This disclosure relates to an electrical circuit and a method of operating an electrical circuit.
To drive light-emitting components, in particular light-emitting diodes and laser diodes, electrical circuits may be used. The electrical circuits then generally comprise a terminal for the light-emitting component at which a supply voltage or a supply current may be provided for the light-emitting component. In addition, the electrical circuit may comprise a control input on the basis of which the supply voltage or the supply current for the light-emitting component may be controlled. Thus, the supply voltage or the supply current is switched on and off, wherein inductances within the control may have the effect that the supply voltage or the supply current is present at the light-emitting component only after a certain rise time. The rise time has the effect that the light-emitting component may not be operated such that the light-emitting component generates a short light pulse that is shorter than the rise time.
It could therefore be helpful to provide an electrical circuit with which a light-emitting component may be operated such that a short light pulse of the order of magnitude of a few nanoseconds may be generated by the light-emitting component and an operating method for such an electrical circuit that enables the short light pulses to be generated.
We provide an electrical circuit that drives a light-emitting component, the circuit including a parallel circuit including a capacitor; and a switching element, wherein a first terminal for a voltage supply connects to a first contact of the capacitor and a second terminal for a voltage supply connects to a second contact of the capacitor, the switching element includes a first electrical switch including a first input for a first switching signal, a second electrical switch including a second input for a second switching signal, and a third terminal and a fourth terminal, the third terminal and the fourth terminal form a component terminal for the light-emitting component, a first current path may be switched to be conducting by the first switch, the first current path includes the component terminal, a second current path may be switched to be conducting by the second switch, and the second current path is in parallel with the component terminal.
We also provide a method of operating the electrical circuit that drives a light-emitting component, the circuit including a parallel circuit including a capacitor; and a switching element, wherein a first terminal for a voltage supply connects to a first contact of the capacitor and a second terminal for a voltage supply connects to a second contact of the capacitor, the switching element includes a first electrical switch including a first input for a first switching signal, a second electrical switch including a second input for a second switching signal, and a third terminal and a fourth terminal, the third terminal and the fourth terminal form a component terminal for the light-emitting component, a first current path may be switched to be conducting by the first switch, the first current path includes the component terminal, a second current path may be switched to be conducting by the second switch, and the second current path is in parallel with the component terminal, including switching the second electrical switch to have continuity for electric current based on a second switching signal at the second input, switching the first switch to have continuity for electric current based on a first switching signal at the first input, switching the second electrical switch to be blocking for electric current based on a second switching signal at the second input, and switching the first switch to be blocking for electric current based on a first switching signal at the first input.
We further provide an electrical circuit that drives a light-emitting component, including a parallel circuit including a capacitor; and a switching element, wherein a first terminal for a voltage supply connects to a first contact of the capacitor and a second terminal for a voltage supply connects to a second contact of the capacitor, the switching element includes a first electrical switch including a first input for a first switching signal, a second electrical switch including a second input for a second switching signal, and a third terminal and a fourth terminal, the third terminal and the fourth terminal form a component terminal for the light-emitting component, a first current path may be switched to be conducting by the first switch, the first current path includes the component terminal, a second current path may be switched to be conducting by the second switch, the second current path is in parallel with the component terminal, the component terminal connects in parallel with the second electrical switch, and the first electrical switch connects in series with the parallel circuit comprising component terminal and second electrical switch.
