US3564291A

US3564291A - Electronic relay arrangement

Info

Publication number: US3564291A
Application number: US684240A
Authority: US
Inventors: Einar Andreas Aagaard
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1966-11-30
Filing date: 1967-11-20
Publication date: 1971-02-16
Anticipated expiration: 1988-02-16
Also published as: DK119413B; CH496369A; JPS4828468B1; SE326730B; DE1286098B; GB1213636A; AT284250B; BE707216A; NL6616834A

Abstract

An electronic relay comprises a first PNPN device in series with a line to be controlled, and a second PNPN device having one end electrode connected to a point of constant potential. The other end electrode of the second device is connected to the inner layer of similar conductivity of the first device. A control circuit is connected to an inner layer of the second device.

Description

United States Patent 72] Inventor Einar A. Aagaard Emrnasingel, Eindhoven, Netherlands [21 Appl. No. 684,240

[22] Filed Nov. 20, 1967 [45] Patented Feb. 16, 1971 [73] Assignee U-S. Philips Corporation New York, N.Y. a corporation of Delaware [32] Priority Nov. 30, 1966 [33] Netherlands [54] ELECTRONIC RELAY ARRANGEMENT Primary Examiner-Stanley T. Krawczewicz Anomey- Frank R. Trifari ABSTRACT: An electronic relay comprises a first PNPN device in series with a line to be controlled, and a second PNPN device having one end electrode connected to a point 13 owns 12 Drawing Figs of constant potential. The other end electrode of the second .[52] [1.8. CI 307/252, device'is connected to the inner layer of similar conductivity 307/303, 307/305 of the first device. A control circuit is connected to an inner [51] hit. ,H03k 5/20 layer of the second device.

001?? CIRCUIT l t P N P N L-. 211

210 I LEAKAGE l :CDRRENT ("NWT ELECTRONIC RELAY ARRANGEMENT The invention relates to an electronic relay circuit arrangement comprising semiconductor subassemblies and has for its object to provide a new design of such an electronic relay arrangement having optimum contact and transmission properties and suitable to be integrated in a simple. manner in a semiconductor body.

The electronic relay arrangement according to the invention is characterized by the combination of a four-layer transistor included in an output circuit and a four-layer transistor included in a control circuit, each four-layer transistor comprising four consecutive layers of semiconductor material alternately of P- and N-type conductivities, forming three PN-junctions with each other an outer layer of the four-layer transistor included in the control circuit being connected to a point of constant potential, whereas the other outer layer is connected to an inner layer of the same conductivity type of the four-layer transistor included in the output circuit, whilst there are provided control circuits for controlling one of the inner layers of the four-layer transistor included in the control circuit. A Y

The invention and its advantages will be described more fully with reference to the FIGS.

FIG. 1 shows the main partsof an electronic relay arrangement.

FIG. 2 shows one embodiment of a particular electronic relay arrangement of the type shown in FIG. 1.

FIG. 3 shows a variant of the electronic'relay arrangement of FIG. 2.

FIG. 4 shows an electronic relay arrangement having two types of output circuits.

FIG. 5 shows one embodiment of a particular electronic relay arrangement of the type shown in FIG. 4.

FIGS. 60, 6b, and 6c show a control circuit and an equivalent crystal arrangement and FIGS. 7a, 7b, 7c, and 7d show an output circuit and an equivalent crystal arrangement.

FIG. 1 shows the main parts of an electronic relay arrangement. This electronic relay arrangement serves in general for acting (opening and closing) upon current circuits under the control of an input circuit 100. The output 101 of the input circuit 100 is connected to the input 102 of a control circuit 103. The input circuit may in general be connected to n control circuits. This is indicated in the FIG. by a multiple sign n between the output 101 and the input 102. The control circuit may have four

outputs

104, 105, 106 and 107. The output 105 is connected to the control input 108 of an output circuit 109. In the same manner the other outputs may be connected each to an output circuit. The control input of an output circuit may in general be connected tom control circuits, which are connected to different input circuits. This is indicated in the FIG. by a multiple sign m between the control input 108 and the output 105. This multiple connection permits of obtaining a logical function, the so-called NQR function. The output circuit 109 may have three

