Patent Application
20070279009
As shown in
Traveling-wave tube 1 has a structure identical to the traveling-wave tube shown in
As shown in
Rectifying circuit 102 comprises a plurality of full-wave rectifying circuits, each made up of four bridge-connected diodes, connected in series with each other through capacitors. In
As shown in
Transistor Q5 has a collector connected to the base of transistor Q4 through resistor R24. The base of transistor Q5 is supplied with an output signal from comparator CMP. The output voltage of series regulator 103 is applied to the emitter of transistor Q5.
The output voltage of series regulator 103 is divided by resistors R31, R32. The divided voltage is compared with a predetermined constant reference voltage Eref by comparator CMP, which turns on or off transistor Q5 depending on the comparison result. According to the illustrated arrangement of series regulator 103, the current supplied to the base of transistor Q4 is controlled to equalize the divided voltage that is output from the junction between resistors R31, R32 to reference voltage Eref. In other words, the current supplied to the base of transistor Q4 is controlled such that series regulator 103 will output a desired constant voltage.
In power supply apparatus 100 shown in
As shown in
When charging bypass circuit 106 is turned on, electric charges are supplied from rectifying circuit 102 to capacitor bank 104, not through transistors Q1 through Q4 of series regulator 103, but through charging bypass circuit 106 connected parallel to transistors Q1 through Q4, thereby charging capacitor bank 104. At this time, since electric charges are supplied to capacitor bank 104 through single bypass transistor 111, capacitor bank 104 is charged more quickly than would a conventional power supply apparatus which would charge capacitor bank 104 through transistors Q1 through Q4. Therefore, the time required for helix voltage Ehel, that has dropped due to a load variation, to become stabilized at the original voltage is shortened.
As shown in
Charging bypass control circuit 108 applies a charging bypass circuit drive signal to turn on charging bypass circuit 106 when the load abruptly varies due to pulsed operation of traveling-wave tube 1 and the helix voltage Ehel drops. Charging bypass control circuit 108 turns off charging bypass circuit 106 when the power supply voltage (helix voltage Ehel) output from power supply apparatus 100 exceeds the predetermined voltage value as detected by overvoltage comparing circuit 107.
Charging bypass control circuit 108 may be implemented as a logic circuit comprising a combination of various logic gates or a driver circuit for driving bypass transistor 111 of charging bypass circuit 106.
In the present embodiment, charging bypass control circuit 108 detects a drop of the helix voltage Ehel using a pulsed signal (anode pulse input signal), which is the same as the drive signal for anode switch 112, output from anode switch control circuit 109, and controls charging bypass circuit 106. However, charging bypass control circuit 108 is not limited to the circuit arrangement for controlling charging bypass circuit 106 using the anode pulse input signal, but may control charging bypass circuit 106 using a detected value of the helix voltage Ehel that is supplied to traveling-wave tube 1. If charging bypass control circuit 108 controls charging bypass circuit 106 using a detected value of the helix voltage Ehel, then power supply apparatus 100 may have a voltage detecting circuit for detecting the helix voltage Ehel, and may turn on charging bypass circuit 106 if the voltage detecting circuit detects a drop of the helix voltage Ehel and turn off charging bypass circuit 106 if overvoltage comparing circuit 107 detects when the helix voltage Ehel exceeds the predetermined voltage value.
Operation of power supply apparatus 100 shown in
Specifically, operation of power supply apparatus 100, at the time that traveling-wave tube 1 shown in
When anode switch control circuit 109 shown in
As shown in
When the output signal from anode switch circuit 109 changes and anode switch 112 is turned off, the anode voltage Ea stops being supplied to the anode electrode of traveling-wave tube 1, and the helix current also stops flowing.
As shown in
Charging bypass control circuit 108 outputs the charging bypass circuit drive signal to turn on charging bypass circuit 106 in synchronism with the switching of the anode pulse input signal from the high level to the low level. Charging bypass circuit 106 turns on bypass transistor 111 to render it conductive based on the charging bypass circuit drive signal. When bypass transistor 111 is turned on, the input terminal (connected to rectifying circuit 102) of series regulator 103 supplies electric charges through charging bypass circuit 106 to capacitor bank 104, charging capacitor bank 104 to increase the helix voltage Ehel. At this time, since the electric charges are supplied, not through transistors Q1 through Q4 of series regulator 103, but through single bypass transistor 111, capacitor bank 104 is charged more quickly than with the conventional power supply apparatus, as shown in
When the helix voltage Ehel increases beyond the predetermined voltage value, overvoltage comparing circuit 107 outputs the helix overvoltage comparison signal to charging bypass control signal 108.
When charging bypass control signal 108 receives the helix overvoltage comparison signal, charging bypass control signal 108 changes the charging bypass circuit drive signal to the low level to turn off charging bypass circuit 106. Bypass transistor 111 is turned off by the charging bypass circuit drive signal, and hence charging bypass circuit 106 is rendered nonconductive, thus stopping charging capacitor bank 104. As a result, the power supply voltage (helix voltage Ehel) output from power supply apparatus 100 stops increasing and becomes stable.
In the above description, charging bypass circuit 106 is turned on in synchronism with the anode pulse input signal changing from the high level to the low level, and charging bypass circuit 106 is turned off in synchronism with the helix overvoltage comparison signal being output. However, the charging bypass circuit drive signal generated in synchronism with the anode pulse input signal that changes from the high level to the low level may be a pulse (one-shot trigger) signal having a preset time duration. Even if such a one-shot trigger signal is employed as the charging bypass circuit drive signal, it should preferably be combined with the control process for turning off charging bypass circuit 106 when the helix voltage Ehel exceeds the predetermined voltage value.
According to the present invention, when the power supply voltage drops, capacitor 104 is quickly charged through charging bypass circuit 106, and when the power supply voltage exceeds the predetermined voltage value, capacitor 104 stops being charged through charging bypass circuit 106.
Therefore, a variation in the power supply voltage (helix voltage Ehel) due to a variation in the load can be reduced without the need for increasing the capacitance of capacitor bank 104.
Therefore, the high-frequency circuit system is capable of reducing a variation in the power supply voltage even when a pulsed voltage is applied to the anode electrode to drive traveling-wave tube 1 in a pulsed mode.
Inasmuch as the capacitance of capacitor bank 104 for reducing a variation in the power supply voltage can be reduced, it is possible to reduce the size of power supply apparatus 100.
In the above embodiment, the power supply apparatus and the high-frequency circuit system have been described with respect to the example wherein the power supply apparatus that supplies the power supply voltage (helix voltage Ehel) is provided between the cathode electrode and the helix of traveling-wave tube 1 shown in
While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-151983 | May 2006 | JP | national |