We further yet provide the electrical circuit that drives a light-emitting component, including a parallel circuit including a capacitor; and a switching element, wherein a first terminal for a voltage supply connects to a first contact of the capacitor and a second terminal for a voltage supply connects to a second contact of the capacitor, the switching element includes a first electrical switch including a first input for a first switching signal, a second electrical switch including a second input for a second switching signal, and a third terminal and a fourth terminal, the third terminal and the fourth terminal form a component terminal for the light-emitting component, a first current path may be switched to be conducting by the first switch, the first current path includes the component terminal, a second current path may be switched to be conducting by the second switch, the second current path is in parallel with the component terminal, the component terminal connects in parallel with the second electrical switch, and the first electrical switch connects in series with the parallel circuit comprising component terminal and second electrical switch, wherein a light-emitting component connects to the component terminal, wherein the circuit includes conductor tracks on a printed circuit board, a first conductor track and a second conductor track are arranged on the printed circuit board, the first contact of the capacitor is a first bottom side contact and arranged on the first conductor track, the second contact of the capacitor is a second bottom side contact and arranged on the second conductor track, the light-emitting component includes a third bottom side contact and a first top side contact, the third bottom side contact is arranged on the first conductor track, the first electrical switch includes a fourth bottom side contact and a second top side contact, the fourth bottom side contact is arranged on the second conductor track, the second electrical switch includes a fifth bottom side contact and a third top side contact, the fifth bottom side contact is arranged on the first conductor track, the first top side contact connects to the second top side contact by a bond wire, and the first top side contact connects to the third top side contact by a bond wire.
100 Electrical circuit
101 First terminal
102 Second terminal
103 Printed circuit board
104 First conductor track
105 Second conductor track
106 Third conductor track
107 Region
108 Taper
110 Component
111 Third terminal
112 Fourth terminal
113 First top side contact
120 Capacitor
121 First contact
122 Second contact
130 Switching element
131 First current path
132 Second current path
140 First electrical switch
141 First input
142 Second top side contact
150 Second electrical switch
151 Second input
152 Third top side contact
160 Resistor
161 Fifth terminal
162 Sixth terminal
170 Bond wire
An electrical circuit that drives a light-emitting component comprises a parallel circuit comprising a capacitor and a switching element. A first terminal for a voltage supply connects to a first contact of the capacitor. A second terminal for a voltage supply connects to a second contact of the capacitor. The first and second terminals for the voltage supply thus provide an electrical supply voltage for the circuit and thus also for the light-emitting component. The switching element connected in parallel with the capacitor comprises a first electrical switch comprising a first input for a first switching signal, a second electrical switch comprising a second input for a second switching signal, and a third terminal and a fourth terminal. The third and fourth terminals form a component terminal for the light-emitting component. A first current path may be switched to be conducting by the first switch, wherein the first current path comprises the component terminal. A second current path may be switched to be conducting by the second switch, wherein the second current path is in parallel with the component terminal.
With such a circuit, first, the second switch may be switched to have continuity for electric current. Since the second switch is in parallel with the component terminal, the light-emitting component may thus be bridged. The current flowing on account of the supply voltage flows through the second switch. If the first current path is then switched to be conducting, the light-emitting component, at the component terminal, continues to be bridged by the second switch. If the second switch is subsequently switched to be blocking, on account of the current already flowing, the inductance of the electrical circuit changes only to a very small extent. As a result, the rise time caused by the inductance is shortened such that the full supply voltage is present at the light-emitting component within a few nanoseconds. As a result, a light pulse that is present very shortly after the corresponding switching of the electrical circuit may be generated by the light-emitting component. If the voltage supply is then interrupted by the first switch being switched to be blocking, a short light pulse of the light-emitting component comprising a pulse length of a few nanoseconds may be generated as a result.
The component terminal may connect in parallel with the second electrical switch. The first electrical switch may connect in series with the parallel circuit comprising component terminal and second electrical switch. In this example, the current flows through the first switch and the second switch before the second switch is switched to be blocking. Since an internal resistance of a light-emitting component connected to the component terminal is significantly greater than an internal resistance of the second switch, approximately no current flows through a light-emitting component connected to the component terminal. After the second switch has been switched to be blocking, however, the entire supply voltage may be present at the light-emitting component or the component terminal, wherein only the inductances of the second switch and the light-emitting component need be taken into account for the rise time.
The first switch may connect in series to the component terminal. The second switch may connect in parallel to the series circuit comprising first switch and component terminal. In this example, too, the light-emitting component is bridged via the second switch at the component terminal. If the second switch is then switched to be blocking, the entire current flows through the first switch and the light-emitting component. In this example, the inductances of the second switch, the first switch and the light-emitting component need to be taken into account for the rise time.