inputs

110, 111, 112 and one output 113. An output circuit may, as an alternative, have one input leakage current from the output circuit. The leakage current circuit is preferably formed by a current source circuit of very high differential resistance. In the short circuit state of the output circuit 109 the output 105 of the control circuit 103 is insulated within the control circuit from any point of constant potential, whereas the

outputs

104, 105, 106 and 107 are insulated one from the other. Then each output is free to adopt the same potential as the associated output circuit, if the latter is in the short circuit state. In the short circuit state of the output circuit the impedance between an input and an output is substantially equal to the impedance of a PN-junction and electrical signals can be transferred between the inputs and the output. These may be direct current signals, alternating current signals or speech signals on a DC carrier. In the transmission of speech signalssubstantially no speech attenuation occurs, since the control input 108 in the control circuit 103 is insulated from any point of constant potential and since the leakage current circuit 115 has a very high differential re- 'sistance. For the transmission of direct current signals of positive or negative polarity or of alternating current signals use is made of bilaterally conducting output circuits. In the short circuit state the impedance between an input and the output is substantially equal to the impedance of two PN-junctions connected in parallel opposition. In the: transmission of alternating-current signals of high amplitude substantially no distortion occurs, since the leakage current circuit ensures that the short circuit state is maintained for arbitrarily low current values and that after the current reversal the short circuit state reappears at arbitrarily low voltage differences.

When the output circuit is in the insulation state, the output 105 within the control circuit 103 is short-circuited to a point of constant potential. The

other outputs

104, 106 and 107 are also short-circuited to the point of constant potential. The short circuit between the output 105 and the point of constant potential serves to hold the output circuit in the insulation state. In this state the inputs, the output and the control input of the output circuit are insulated from each other so that the inputs and the output are each free to assume a potential independent of the control input. In the insulation state of the output circuit a certain amount of leakage current flowsfrom the control input to the output circuit. The short circuit between the point of constant potential in the control circuit 103 and the output 105 has the sum of the leakage current of the output circuit 109 and of the leakage current of the'leakage current circuit 115. The inputs and the output of the output'circuit have, in the insulation state, each a parasitic capacitance with respect to the control input 108. The relative parasitic capacitances are negligible. In the insulation state the control input is connected to a point of constant potential so that the parasitic capacitances of the inputs and of the output are completely decoupled. If for example a speech signal appears at one of the connections 110 to 113, this signal cannot be transferred via the parasitic capacitances to the other connectrons.

FIG. 2 shows an embodiment of a particular electronic relay arrangement of the kind illustrated in FIG. 1. FIG. 2 shows an input circuit 200, the output 201 of which is connected to the and more than one output. With unilaterally conducting output, circuits it is necessary with respect to the direction of the current to distinguish between the inputs and the outputs. This distinction is not due with bilaterally conducting output circuits. To the output circuit 109 is associated a leakage current circuit 115, the output 114 of which is connected to the control-input 108. A

The output circuit 109 may be set by the input circuit 100 by means of the control circuit 103 in two different states. In one state, hereinafter termed the short circuit state, the inputs I10, 111 and 112, the output 113 and, the control input 108 are relatively substantially short-circuited. In the other state, hereinafter termed the insulation state, the inputs, the output and the control input are relatively insulated. The leakage current circuit 115 serves for maintaining the short circuit state of the output circuit for arbitrarily low currents. For this purpose the leakage current circuit withdraws a certain amount of input 202 of a control circuit 203. This circuit comprises the

outputs

204 and 205, the output 205 being connected to the control input 206 of an output circuit 207. The output 204, like the output 205, may be connected to an output circuit. The output circuit 207 has one input 208 and one output 209. To the control input 206 is furthermore connected the output 210 of a leakage current circuit 211. In the input circuit 200 and in the leakage current circuit 211 are indicated points of constant negative potential, designated by minus signs; these are termed hereinafter negative supply points and in the control circuit 203 is indicated a point of constant positive potential marked by a plus sign, termed hereinafter the positive supply point. By way of illustration the voltage of the negative supply points will be assumed to be 74v. and the voltage at the positive supply point to be +6 v. in this embodiment and in the further embodiments. For the output circuits a working range is assumed to amount from zero volt to 74v. 1

