JPH0153922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high frequency switching circuit that performs high-speed switching of high frequencies using semiconductors and hybrids.

[Prior art]

A conventional circuit of this type is shown in FIG. In the figure, 1 is an antenna terminal for inputting high-frequency signals, 2 is a transmitter terminal for inputting high-frequency high power, 3 is a receiver terminal for outputting high-frequency signals, and 4 is a transmitter terminal for inputting high-frequency signals from antenna terminal 1. 2
Or 90° hybrid used to switch to receiver terminal 3, 5 (5a, 5b) is a PIN diode to short the two terminals of 90° hybrid 4, 6 is to turn on (short circuit) PIN diode 5. 7 is a positive power supply terminal that supplies positive power to the bias generation circuit 6; 8 is a control input terminal that controls the bias current of the bias generation circuit 6; 9 is the charge of the PIN diode 5; 10 is a negative power supply terminal for supplying negative power to semiconductor switch 9 to discharge the charge of PIN diode 5; 11 is a control input terminal for controlling semiconductor switch 9; 12 is a termination resistor for terminating one terminal of the 90° hybrid 4.

Next, the operation will be explained.

First, when connecting the antenna terminal 1 and the transmitter terminal 2, an "H"("L") level control signal is input to the control input terminal 8. Then, the bias generation circuit 6 uses the power supplied from the positive power supply terminal 7 to generate a bias to turn on (short-circuit) the PIN diode 5. As a result, the PIN diode 5 is turned ON, the two terminals of the 90° hybrid 4 are short-circuited, and the antenna terminal 1 and the transmitter terminal 2 are connected. Also, at this time, the receiver terminal 3 is connected to the terminal resistor 1.
Connected to 2.

Next, when connecting the antenna terminal 1 and the receiver terminal 3, a control signal of the opposite level to the above, that is, the "L"("H") level is input from the control input terminal 8. Then, the bias applied from the bias generation circuit 6 to the PIN diode 5 is eliminated. Further, at the same time as the above control signal is applied, a signal for controlling the semiconductor switch 9 is also input to the discharge control input terminal 11, and the negative power supplied from the negative power supply terminal 10 is accumulated in the PIN diode 5. The charge is rapidly discharged. When the charge on the PIN diode 5 disappears, the PIN diode 5 becomes OFF (open), and the antenna terminal 1 and the receiver terminal 3 are connected. Further, at this time, the transmitter terminal 2 is connected to the terminating resistor 12.

Circuit switching is performed in this way,
Now, if the charge in the PIN diode 5 is not rapidly discharged by the semiconductor switch 9, the charge in the PIN diode 5 will be discharged due to leakage current, and the discharge will take time. . As a result, the switching time between the antenna terminal 1 and the transmitter terminal 2 or receiver terminal 3 becomes longer.

As described above, conventional high frequency switching circuits have the disadvantage that in order to switch high frequency and high power at high speed, a negative power source for discharging is required in addition to a positive power source for biasing the PIN diode.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by discharging the charge accumulated in the PIN diode by switching the capacitor, it eliminates the need for a negative power supply for discharging. It is an object of the present invention to provide a high frequency switching circuit that can switch between high frequency and high power at high speed.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts. 13a and 13b are discharge capacitors for discharging the charges accumulated in the PIN diodes 5a and 5b, respectively;
One ends of PIN diodes 5a and 13b are connected to the anode sides of the PIN diodes 5a and 5b, respectively, and the other ends are connected to the semiconductor switch 9. This semiconductor switch 9 is controlled by a discharge control signal sent to a terminal 11, and connects the other ends of the capacitors 13a and 13b to a positive power source or ground.

Next, the operation will be explained.

When connecting the antenna terminal 1 and the transmitter terminal 2, if a control signal is input to the control input terminal 8 as in the conventional case, the bias generation circuit 6 receives the control signal and outputs the power supplied from the positive power supply terminal 7. using PIN
A bias is generated to turn on (short-circuit) the diodes 5a and 5b. As a result, the PIN diodes 5a and 5b are turned on, the two terminals of the 90° hybrid 4 are short-circuited, and the antenna terminal 1 and the transmitter terminal 2 are connected. Further, at this time, the receiver terminal 3 is connected to the terminating resistor 12. Here, when the PIN diode 5 is ON, the semiconductor switch 9 is connected to the positive power supply terminal 7 side as shown in FIG. 2, and therefore the discharging capacitor 13 is charged by the positive power supply. .

Next, when connecting the antenna terminal 1 and the receiver terminal 3, a control signal having a level opposite to that described above is input to the input terminal 8. Then, bias generation circuit 6
The bias applied to the PIN diode 5 disappears. At the same time as the above control signal is applied, a signal for controlling the semiconductor switch 9 is also input to the discharge control input terminal 11, and the semiconductor switch 9 is switched to ground one end of the discharge capacitor 13. When one end of the discharging capacitor 13 is grounded, the charge stored in the capacitor 13 is
Since the polarity is opposite to that of the charge stored in the PIN diode 5, the charge in the PIN diode 5 is discharged by the discharge capacitor 13. This PIN
When the charge in the diode 5 disappears, the PIN diode 5 becomes OFF (open), and the antenna terminal 1 and the receiver terminal 3 are connected. Further, at this time, the transmitter terminal 2 is connected to the terminating resistor 12.

In this embodiment device, the PIN diode 5
Since the accumulated charge is discharged by the capacitor 13 and the semiconductor switch 9 that switches it, the negative power supply device in the conventional device can be omitted, and the device can be made simple and inexpensive.

[Effects of the Invention] As described above, according to the present invention, the accumulated charge in the PIN diode is discharged by switching the capacitor, so high frequency and high power can be generated with a simple circuit configuration without using a negative power supply device. This has the effect of allowing high-speed switching.

[Brief explanation of drawings]

Figure 1 shows a conventional high frequency switching circuit, Figure 2 shows a conventional high frequency switching circuit.
The figure is a schematic configuration diagram of a high frequency switching circuit according to an embodiment of the present invention. 4... 90° hybrid, 5... PIN diode, 6... Bias generation circuit, 7... Positive power supply terminal, 8... Control input terminal, 9... Semiconductor switch, 11... Discharge control input terminal, 13 ...discharge capacitor. In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A device comprising two cascade-connected hybrids and two PIN diodes whose anodes are connected to two connection points between the hybrids and whose cathodes are grounded, and which turns both PIN diodes on and off. In a high frequency switching circuit that switches high frequency and high power using a high frequency switching circuit, a bias generating circuit generates a bias current to turn on both of the above two PIN diodes in response to an external control signal, and a positive power supply is supplied to the bias generating circuit. A positive power supply, two capacitors with one end connected to the anode side of the above two PIN diodes, and depending on the above external control signal, connect the other ends of the above capacitor to either the same positive power supply as the above positive power supply or the ground. A high frequency switching circuit comprising: a semiconductor switch connected to one of the PIN diodes to keep both of the two PIN diodes in the ON state or to turn them OFF.