The first electrical switch and/or the second electrical switch may be transistors, in particular field effect transistors. Transistors or field effect transistors are well suited to a circuit for a light-emitting component with which short rise times may be realized.
A light-emitting component may connect to the component terminal. The light-emitting component is thus part of the electrical circuit or the electrical circuit is part of the light-emitting component. A compact arrangement of the light-emitting component and of the electrical circuit, for example, on a printed circuit board, may be realized as a result. The electrical circuit and the light-emitting component may be realized in an integrated circuit.
The light-emitting component may comprise a diode laser. The diode laser may comprise at least two pn junctions connected in series. The diode laser may be in particular a so-called triple junction laser comprising three pn junctions. Such a triple junction diode laser requires a supply voltage of approximately 20 volts or a supply current of approximately 30 amperes. On account of the high voltages and currents occurring on account of the supply voltage or the supply current, inductive effects are of great importance when the triple junction laser is switched on and off. The circuit thus makes it possible to operate a triple junction laser in a pulsed manner, wherein the pulse length is in the range of a few nanoseconds. With a conventional circuit consisting of a switch connected in series with the triple junction laser, pulsed operation with such short pulse lengths would not be possible.
The circuit may comprise conductor tracks on a printed circuit board. A first conductor track and a second conductor track may be arranged on the printed circuit board. The first contact of the capacitor may be a first bottom side contact and arranged on the first conductor track. The second contact of the capacitor may be a second bottom side contact and arranged on the second conductor track. The light-emitting component may comprise a third bottom side contact and a first top side contact. The third bottom side contact of the light-emitting component may be arranged on the first conductor track. The first electrical switch may comprise a fourth bottom side contact and a second top side contact. The fourth bottom side contact of the first electrical switch may be arranged on the second conductor track. The second electrical switch may comprise a fifth bottom side contact and a third top side contact. The fifth bottom side contact of the second electrical switch may be arranged on the first conductor track. The first top side contact of the light-emitting component may connect to the second top side contact of the first electrical switch by a bond wire. A compact arrangement of the light-emitting component, of the capacitor and of the electrical switches on the printed circuit board may be achieved as a result.
The first top side contact of the light-emitting component may connect to the third top side contact of the second electrical switch by a bond wire. In this example, therefore, the light-emitting component and the second electrical switch connect in parallel with one another, while the first electrical switch connects in series with the parallel circuit comprising light-emitting component and second electrical switch.
The second top side contact of the first electrical switch may connect to the third top side contact of the second electrical switch by a bond wire. In this example, therefore, light-emitting component and first electrical switch connect in series, while the series circuit comprising light-emitting component and first electrical switch connect in parallel with the second electrical switch.
The electrical circuit may furthermore comprises a resistor. The resistor may connect in series with the switching element. The electrical circuit may comprise a fifth terminal and a sixth terminal, wherein the fifth terminal and the sixth terminal are configured to tap off a voltage dropped across the resistor. By virtue of the fact that the resistor connects in series with the switching element, a voltage is dropped across the resistor during the operation of a light-emitting component at the electrical circuit, which voltage may be measured by the fifth and sixth terminals. As long as the electric current flows through the second electrical switch, that is to say the light-emitting component is bridged, the voltage drop across the electrical resistor is greater than in the operating mode in which the second electrical switch is switched to be blocking and the electric current flows through the light-emitting component. The light pulse emitted by the light-emitting component may thus be detected as a result of the change in the voltage drop across the resistor.
