JPH04256202A - Diode phase shifter - Google Patents

Abstract

PURPOSE:To set passing losses when a bias is on/off to be equal as a diode phase shifter by setting the absolute values of reflection coefficients when the bias is on/off to be equal. CONSTITUTION:Adjustment circuits including resistances 2A and 2B are connected in parallel to two PIN diodes 20 and 21. The resistances 2A and 2B of the adjustment circuits are adjusted so that the reflection coefficients of respective PIN diodes are equal in correspondence with the on/off of a bias supply switch 24 for the PIN diode 21.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective diode phase shifter used in the microwave band.

0002

2. Description of the Related Art A conventional diode phase shifter, as shown in FIG. 3, includes a microwave input 11, DC blocking capacitors 13 and 14, and an output 12 that outputs a phase-shifted microwave as a reflected wave, which will be described later. , microwave from input 11 to 2
A 90 degree hybrid that branches and outputs two waves with a phase difference of 90 degrees from each other, combines the two reflected waves described later, and outputs one reflected wave as an output 12, strip lines 16 to 19 for microwave transmission; PIN for macrowave phase shift
It blocks high frequencies and is composed of diodes 20, 21, an inductance 23A, and a capacitor 23B, and includes a DC bias supply low-pass filter 22, a bias voltage on/off switch 24, and a bias DC power source 25.

Next, the operation of the conventional example will be explained. The microwave inputted from the input 11 is phase-shifted by 90 degrees and branched into two, and is connected to each strip line 16, 18 and 17, 19.
Supplied via the PIN diode. On the other hand, the bias voltage is applied to the PIN diode 2 by turning on and off the switch 24.
1 or left open, changing the phase of the reflection coefficient of the PIN diode 21. This change in impedance of the reflection coefficient is shown in locus A of the Smith chart in FIG. That is, the point is 27 when the bias is on, and the point is 26 when the bias is off, changing the phase. but,
As can be seen from the B line corresponding to the reflection coefficient in Figure 2,
The reflection coefficient at point 27 was smaller than that at point 26, and as a result, the loss at point 27 was greater than at point 26.

0004

[Problems to be Solved by the Invention] In the conventional diode phase shifter described above, as can be seen from line B of the Smith chart in FIG. When used, there was a drawback that the passage loss when the bias was on was larger than when the bias was off, resulting in a difference in the passage loss when the bias was on and when the bias was off.

[0005]

[Means for Solving the Problems] The diode phase shifter of the present invention includes a 90-degree hybrid having four terminals, and a 90-degree hybrid having four terminals.
a PIN diode connected to each of the two terminals of the 0 degree hybrid via a strip line;
a switch that applies a bias voltage on and off to the PIN diode; and a diode phase shifter that turns on and off the switch to combine and output reflected waves from the PIN diode from one terminal of the 90-degree hybrid. An adjustment circuit including a resistor is connected in parallel to each of the PIN diodes, and the resistance of the adjustment circuit is adjusted in response to on/off of the switch so as to equalize the reflection coefficient of each PIN diode.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a characteristic diagram common to this embodiment and the conventional example. Figure 1
In this embodiment, the same reference numerals as in the conventional example of FIG. 3 have the same structure and function. In other words, in this embodiment, a combination of wires 1A and 3A, a resistor 3A, and a DC blocking capacitor 4A are connected in parallel with the PIN diodes 20 and 21, respectively, and the wire 1 serves as an inductance.
B, 3B, a combination of resistor 3B, and capacitor 4B are connected. Here, the resistors 2A and 2B are selected while looking at the characteristics described later.

Next, the operation of this embodiment will be explained with reference to the Smith chart shown in FIG. The reflection coefficient of a single PIN diode is at point 26 when the bias is off, as described above. When the high ass is turned off, it moves to point 27, but the absolute value of point 27 has a smaller reflection coefficient than point 26. Here, when resistors 2A and 2B are connected in parallel, point 26 moves to point 28 while point 27 remains almost unchanged. So point 27 and point 2
The resistors 2A and 2 are connected so that the absolute values of the reflection coefficients of 8 are equal.
Select the value of B to equalize the amount of reflection. As a result, the passage loss from input 1 to output 2 in FIG. 1 can be made equal when the bias is on and when the bias is off.

[0009]

[Effects of the Invention] As explained above, the present invention enables each PIN
By connecting a resistor in parallel to the diode, the absolute value of the reflection coefficient when the bias is on and when the bias is off is made equal, and as a diode phase shifter, it is possible to equalize the passage loss when the bias is on and when the bias is off.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a diode phase shifter according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram on a Smith chart common to the present embodiment and the conventional example.

FIG. 3 is a block diagram of a conventional diode phase shifter.

[Explanation of symbols]

1A, 1B, 3A, 3B Wire 2A, 2B
Resistance 4A, 4B Capacitor 11 Input 12 Output 13, 14, 23B Capacitor 16 to 19
Strip line 20, 21 PIN diode 22 Low pass filter 23A Inductance 24 Bias switch 25 DC power supply

Claims (2)

[Claims] Claim 1: A 90-degree hybrid having four terminals, a PIN diode connected to each of the two terminals of the 90-degree hybrid via a strip line, and a bias voltage for turning on and off the PIN diode. a diode phase shifter that combines and outputs reflected waves from the PIN diode from one terminal of the 90-degree hybrid by turning on and off the switch; A diode phase shifter, characterized in that an adjustment circuit including a resistor is connected to the switch, and the resistance of the adjustment circuit is adjusted so as to equalize the reflection coefficient of each PIN diode in response to the on/off of the switch. 2. The adjustment circuit comprises a first wire having an inductance connected to a PIN diode, a resistor connected to the first wire, and a second wire connected to the other end of the resistor. , and a DC blocking capacitor connected to the second wire.