The input circuit 200 is represented here by the series combination of a switch 212 and a resistor 213, connected between the output 201 and a negative supply point. The output circuit 207 includes a PNPN-transistor 214, the emitter of which is connected to the input 208 and the collector of which is connected to the output 209. The PNPN-transistor comprises four consecutive layers of semiconductor material alternately of the P- and N-type conductivity, which form three PN-junctions. The base of the transistor 214 is connected to the control input 206. The control circuit 203 includes two PNPN-

transistors

215 and 216, the emitters of which are connected to the positive supply point. The collector of transistor 215 is connected to the output 204 and the collector of transistor 216 is connected to the output 206. The base of transistor 215 and the base of transistor 216 are commonly connected via the series combination of a Zener diode 217 and a resistor 218 to the input 202. Moreover, a resistor 219 is connected in common between the emitter and the base of transistor 216 and the emitter and the base of transistor 215. The leakage current circuit 211 includes a high-ohmic resistor 220, connected between the output 210 and a negative supply point.

For explaining the operation of the electronic relay arrangement it is assumed that the output circuit 207 is included in an external current circuit and that the voltages in the current circuit are located within the working range of the output circuit. In the relay arrangement concerned the PNPN- transistors have two stationary states. In one state the impedance between the emitter and the collector is very low. This state is hereinafter termed the short circuit state. In the other state the impedance between the emitter and the collector is very high. This state is hereinafter termed the cutoff state. A PNPN-transistor in the short circuit state remains in this state when between the emitter and the collector a comparatively low holding current is maintained. The PNPN- transistors used in this case have a holding current which is zero or which may be rendered zero by withdrawing a very small current of for example 1 p.21 from the base. Such PNPN- transistors may be manufactured by the planar diffusion technique. The PNPN-transistors may be moved into the eutoff state by conveying the current passing through the PN- junction between the emitter and the base past this PN-junction. With low current values this can be achieved by connecting the emitter through a resistor to the base. By a suitable choice of the resistor the breakdown voltage between the emitter and the collector can be raised to the breakdown voltage between the base and the collector, when the emitter is interrupted. It will be assumed that the last-mentioned breakdown voltage exceeds 80v.

The

transistors

215 and 216 are in the cutoff state, when the switch 212 is open. When the switch 212 of the input circuit 200 is closed, the Zener diode 217, connected in the reverse direction, becomes conducting in saiddirection and the transistor 216, like the transistor 215, will draw a given base current. This base current need only have a very low value in order to render the transistor 216 conducting. After the breakdown the transistor 216 substantially forms a short circuit between the output 205 and the positive supply point. The potential of the control input 206 of the output circuit 207 thus increases immediately to +6v., so that the PN-junction between the emitter and the base of the transistor 214 is cut off. The voltage by which this PN-junction is cut off is at a minimum 6v. This is the case when the input 208 is directly connected to a supply point of zero volt. After the breakdown the transistor 216 initially draws a current which is equal to or higher than the collector current of the transistor 214 at the instant when the switch 212 is closed. The current passing through the transistor 216 is at any rate limited by the inner base resistance of the transistor 214. This current, which is due to the storage of a charge in the PNPN-transistor 214, decreases automatically according as the transistor 214 approaches the final cutoff state more closely. Moreover, the comparatively high current to be supplied by the transistor 216 after breakdown can be supplied independently of the value of the base current. In the final cutofi' state the two PN- junctions on either side of the base of the transistor 214 are cut off by the +6 v. potential of the control input 206. In this state the control input 206 draws the sum of the leakage currents of the two cutoff PN-junctions. The transistor 206 carries, in addition, the leakage current of the leakage current circuit 211. The total current passing through the transistor 216 is, however, extremely low. The base current withdrawn by the input circuit 200 from the transistor 216 ensures that the transistor 216 continues forming a short circuit for the leakage currents of the output circuit and the leakage current circuit. The cutoff PN-junctions on either side of the base of the transistor 214 each from a barrier layer capacitance. The two barrier layer capacitances are connected on one side to the positive supply point so that the input and the output of the output circuit are completely decoupled. If for example the input 208 has a speech signal, this signal cannot go over to the output 209.