The electrical circuit may comprise a resistor, wherein the resistor connects in series with the switching element. The electrical circuit may comprise a fifth terminal and a sixth terminal configured to tap off a voltage dropped across the resistor. The circuit may comprise conductor tracks on a printed circuit board, wherein a first conductor track, a second conductor track and a third conductor track are arranged on the printed circuit board. The first contact of the capacitor may be a first bottom side contact and arranged on the first conductor track. The second contact of the capacitor may be a second bottom side contact and arranged on the second conductor track. The light-emitting component may comprise a third bottom side contact and a first top side contact, wherein the third bottom side contact is arranged on the third conductor track. The first electrical switch may comprise a fourth bottom side contact and a second top side contact, wherein the fourth bottom side contact is arranged on the second conductor track. The second electrical switch may comprise a fifth bottom side contact and a third top side contact, wherein the fifth bottom side contact is arranged on the third conductor track. The first top side contact may connect to the second top side contact by a bond wire. The resistor may comprise a sixth bottom side contact and a seventh bottom side contact, wherein the sixth bottom side contact is arranged on the first conductor track and the seventh bottom side contact is arranged on the third conductor track, and the fifth terminal is arranged on the first conductor track and the sixth terminal is arranged on the third conductor track.
The resistor may be a taper of a conductor track. The cost-effective production of a resistor used to detect a light pulse is possible as a result.
In a method of operating an electrical circuit, first, the second electrical switch is switched to have continuity for electric current on the basis of a second switching signal at the second input, wherein afterward the first switch is switched to have continuity for electric current on the basis of a first switching signal at the first input. After that, the second switch is switched to be blocking for electric current on the basis of the second switching signal at the second input. After that, in turn, the first switch is switched to be blocking for electric current on the basis of the first switching signal at the first input. As a result of the second switch being switched to be blocking, the electric current is directed to the component terminal and thus to the light-emitting component. As a result, the light-emitting component emits light. As a result of the first switch being switched to be blocking, the supply of current to the light-emitting component is interrupted.
The time period between switching the second switch to be blocking and switching the first switch to be blocking may be less than 10 nanoseconds, in particular less than 5 nanoseconds and in particular 2 nanoseconds. A light pulse of the light-emitting component shorter than 10 nanoseconds, in particular shorter than 5 nanoseconds, and in particular comprising a pulse length of 2 nanoseconds, is generated as a result.
The voltage dropped across the resistor may be measured by the fifth and sixth terminals. By virtue of the measured resistance, it is possible to detect whether the light-emitting component has emitted a light pulse.
The above-described properties, features and advantages and the way in which they are achieved will become clearer and more clearly understood in association with the following description of examples explained in greater detail in association with the drawings.
In one example, a time period between switching the second switch 150 to be blocking and switching the first switch 140 to be blocking is less than 10 ns, in particular less than 5 ns, in particular 2 ns. Short pulses in the nanoseconds range may be generated as a result.
In one example, the first electrical switch 140 is a transistor, in particular a field effect transistor. In another example, the second switch 150 is a transistor, in particular a field effect transistor.
While the electric current flows through the second electrical switch 150, a higher voltage is dropped across the resistor 160, that is to say at the points in time at which the electric current flows through a light-emitting component connected to the component terminal 111, 112. As a result, by measuring the voltage drop by the fifth terminal 161 and the sixth terminal 162, it is possible to detect when a current flows through the light-emitting component and thus when the light-emitting component emits light.
In contrast to the illustration in
In one example, the light-emitting component 110 is a diode laser. In another example, the light-emitting component is a diode laser comprising at least two pn junctions connected in series, in particular a so-called triple junction diode laser comprising three pn junctions connected in series. Such a triple junction diode laser requires a supply voltage of approximately 20 volts and has an operating current of approximately 30 amperes. By virtue of these high values for the supply voltage and the operating current, reduction of the inductances during the switching process such as may be realized with the circuit 100 is particularly advantageous. By the circuit 100, a triple junction diode laser may be operated with short switching times.
Likewise, in this example, the bond wires 170 may be arranged analogously to
Although our circuits and methods have been more specifically illustrated and described in detail by preferred examples, this disclosure is not restricted by the examples disclosed and other variations may be derived therefrom by those skilled in the art without departing from the scope of protection of the appended claims.
This application claims priority of DE 1 2017 100 879.9, the subject matter of which is incorporated herein by reference.
Number | Date | Country | Kind |
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10 2017 100 879.9 | Jan 2017 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/050945 | 1/16/2018 | WO | 00 |