current mirror circuit T2,4,5, which is approximately is equal to I1, as current I2 compensates for the base current I1 because of the relationship I2 = - Ii.
In einer weiteren Ausführungsform nach Fig. 2 wird der nutzbare Signalhub um eine Flußspannung erhöht und die UcE-Abhängigkeit der Kollektorströme im Stromteiler ausgeschaltet.In a further embodiment according to FIG. 2, the usable signal swing increased by a forward voltage and the UcE dependence of the collector currents in the current divider switched off.
Die UCE-Abhängigkeit der Kollektorströme 1K3 und IK4 wird relativ zueinander vollkommen kompensiert, weil durch S bzw. UBE T7 beide Kollektoren auf gleichem Potential gehalten werden.The UCE dependence of the collector currents 1K3 and IK4 becomes relative Completely compensated for each other because both collectors are open by S or UBE T7 must be kept at the same potential.
1K3 dient wieder als Steuerstrom für den Schalttransistor T3 (IB7 << « IK3). T7 dient als Emitterfolger für das Basispotential von T3. T8 erhält über T7 genau soviel Basisstrom angeboten, um IK4 - IK4 - IK4 am Kollektor übernehmen zu können. B8 B8-B71K3 is used again as a control current for the switching transistor T3 (IB7 << «IK3). T7 serves as an emitter follower for the base potential of T3. T8 receives Exactly as much base current is offered via T7 to take over IK4 - IK4 - IK4 at the collector to be able to. B8 B8-B7
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833340034 DE3340034A1 (en) | 1983-11-05 | 1983-11-05 | Bipolar analog switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833340034 DE3340034A1 (en) | 1983-11-05 | 1983-11-05 | Bipolar analog switch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DE3340034A1 true DE3340034A1 (en) | 1985-05-23 |
Family
ID=6213538
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DE19833340034 Ceased DE3340034A1 (en) | 1983-11-05 | 1983-11-05 | Bipolar analog switch |
Country Status (1)
| Country | Link |
|---|---|
| DE (1) | DE3340034A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4443469A1 (en) * | 1994-12-07 | 1996-06-27 | Telefunken Microelectron | Bipolar transistor circuit including base current compensation mirror |
| US8250924B2 (en) | 2008-04-22 | 2012-08-28 | Rosemount Inc. | Industrial process device utilizing piezoelectric transducer |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2524642A1 (en) * | 1974-06-04 | 1976-02-05 | North Electric Co | DRIVER ARRANGEMENT FOR A SWITCHING TRANSISTOR |
| DE2655173B2 (en) * | 1976-12-06 | 1979-05-17 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Switching device with at least one transistor |
| DE2851410A1 (en) * | 1977-11-30 | 1979-06-07 | Hitachi Ltd | ELECTRONIC SWITCHING DEVICE |
-
1983
- 1983-11-05 DE DE19833340034 patent/DE3340034A1/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2524642A1 (en) * | 1974-06-04 | 1976-02-05 | North Electric Co | DRIVER ARRANGEMENT FOR A SWITCHING TRANSISTOR |
| DE2655173B2 (en) * | 1976-12-06 | 1979-05-17 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Switching device with at least one transistor |
| DE2851410A1 (en) * | 1977-11-30 | 1979-06-07 | Hitachi Ltd | ELECTRONIC SWITCHING DEVICE |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4443469A1 (en) * | 1994-12-07 | 1996-06-27 | Telefunken Microelectron | Bipolar transistor circuit including base current compensation mirror |
| US8250924B2 (en) | 2008-04-22 | 2012-08-28 | Rosemount Inc. | Industrial process device utilizing piezoelectric transducer |
| US9921120B2 (en) | 2008-04-22 | 2018-03-20 | Rosemount Inc. | Industrial process device utilizing piezoelectric transducer |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| OM8 | Search report available as to paragraph 43 lit. 1 sentence 1 patent law | ||
| OP8 | Request for examination as to paragraph 44 patent law | ||
| 8131 | Rejection |