JPS5818004B2 - Band “ro” wave device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a band p-wave transducer, and more particularly to a band p-wave transducer with a wide passband width.

FIG. 1 is an electrical circuit diagram showing an example of a bandpass wave transducer which is the background of the present invention.

The signal given from the input side is transmitted through the double-tuned wideband transformer T.
given to.

Then, out of the output of this transformer T, the unnecessary signals are transferred to trap circuits TRP 1 (f 2 ) and TRP2.
(f 3 ), the characteristics shown in FIG. 2 are obtained.

In addition, the double-tuned broadband transformer T and the trap circuit TRP1
A resistor R is inserted between the two to prevent frequency shift due to mutual interference.

In the bandpass offshore wave device as shown in Fig. 1, 2
two trap circuits TRP1. TRP2 constitutes a parallel resonant circuit, and a local maximum point of impedance occurs within its passband (frequency f2 to f3).

Therefore, even though the double-tuned transformer T is used to obtain wideband pass characteristics, the bandwidth cannot be widened, as shown in FIG. 2.

Therefore, even if a certain width of passband width is required at the peak level, this requirement cannot be satisfied.

Therefore, the main object of the present invention is to provide a band F-wave converter with a wider passband width in a simple circuit configuration. The impedance minimum point is further obtained near the tuning frequency of the single tuning transformer by outputting it through one circuit of two parallel LCC troughs connected in cascade, and by appropriately selecting the constants of these two trap circuits. , forming a staggered tuning circuit.

The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 3 is an electrical circuit diagram showing one embodiment of the present invention.

In the configuration, T' is a singly tuned transformer whose outputs are connected to parallel trap circuits TRP1' and TRP
2' series circuit to the output side.

In the above configuration, the tuning frequency of the single tuning transformer T' is fl, and the trap circuits TRP1' and TRP
2' resonance frequencies are shown in FIG. 4 as f2 and f3.

That is, the parallel trap circuits TRP1' and T
RP2' creates two attenuation poles (f2 and f3
) and a valley with an impedance minimum point (f4) in the middle thereof.A staggered tuning circuit is formed by shifting the resonant frequency f1 of the single tuning transformer T' and the impedance minimum point frequency f4. Widen the width.

Note that when the impedance on the output side is low, it is desirable to connect the trap circuits TRP 1' and TRP 2' as shown in Fig. 3, which provides large attenuation at frequencies f2 and f3, and A gentle peak can be seen near f4.

The frequency f4 is given by the following equation (1).

The ratio of capacitors C1 and C2 included in each of trap circuits TRP 1' and TRP 2' is expressed as C
If 2/CI=, the above equation (1) can be written as the following equation (2).

Here, the frequencies f2 and f3 are the trap circuit TRP.
It is a constant determined by the coil L1 and capacitor C1 of the trap circuit TRP2' and the coil L2 and capacitor C2 of the trap circuit TRP2', and the frequency f4 is determined by the constant, that is, the ratio of the capacitor C2 and the capacitor C1.

In a specific experimental example, the capacitor C1 was 39 pF, the capacitor C2 was 33 pF, the turns ratio of the single tuning transformer T' was 0.4, and the tuning capacitance was 200 pF.

At this time, the center frequency is 5.06 MHz. 3dB bandwidth is 500KHz, 49dB attenuation at frequency f2 = 3.81 MHz, frequency f3 = 6.31 MHz
An attenuation of 53 dB and an in-passband ripple of 0.6 dB were obtained.

As described above, according to the present invention, a wide passband width and a larger amount of attenuation can be obtained with a simple circuit without using a complex and troublesome double-tuned transformer.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing an example of a bandpass wave transducer which is the background of the present invention. FIG. 2 is a graph showing the characteristics of the circuit shown in FIG. FIG. 3 is an electrical circuit diagram showing one embodiment of the present invention. FIG. 4 is a graph showing the characteristics of the circuit of FIG. In the figure, T' is a single tuning transformer, TRP1' and T
RP2' is a trap circuit, Ll and L2 are coils, C
1 and C2 indicate capacitors.

Claims (1)

[Scope of Claims] 1. A tuned circuit that resonates at a frequency f1, a first parallel resonant circuit that includes a parallel circuit of a first capacitor and a first coil, and that resonates at a frequency f2 upon receiving the output of the tuned circuit; a second parallel resonant circuit consisting of a capacitor and a second coil and resonating at a frequency f3 in response to the output of the first resonant circuit, the first parallel resonant circuit and the second parallel resonant circuit having a frequency A series resonant circuit that resonates at f4 is configured, and the frequency f4 is selected in the vicinity of the frequency fl and within the band of frequencies f2 and f3 by the ratio of the first capacitor and the second capacitor. vessel.