When the switch 212 is opened, the current passing through the transistor 216 is guided by a considerable part around the PN-junction between the emitter and the base through the resistor 219. The current passing through the transistor 216 is very low. At this low current the PN-junction between the emitter and the base has a comparatively high resistance. The resistor 2'19 need then not have a particularly low value to form a detour around the PN-junction. The resistor 219 is determined so that the transistor 216, is cut off. Thus the output 205 is insulated from the positive'supply point. In this state the leakage current circuit 211 withdraws a given base current from the transistor 214, so that the emitter-base capacitance is charged over until the PN-junction between the emitter and the base arrives in theforward direction of conductivity and the holding current is reduced to zero. The transistor 2l4then forms a short circuit for arbitrarily low voltage differences between the emitter and the collector and for arbitrarily low currents. The breakdown voltage of the transistor 216, when the switch 212 is open, exceeds v. owing to the interruption of the emitter current. The maximum voltage which may prevail between the emitter and the collector of the transistor 216 is 80 v. This is the case when the output 209 ofthe output circuit 207 is directly connected to a negative supply point. The maximum voltage is thus lower than the breakdown voltage so that the transistor 216remains cutoff.

The PNPN-transistors are further driven in the saturation state according as the current increases, so that they may be heavily overloaded fora short time without excessive heating. This permits of including the output circuit in a current circuit in which current peaks may occur, for example line current circuits connected to telephone lines.

The Zener diode 217 in the control circuit 203 provides, when the switch 212 in the input circuit 200 is closed, a constant voltage drop equal to the breakdown voltage. This breakdown voltage ischosen to be equal to the voltage of the positive supply point and is in this case 6 v. The input circuit 200 then has at any point a voltage lying in the voltage range from 0 to74v. This voltage range corresponds to the working range of the output circuits. The switch 212 may be replaced by the output circuit-of an electronic relay arrangement as described or by a combinational arrangement of output circuits.

FIG. 3 shows a variant of the electronic relay arrangement of FIG. 2, the control circuit of which has the inverse effect. In FIGS. 3 and 2 the same reference numerals are used as far as possible for corresponding parts. In the followingdescription of FIG. 3 only the differences from the arrangement-of FIG. 2 will be explained. The base of the transistor 215 and the base of the transistor 216 are commonly connected to thecollector of a PNPN-transistor 300, the emitter of which is connected to the positive supply point. The base of the transistor 300is con'- nected through the series combination of a Zener diode 301 and a resistor 302 to the input 202. The base of transistor 300 is furthermore connected through a resistor 303 to the emitter. The bases of

transistors

215 and 216 are furthermore commonly connected to the emitter of a field effect transistor 304, having an insulated control electrode 305. The control electrode 305 and the collector of transistor 304 are connected to a negative supply point. The field effect transistor 304 arranged in this manner, has a high resistance between the emitter-and the collector. When the switch 212 in the input circuit 200 in open, the transistor 304 withdraws a given base current from transistor 216. The holding current of transistor 216 is then substantially'equal to zero. The transistor 216 then continues constituting a short circuit for arbitrarily low currents. The resistor 303 conveys part of the leakage current of the cutoff PN-junction between collector and base of transistor 300 beyond the PN-junction between emitter and base. It is thus achieved that the leakage current flowing from the collector of transistor 300 towards the emitter of transistor 304 is extremely low. The resistor 303 need not have a low value for attaining the purpose aimed at since for low currents the PN-junction between emitter and base has a comparatively high resistance. The resistor 303 may be completely omitted y when the collector leakage current of transistor 300 is so much lower than the emitter current of transistor 304 that still adequate base current is withdrawn from transistor 216 for holding the latter in the short circuit state for arbitrarilylow current values. When the switch 212 is closed a given base current is withdrawn from transistor 300. As a result the transistor 300 conveys a given collector current. This collector current is partly fed to the base of transistor 216. For the other part the collector current flows to the emitter of transistor 304. The portion of the collector current flowing to the base of transistor 216 reduces the current passing through the PN-junction between emitter and base of transistor 216. The collector current is determined so that transistor 216 changes over to the cutoff state. The'operation of the arrangement at the changeover of transistor 216 from the short circuit state to the cutoff state and conversely is otherwise equal to that of the arrangement of FIG. 2. The leakage current circuit 211 of FIG. 3 includes a field effect transistor 306, having an insulated control electrode 307, the emitter being connected to the output 210 and the control electrode and the collector being connected to a negative s'u'pply'point. The advantage of this embodiment of the leakage current circuit is that, as compared with a resistor, a considerably smaller portion of the surface of a crystal circuitry is occupied.

