JPS60148223A - High speed diode switch circuit - Google Patents

Abstract

PURPOSE:To obtain an electronic switch with good balance and possible for high speed switching by adding an ECL circuit possible for circuit integration to a diode bridge circuit and controlling the ECL circuit. CONSTITUTION:When a smaple command signal V1<V2 is given from a controler 74, a transistor (TR) Q1 of the ECL circuit 83 is turned off and a TRQ2 is turned on, a current from a current source 21 flows to a bridge comprising diodes D41-43, added with a current from a current source 22 and flows to a current source 23 through the TRQ2. Thus, the D41-43 are conductive, and an output voltage eout at a terminal 12 changes in following to an input voltage ein from a terminal 11. Since the relation of reference voltage Vref>=ein>=-Vref exists in this case, D47, 48 are turned off. When a hold command signal V1>V2 us given from the controller 74 next, the TRQ1 is turned on and the TRQ2 is turned off, a voltage of a reference voltage decreases the potential at a connecting point 91 through the D47, the D41, 43 are turned off, the current of the current source 22 flows to the reference voltage source 82 through the D48, the D42, 44 are turned off so as to hold the voltage eout.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a high-speed switch circuit configured with four diodes as a bridge.

Traditionally, electronic switches such as transistors and FETs (
Field effect transistors), diodes, etc. are used. Among these, bridged diodes are capable of high-speed switching and are used as high-speed sampling switches. FIG. 1 shows a diagram for explaining the operation of the circuit. In the figure, 11 is an input terminal, 12 is an output terminal, and 21.22 are current sources whose current values are equal. 41.42.43.44 are diodes,
constitutes a bridge. In this case switches 51 and 5
2 on and off simultaneously to input terminal 11 and output terminal 12.
Therefore, the balance of the switching time of the switch becomes an issue. In this invention, by adding a circuit that can integrate the switching of the switch, the switching time can be balanced, and the switching can be performed at high speed and with high precision.

<Description of Prior Art> There is a method of using a pulse transformer to switch the switches 51 and 52 in a well-balanced manner.

FIG. 2 shows the conventional circuit. Components that are the same as in FIG. 1 are designated by the same reference numerals. In the figure, reference numeral 61 denotes a pulse transformer, which is controlled by a controller 73 to make conductive or non-conductive between the input terminal 11 and the output terminal 12 through a diode bridge. However, this pulse transformer has the disadvantage that it is difficult to miniaturize and integrate, and it requires a large amount of electric power.

As shown in FIG. 3, there is also a method of using switch driver circuits 71 and 72 constructed from active devices such as transistors as conventional circuits. In the figure, 73 is a controller, and switch driver circuits 71 and 72
It controls the In this circuit, 71 is a switch driver circuit for the source, and 72 is a driver circuit for the sink, so they are NPN) transistors,
There is no choice but to use a PNP transistor. however,
Since the N'PN) transistor and the PNP) laser resistor have different characteristics, their drive waveforms are different, and it is very difficult to ensure balance in switching time. Therefore, it is conceivable to insert a delay circuit to ensure the balance of switching times, but this has the disadvantage that it cannot be operated at high speed.

<Purpose of the Invention> This invention adds an integrable circuit to an electronic switch composed of a diode bridge, thereby making it possible to turn on and off at high speed and with high precision while maintaining balance during current switching. It is.

<Summary of the Invention> The high-speed switch circuit according to the present invention has current directions of both the first and second current sources directed toward the source or toward the sink, and a reference voltage is connected through the diode to the connection point between the current source and the diode bridge. A power source is connected, and the interaction between the current source and the diode bridge 7 is performed using an ECL circuit.

<Embodiment of the Invention> FIG. 4 shows an embodiment of the invention. This is applied to a sample/hold circuit, and the current directions of the first and second current sources are both directed toward the source. In the figure, the same parts as in FIG. 1 are indicated by the same symbols. 83 is an ECL circuit. The first current source 21 and the second current source 22 supply current in the direction of the diode bridge, and when these currents do not flow to the diodes 47 and 48, they flow to the third current source 23 through the ECL circuit 83. That is, the current values 11, lz, and I* of each current source have a relationship of i3 wit +12. In addition, 74 in the figure is a controller, and the ECL
The base voltage v1. of the first transistor Q and the second transistor Q2 of the circuit 83. ．． v2.

Further, the absolute value of the reference voltage V ref of the first and second reference voltage sources is set to be larger than or about the same as the absolute values of the input voltage et11 and the output voltage e out.

Next, the operation will be explained. When a sample command signal (v+ <V2) is applied from the controller 74, the first transistor Q is turned off and the second transistor Q2 is turned on. Therefore, the current from the first current source 21 flows through the diodes 41 to
44, is added to the current from the second current source 22, and flows to the third current source 23 through the second transistor Qg. As a result, the bridge made up of diodes 41 to 44 becomes conductive, and the output voltage e out changes to follow the input voltage ein. At this time, the voltages at each connection point of the diode bridge become equal, and ei
Since a≧−■r*f and e i 11≦V rat, the first diode 47 and the second diode 48 are turned off.

