JPS62112401A - Higher harmonic elimination diode switch circuit - Google Patents

Abstract

PURPOSE:To enhance a higher harmonic suppressing wave without using a higher harmonic blocking filter by inserting a transmission line having an electric length of 1/4 wavelength in parallel with a signal output of a switching diode. CONSTITUTION:A bias current feedback circuit provided to the signal output of the switching diode 4 connected in series with the transmission line uses a transmission line 9 having an electric length of 1/4 wavelength whose end is grounded and a higher harmonic blocking chock coil 6 is used to the bias current supply side of the signal input side to constitute a bias current circuit. Further, the current of the bias current circuit is limited by inserting a current limit resistor to the bias current supply side of a conventional choke coil 6, the current limit resistor 8 is connected in parallel with a short-circuit capacitance element 7 and connected to the end of the transmission line and grounded so as to offer the same effect. Thus, the higher harmonic being the 2n times of order of the fundamental frequency is short-circuited and the higher harmonic components do not appear at the output side.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a switch circuit used in microwave equipment.

(Prior art and its problems) FIG. 4 shows an example of a conventional diode switch circuit. In the figure, 41 is a DC bias blocking capacitor on the input side, 42 is a DC bias blocking capacitor on the output side, 4
3 is a pin diode for parallel switching, 44 is a pin diode for series switching, 45 and 46 are R and F choke coils, 47 is a short-circuit capacitance element, and 48 is a current limiting resistor. In such a diode switch circuit, when a positive voltage is applied to the bias terminal, a forward bias is applied to the series diode 44 and the series diode 44 becomes conductive.

On the other hand, the parallel diode 43 becomes reverse biased and becomes non-conductive. In this state, the signal from the input terminal will appear at the output terminal. Next, when a negative voltage is applied to the bias terminal, the series diode 44 becomes reverse biased and becomes non-conducting, and the parallel diode 43 becomes forward biased and becomes conductive, so the signal at the input terminal does not appear at the output terminal. do not have. Therefore, such a circuit operates as a high frequency changeover switch by changing the polarity of the bias terminal.

By the way, diode elements are generally nonlinear, and when a large amplitude signal exceeding a linear region is applied, harmonic components are generated. When a high suppression ratio is required for such harmonic components, conventionally a harmonic rejection filter for removing the harmonic components is inserted on the output side of the switch circuit. However, this method has the disadvantage that the circuit becomes complicated and large.

(Means for Solving the Problems) The present invention provides a multi-diode circuit having a harmonic suppression function that eliminates the drawbacks of the prior art described above, and is connected in parallel to the signal output side of the switching diode. This is characterized by the insertion of a transmission line with an electrical length of the wavelength.

In the present invention, the bias current feedback circuit provided on the signal output side of the switching diode connected in series in the signal transmission line of the diode switch circuit is L/4.
A bias current circuit is constructed by using a transmission line with an electrical length equal to the wavelength and whose tip is grounded, and a high frequency blocking choke coil on the bias current supply side of one signal input side.

Current limiting of this bias current circuit is normally performed by inserting a current limiting resistor on the bias current supply side of the choke coil, but this current limiting resistor is connected in parallel with the short-circuiting capantance element and connected to the tip of the transmission line. The effect is the same even if it is connected and grounded.

The present invention will be explained below using examples. Figures 1 to 3
The figure shows an embodiment of the present invention, in which 1 is a DC bias blocking capacitor on the input side, 2 is a DC bias blocking capacitor on the output side, 3 is a parallel diode, 4 is a series diode,
5.6 is an RF choke coil, 7 is a short-circuiting capantance element, and up to this point the circuit is the same as the conventional circuit shown in FIG. Further, 8 is a current limiting resistor, 9.12 is a transmission line having an electrical length of wavelength (V4λ), 10 is a short-circuit capacitance element, and 11 is a transmission line having an electrical length of lump wavelength ('V8λ). This part is a feature of the present invention.

(Function and Effect) Fig. 1 shows a conventional circuit shown in Fig. 4 in which the R and F choke coils 45 are replaced with a transmission line 9 whose ends are short-circuited and have an electrical length equal to the rock wavelength. The harmonics of 2n times the fundamental frequency are short-circuited, and these harmonic components do not appear on the output side. Also, in this case, the reverse bias voltage of the parallel diode 3 is applied by the voltage drop of the series diode 4, so that the reverse bias voltage becomes shallower and the number of isolanes 3 decreases. Next, the second figure is 1/4
This is a circuit in which a current limiting resistor 8 and a short-circuit capacitance element are connected in parallel to the tip of a wavelength transmission line 9 and connected to ground. In this case, the voltage drop of the current limiting resistor 8 is
The isolane 3 link is improved because it is reverse biased. Furthermore, as shown in Figure 3, 1. Transmission lines with an electrical length of /8 wavelengths are connected to n terrace rows, and end-grounded transmission lines with an electrical length of 14 wavelengths are connected in parallel and grounded at both ends of these transmission lines and at the connection point. It is possible that

By employing such a circuit, further harmonic attenuation is possible.

The functions and effects have been explained above with reference to the embodiments, but in the present invention, 1. By connecting a transmission line with an electrical length of /4a in parallel to the output side, a signal with a predetermined fundamental frequency is guided as it is to the output terminal, and harmonics of 2n times the fundamental frequency are transmitted with the tip short-circuited. This bypass takes advantage of the fact that the in-beam interface of the line is short-circuited.

In addition, the transmission line and other parts of the high frequency removal diode switch circuit of the present invention can be connected to a printed circuit board.
If the tubular line is constructed, it is easy to design and manufacture a transmission line with a short-circuited end having an electrical length of 14 wavelengths, and also has the advantage that the conventionally used choke coil for blocking high frequencies can be omitted.

As described above, the present invention can not only remove harmonics caused by the nonlinearity of the diode, but also remove harmonics contained in the input signal at the same time.

[Brief explanation of drawings]

1 to 3 show an embodiment of the harmonic elimination diode switch circuit of the present invention, and FIG. 4 shows an example of a diode switch circuit according to the prior art. In the figure, 1.2 is a DC bias blocking capacitor, 3 is a parallel diode, 4 is a series diode, 5.6 is a choke coil, 7 is a short-circuit capacitance element, 8 is a current limiting resistor, and 9.12 is an electrical length of the theoretical wavelength. 1o is a short-circuit capacitance element, and 11 is a transmission line having an electrical length of the duck wavelength.

Claims (2)

[Claims] (1) In a diode switch circuit having a switching diode inserted in series in a transmission line, a bias current feedback circuit provided on the output side of the diode, and a bias current supply circuit provided on the input side of the diode, the Use bias current feedback circuit 1/1 of signal frequency
A harmonic elimination diode switch circuit comprising a short-circuited transmission line with a grounded end having an electrical length of four wavelengths. (2) A diode switch circuit having a switching diode inserted in series in a transmission line, a bias current feedback circuit provided on the output side of the diode, and a bias current supply circuit provided on the input side of the diode, The bias current feedback circuit is composed of a transmission line having an electrical length equal to the wavelength of the operating frequency, and a parallel circuit of a short-circuiting capacitance element and a current limiting resistor connected in series to the transmission line and having a grounded tip. Features a harmonic elimination diode switch circuit.