FIG. 4 shows the main parts of an electronic relay arrangement having two different types of output circuits, which may serve for replacing a mechanical relay having make and break contacts. FIG. 4 shows an input circuit 400, the output 401 of which is connected to the input 402 of a control circuit 403.

This circuit has the outputs 404 to 407, the output 405 being connected to the control input 408 of an output circuit 409, having

inputs

410, 411 and 412 and an output 413. To the control input 408 is furthermore connected the output 414 of a leakage current circuit 415. The control circuit 403 has furthermore an additional control output 416, which is con nected to the input 417 of a control circuit 418. This circuit has the outputs 419 to 422, the output 420 being connected to the control input 423 of an output circuit 424, having

inputs

425, 426 and 427 and an output 428. To the control input 423 is furthermore connected an output 429 of a leakage current circuit 430. The multiple signs of FIG. 4 havethe same meaning as in FIG. 1. The

control circuits

403 and 418 are simultaneously acted upon by the inputv circuit 400 and the influence on the control circuit 418 is exerted via the control circuit 403. The operation of the control circuit 418 is the inverse of the operation of the control circuit 403. When the output circuit 409 is driven in the short circuit state by the control circuit 403, the control circuit 418 drives the output circuit 424 in the insulation state and conversely. The outputs of the control circuit 403 are therefore always ina state differing from the outputs of the control circuit 418.

FIG. 5 shows one embodiment of the two control circuits of a given electronic relay circuitry of the kind shown in FIG. 4. FIG. 5 shows an inputcircuit 500, the output 501 of which is output 505, which is connected to the input 506 of the control connected to the input 502 of a control circuit 503, having an output 504. The control circuit 503 has an additional control circuit 507, having an output 508. The control circuit 503 includes a PNPN-transistor 509, the emitter of which is connected to a positive supply point and the collector of which is connected to the output 504. Via the series combination of a Zener diode 510 and a resistor 511 the base is connected to the input 502. A resistor 512 is connected in parallel with the PN-junction between emitter and base of transistor 509. The

- control circuit 503 includes furthermore a PNP-transistor -514, the emitter of which is connected to the positive supply point and the collector of which is connected to the control output 505. The base is connected to the base of transistor 509. The control circuit 503 includes furthermore a field effect transistor 515, having an insulated control electrode 516. The emitter is connected to the output 505 and the collector and the control electrode are connected to a negative supply point. The control circuit 507 includes a PNPN-transistor 517, the emitter of which is connected to a positive supply point and the collector of which is connected to the output 508. The base is directly connected to the input 506.

When the switch 513 is closed, a given base current is derived from the transistor 509 as well as from the transistor 514. The transistor 509 thus becomes conducting and the transistor 514 conveys a given collector current. A portion of this collector current p'asses tothe emitter of transistor 515 and the other portion flows to the base of the transistor 517. The transistor 517 is thus cut off. When the switch 513 is opened, a portion of the current passing through the transistors 509 ahd 514 is conveyed past the PN -junction between the emitter and the base through the resistor 512. The resistor 512 is determined so that the

transistors

509 and 514 are cutoff. From the base of transistor 517 in the control circuit 507 then flows a given base current to the emitter of transistor 515. This base current causes the transistor 517 to conduct. When the switch 513 is open, the output 504 of the control circuit 503 is insulated'from the positive supply point and the output 508 of the control circuit 507 is short circuited relatively to the positive supply point. When the switch 513 is closed, the inverse applies.