Next, the controller 74 sends a hold command signal (Vl>v2
), the first transistor Q is turned on and the second transistor Q2 is turned off. Therefore, the current from the first current source 21 passes through the first transistor Q1 to the third current source 21.
It flows to 3. At this time, since the current value i3 of the third current source 23 is larger than the current value 11 of the first current source 21, the remaining current (i, -i+) is transmitted from the first reference voltage source 81 to the contact 91 through the first diode 47. flows to Therefore, the voltage at the contact 91 becomes -v ref, and V r a f≦e, l
,, -V, f≦80□, so the diode 41.4
3 is in the off state. Further, since the second transistor Q2 is off, the current from the second current source 22 flows to the second reference voltage source 82 through the second diode 48. Therefore, the voltage at the contact 92 becomes V raf , and V raf≧
Since e, 11, V raf≧e out, the diodes 42 and 44 are also turned off. That is, the diode 41~
The bridge consisting of 44 becomes non-conducting and the output voltage e
. , t are held at a constant voltage.

Therefore, an ECL that can be integrated into a diode bridge circuit
A circuit 83 and a controller 74 are added, and the E
By simply controlling the base voltages of the first transistor Q1 and the second transistor Q2 of the CL circuit 83, the input terminal 11
, the output terminals 12 can be switched between conduction and non-conduction at high speed. Although the first and second current sources are both described as source sources in FIG. 4, they can also be operated as sink sources. In this case, it is easy to understand that the polarity directions of the first and second reference voltage sources, the third current source, etc. are reversed.

According to this switching circuit, since both the transistors connected to the contacts 91 and 92 are of the same type as NPN or PNP, the time difference in switching time can be minimized, good balance can be achieved, and high-speed switching can be achieved. It becomes possible.

FIG. 5 shows another example of a high speed diode switch circuit according to the present invention. This is used as a switch for an integral sample/hold circuit consisting of resistors 94 and 95, a capacitor 32, and an operational amplifier 93. Since the output terminal of the high-speed switching circuit is approximately Ov, the first reference voltage source 81 and the second reference voltage source 82 can be set to the ground potential.

When the sample command signal (v, <Vl) is applied from the controller 74, the diode bridge circuit becomes conductive as in the case of FIG. Therefore, the voltage e611t at the output terminal 14 follows the voltage eln at the input terminal 13 and changes according to the relational expression teout-ein. In addition, the controller 74 sends a hold command signal (V
l>Vl), the diode bridge circuit becomes non-conductive and the output voltage e out is held at a constant voltage.

Therefore, with the above configuration, it is possible to switch between the sample state and the bold state at extremely high speed.

<Effects of the Invention> As explained above, according to the present invention, an electronic switch with good balance and capable of high-speed switching can be obtained by adding an ECL circuit that can be integrated to a diode bridge circuit and controlling this. In practical use, the effect is great.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram for explaining the invention in detail, Figure 2 is a circuit diagram for explaining the invention in detail.
3 and 3 are circuit diagrams of a sample/hold circuit using a conventional diode switch circuit, FIG. 4 is a sample/hold circuit using a high speed diode switch circuit according to the present invention, and FIG. 5 is a circuit diagram of a sample/hold circuit using a high speed diode switch circuit according to the present invention. This is an example. 1113F input terminal, 12.14: Output terminal, 21: First current source, 22: Second current source, 23: Third current source, 31.32: Capacitor, 41.42.43.44: Diode, 45. 46.4
7.48: Diode, 51.52: Switch, 61: Pulse transformer, 71.72: Switch driver circuit, 73.74: Controller, 81: First reference voltage source, 82: Second reference voltage source, 83: ECL circuit, 93: Operational amplifier, 94.95: Resistor Patent applicant: Takeda Riken Kogyo Co., Ltd. Figure 2 Figure 3 +V Figure 4 10V Figure 5

Claims (1)

[Claims] (1) A: a diode bridge made up of four diodes; B: a first current source that supplies current to one of the current supply terminals of the diode bridge; and C1: the other current supply terminal of the diode bridge. a second current source supplying a current; D. a first reference voltage source connected through a first diode to the junction of the diode bridge and the first current source; E. the diode bridge; a second reference voltage source connected to the connection point with the second current source through a second diode; F, the collector of the first transistor is connected to the connection point between the diode bridge and the first current source; , the collector of the second transistor is connected to a connection point between the diode bridge and the second current source, and the emitters of the second and second transistors are commonly connected to a third current source. Emiso-coupled logic (hereinafter referred to as E
It's called CL. ) circuit, G, and a controller for controlling the base voltage of each transistor of the ECL circuit.