JPS5848531A - High frequency switch - Google Patents

Abstract

PURPOSE:To attain switching of a large input signal and to eliminate the need for other oscillating sources to obtain a high voltage, by rectifying a part of a high frequency input power and superimposing the result on a bias of a transistor for high frequency switch control. CONSTITUTION:A part of a high frequency input power applied to a terminal T1 is picked up at a directional coupler 29 and a negative voltage is picked up at a voltage multiplying rectifier consisting of diodes 21, 22, capacitors 25, 27 or diodes 23, 24 and capacitors 26, 28. This voltage is superimposed on a terminal voltage at P2, P3 and applied to PIN diodes 1, 2 via coils 14, 15. Thus, since the diode 1 is reverse-biased with a voltage summed with a voltage rectifying a part of the input high frequency signal in addition to a voltage at a terminal T4, a large input power can also be interrupted. Since this reverse voltage is obtained by detecting a part of an input power, other oscillating sources for high voltage generation are not required.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-power high-frequency switch using a semiconductor element.

An example of a conventional high-frequency switch of this type is shown in Fig. 1. In the same figure, 1.2 is a PIN diode, 3°4 is a switching transistor ss s6t "s8
is a capacitor, 9, 10.11 is a resistor, 12゜13.1
4.15 is a coil, T is an input signal terminal, T2. T3
is the output signal terminal s "4 is the transistor 3. If the potential of the input terminal T5 is set to approximately the same potential as the voltage of the power supply voltage terminal T4, and the potential of the terminal T6 is set to the ground potential, the PI
A forward current flows through the N diode 2, and the 24 points have approximately the same potential as the terminal T4.

On the other hand, since the potential at point 22 is the ground potential, the PIN diode 1 is reverse biased with a voltage approximately equal to the voltage at the terminal T4. Therefore, the high frequency input applied from terminal T appears at terminal T, and the signal path to terminal T2 is blocked. At this time, the maximum power that can be handled by this switch is approximately O6 2Zo. (However, Vcc is the voltage at terminal T4, and zO is the impedance of the high frequency transmission line at terminal T5.) Therefore, in order to handle large power, it was necessary to make Vcc a dog. When the voltage used in other circuit parts is low, it is necessary to separately install a JC-DC converter and increase the voltage applied to terminal T4.
There are drawbacks such as the need for additional means to suppress the noise of the switching oscillator generated by the converter.

The present invention seeks to eliminate these drawbacks.

An embodiment of the present invention will be described below.

FIG. 2 shows one embodiment of the present invention. In FIG. 2, 21.22.63.24 are diodes, 26
, 26, 27-28 are capacitors, 29 is a directional coupler, and the others are the same as in FIG.

A part of the high frequency input power applied from the terminal T is taken out by the directional coupler 29 and converted into a negative voltage by a voltage doubler rectifier circuit consisting of diodes 21, 22 and capacitors 26, 27 or diodes 23, 24 and capacitors 26, 28. Take it out. The configuration is such that this voltage is superimposed on the terminal voltage of P2 or P3, respectively, and added to the terminal voltage of P2 or P3.

By doing this, for example, the potential of the terminal T5 changes to the potential of the terminal T4.
When terminal T6 is at the ground potential, the voltage at point 23 becomes the potential at terminal T4, and the sum of the terminal voltage at capacitor 28 is the voltage at diode 2. Although this is made conductive, a current flows, so if the charging current to the capacitor 28 is small, the added voltage will be extremely small. Therefore, approximately the same voltage as the terminal T4 is applied to the 21st point. On the other hand, terminal P2
Since the voltage is almost zero and the diode 1 is cut off, no current flows and the voltage across the capacitor 270 has a sufficiently large value. Therefore, the diode 1 is biased in the reverse direction with a voltage obtained by adding a voltage obtained by rectifying a part of the input high frequency in addition to the voltage at the terminal T4, so that even large input power can be cut off.

Since this reverse voltage is obtained by detecting a portion of the input high-frequency power, the capacitor required for rectification is small, making it compact, and there is no risk of new spurious generation.

Note that it is also possible to rectify a part of the input power to the terminal T and use it as a power source for the terminal T4 having the configuration shown in FIG.

As explained above, Equation 1 The present invention rectifies a part of the high frequency input power and uses it as part of the bias of the high frequency switch, so it not only becomes possible to switch large input signals, but also allows high voltage Since no other source is required to obtain the signal, and there is no risk of generating unnecessary spurious signals, the device is simple and has great industrial value.

[Brief explanation of drawings]

Fig. 1 is an electrical wiring diagram of a conventional frequency switch, and Fig. 2 is an electrical wiring diagram of a high frequency switch according to an embodiment of the present invention. 1.2 Diode, 3, 4 ...... Transistor, T5. T6... Control signal input terminal, 21-24... Diode, 26-28
······condenser. Part III

Claims (1)

[Claims] It includes a high-frequency switching element for inputting, switching and outputting high-frequency power, and a control transistor for switching the high-frequency switching element, and is configured to control the control transistor by an external control signal. A high-frequency switch 0 extracts a part of the high-frequency input and superimposes the detected voltage on the bias circuit of the control transistor.