FIG. 5 shows a further embodiment of the leakage current circuit. This FIG. shows an output circuit 518, having an input 519, an output 520 and a control input 521. The control input is connected to the output 504 of the control circuit 503 and to the output 522 of the leakage current circuit 523. The latter includes a NPN-transistor 524, the emitter of which is connected to a negative supply point and the collector of which is connected to the output 522. The base is connected to the collector and to the control electrode 525 of a field effect transistor 526, the emitter of which is connected to a positive supply point. The field effect transistor 526 supplies a given, low base current to the transistor 524, which thus withdraws a given collector current from the output 522. This collector current operates as a leakage current for the output circuit 518. In this way a leakage current is obtained which is less dependent upon the voltage of the output 522 than in the embodiments shown in FIGS. 2 and 3. Between the emitter of transistor 526 and the positive supply point a PNPN or a PNP- switching transistor may, if desired, be connected, which switches on the leakage current circuit 523, when this is .required. This switching transistor may be combined with the that in the rest position the dissipation is reduced. This is important, when a great plurality of electronic relay circuits are integrated in one and the same semiconductor bbdy.

FIG. 6a shows a control circuit and FIGS. 6b and 0 shows an embodiment of an equivalent crystal circuit in a plan view and a cross-sectional view respectively. The control circuit of FIG. 6a is the same as the control circuit 503 of FIG. and need not be explained further. In FIG. 6a the semiconductor layers are numbered so that reference can be made to each semiconductor layer by indicating the letter P or N for the conductivity type and the numeral concerned. The crystal structure comprises semiconductor layers produced by contracting several semiconductor layers of the structure of FIG. 6a. Semiconductor layers united by contraction to a single semiconductor layer are designated in FIG. 6a by the same reference numeral. As far as possible the same reference numerals are used in FIGS. 6a, b and c for designating the same parts in order to identify in a simple manner the parts of the structure of FIG. 6a in the crystal structure.

The crystal structure comprises a substrate 618 of N+-type conducting Si, on which a layer N, of high-ohmic Si is provided. To the layer n, are applied by diffusions the P-type conducting layers P, to P By diffusion the layer P is provided with a N+-type conducting layer N, and by diffusion the layer P, is provided with a N+-type conducting layer N,. The latter layer is located at one end of the layer P and overlaps the layer N The connections to the semiconductor layers are formed by metal layers which are in connection with the semiconductor layers concerned through openings in the oxide layer 619, hereinafter termed contact windows. The metal layer 600 is in contact through the window 612 with the elongated P-type conducting layer P,. The ohmic resistance of this layer forms the resistor 607. The PN-junction between the layer P and the N+-type conducting layer N constitutes the Zener diode 608. The part of the layer N which is locatedabove the layer N establishes a connection between the Zener diode and the layer N This connection is located in the proximity of the base zone of the PNPN-structure comprising the layers P,. N,,, P and N,. This structure forms the PNPN- transistor 609. The emitter connection is formed by the metal layer 602, which is in contact through the window 617 with the layer P,. The collector connection is formed by the metal layer 601, which is in contact through the window 614 with the layer N,. The connection between the layers N and N is located near the base zone of the PNPN-transistor 609. This proximity permits a direct action upon the base zone of the PNPN-transistor via the Zener diode. The narrow, elongated portion of the layer P forms the resistor 606. This portion is at its end in contact through a window 613 with the metal layer 605. The contact window 613 is located partly above the layer N The metal layer 605 is in contact through this portion of the contact window with the layer N,,. In order to establish a satisfactory connection with the high-ohmic layer N,,, this connection is made via a N+-type conducting layer provided beneath the contact window on the layer N This layer is not shown in the FIGS. The connection of the metal layer 605 with the layer N permits of acting upon the base zone of the PNPN-transistor 609 via the resistor 606. The layers P,, N, and P form the PNP-transistor 610. The emitter connection is the same as that of the PNPN-transistor 609. The collector connection is formed by the metal layer 604, which is in contact through the contact window 615 with the layer P The broad portion of the layer P, operates on the right-hand side as an emitter for the PNPN-transistor 609 and on the left-hand side as an emitter for the PNP-transistor 610. The good conducting substrate 618 ensures that the base zones of the PNPN-transistor 609 and the PNP-transistor 610 are substantially at the same potential so that they can be affected to the same extent via the Zener diode.

The field effect transistor 611 is formed by the layers P N and P, and the metal electrode 603. The emitter connection is the same as the collector connection of the PNP-transistor 610. The collector connection is formed by the metal layer 603, which is in contact through the contact window 616 with the layer P,. The metal layer extends over the portion of the layer N which is located between the layer P and I and overlaps the layer P Thus the metal layer operates as a control electrode of the field effect transistor.

FIG. 7a shows a bilaterally conducting output circuit and FIGS. 7b, 0 and d show one embodiment of an equivalent crystal structure in a plan view and in two cross-sectional views respectively. The output circuit of FIG. 7a has an input 700 and two

outputs

701 and 702 and one control input 703. The input 700 is connected to the emitters of the PNPN-

transistors

706, and 707, the collectors of which are connected to the

outputs

701 and 702. The

outputs

701 and 702 are furthermore connected individually to the emitters of the PNPN-

transistors

708 and 709, the collectors of which are connected to the input 700. The bases of the four PNPN- transistors are all connected to the control input 703. Between the input and each output is thus arranged the parallel opposition connection of the main current paths of two PNPN- transistors. Which of the two PNPN-transistors becomes conducting, when the control input 703 is insulated from the positive supply point, depends upon the polarity of the voltage difference between the input and the output. In the insulation state of the output circuit all PNPN-transistors are cut off. The

' control input 703 is connected to the collector of an NPN- transistor 710, operating as a leakage current circuit, the base and emitter connections of which are designated by 704 and 705 respectively. The base can be controlled in the manner referred to in FIG. 5.

The crystal structure comprises a N+-type conducting substrate 721, on which a N-type conducting layer N, is provided. The layer N is provided with the P-type conducting layers P, to P, and the N+-type conducting layer N,. The layers P,., P P and P are provided with the N+-type conducting layers N,, N N and N... The control input is formed by the metal layer 703, which is in contact through the window 717 with the layer N,,. The layers P,, N P, and N, form the PN PN- transistor 706 and the layers P,, N P and N form the PN PN- transistor 707. The layer P, operates on the left-hand side as an emitter for the transistor 706 and on the right-hand side as an emitter for the transistor 707. The emitter connections are formed by the metal layer 700, which is in contact through the window 715 with the layer P,. The collector connections are formed by the metal layers 701 and 702, which are in contact through the windows 711 and 712 respectively with the layers N, and N. The layers P,, N P N, form the PNPN-transistor 708 and the layers P N,,, P,, and N, form the PNPN-transistor 709. The layers P and N operate on the right-hand side as a collector for the transistor 708 and on the left-hand side as a collector for the transistor 709. The collector connections are formed by the metal layer 700, which is in contact through the contact window 716 with the layer N The metal layer 700 operates, in addition, as a conducting connection between the common collector of the

transistors

708 and 709 and the common emitter of the

transistors

706 and 707. The metal layer 700 is the input of the output circuit. The emitter connections of the

transistors

708 and 709 are formed by the metal layers 701 and 702 respectively, which are in contact through the

windows

713 and 714 respectively with the layers P and P,. The metal layer 701 operates, in addition, as a conducting connection between the collector of the transistor 706 and the emitter of the transistor 707 and forms an output of the output circuit. In a similar manner the metal layer 702 constitutes a conducting connection between the collector of the transistor 707 and the emitter of the transistor 709 and like the metal layer 701 it forms an output of the output circuit.

The NPN-transistor 710 is formed by the layers N P,'and N The emitter connection is formed by the metal layer 705, which is in contact through the window 718 with the layer N,. The base connection is formed by the metal layer 704, which is in contact through the window 719 with the layer P,. The lateral distance of the NPN-transistor 710 from the PNPN- transistors is determined so that the layer P, cannot collect the minority carriers that are introduced into the layer N, from the emitter of any PNPN-transistor.

We claim:

1. An electronic relay comprising a first four-layer transistor device, an input circuit connected to one outer layer of said first device and an output circuit connected to the other outer layer of said first device, said input and output circuits having a selected potential range, means for forward biasing said first device including a source of leakage current connected to said inner layer, a second four-layerdevice having one outer layer connected to a point of constant potential having a potential outside of said selected potential range, means for controlling the conduction of said first device by said second device withdrawing said leakage currentfrom said first device comprising means interconnecting the other outer layer of said second device and the inner layer of said first device of the same conductivity, and a direct current control circuit means connected to an inner layer of said second device.

2. A relay as claimed in claim 1 further comprising a first resistor coupled between said source of constant potential and said inner layer of said second device.

3. A relay as claimed in claim 2 further comprising a series circuit comprising a Zener diode-and second resistor coupled between .said control circuit and said inner layer of said second device.

4. A relay as claimed in claim 1 wherein said control circuit comprises a three-layer transistor having outerlayers coupled to said outer layer of said second device which is coupled to said point of constant potential and said inner layer of said second device respectively, said outer layers of said threelayer device being of opposite conductivity type from said inner layer of said second device.

5. A relay as claimed in claim 4 further comprising a source of leakage current coupled to said inner layer of said second .1 device. 7 5

6. A relay as claimed in claim 4 further comprising a series circuit including a Zener diode and a resistor coupled between the inner layer of said three-layer transistor and said control circuit.

7. A relay as claimed in claim 4 further comprising a resistor coupled between said point of constant potential and the inner layer of said three-layer transistor.

8. A relay as claimed in claim 2 further comprising a threelayer transistor device having outer layers coupled to said point of constant poteniial and an output terminal respectively, and an inner layer coupled to said inner layer of said second device. 1

9. A relay as claimed in claim 8 further comprising a leakage current source coupled to said output terminal.

10. A relay as claimed in claim 1 wherein said leakage current source comprises a field effect transistor.

1 11. A relay as claimed in claim 1 wherein said leakage current source comprises a three-layer transistor having outer layers of the same conductivity type as the inner layer of said first device and means for controlling the current in the inner layer of said three-layer transistor.

12. A relay as claimed in claim 11 wherein said current control means comprises a field effect transistor.

13. A relay as claimed in claim 1 further comprising a third four-layer transistor device having outer layers coupled in parallel opposition with respect to said first device and an inner layer coupled to the inner layer of said first device.

Claims

1. An electronic relay comprising a first four-layer transistor device, an input circuit connected to one outer layer of said first device and an output circuit connected to the other outer layer of said first device, said input and output circuits having a selected potential range, means for forward biasing said first device including a source of leakage current connected to said inner layer, a second four-layer device having one outer layer connected to a point of constant potential having a potential outside of said selected potential range, means for controlling the conduction of said first device by said second device withdrawing said leakage current from said first device comprising means interconnecting the other outer layer of said second device and the inner layer of said first device of the same conductivity, and a direct current control circuit means connected to an inner layer of said second device.

3. A relay as claimed in claim 2 further comprising a series circuit comprising a Zener diode and second resistor coupled between said control circuit and said inner layer of said second device.

4. A relay as claimed in claim 1 wherein said control circuit comprises a three-layer transistor having outer layers coupled to said outer layer of said second device which is coupled to said point of constant potential and said inner layer of said second device respectively, said outer layers of said three-layer device being of opposite conductivity type from said inner layer of said second device.

5. A relay as claimed in claim 4 further comprising a source of leakage current coupled to said inner layer of said second device.

8. A relay as claimed in claim 2 further comprising a three-layer transistor device having outer layers coupled to said point of constant potential and an output terminal respectively, and an inner layer coupled to said inner layer of said second device.

11. A relay as claimed in claim 1 wherein said leakage current source comprises a three-layer transistor having outer layers of the same conductivity type as the inner layer of said first device and means for controlling the current in the inner layer of said three-layer transistor.