JPS6040211B2 - dividing network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dividing network that divides an input signal into multiple frequency bands.

As shown in FIG. 1, conventional dividing networks have been known to consist of a low-pass filter, a band-pass filter, and a high-pass filter each consisting of a coil, a capacitor, a resistor, and the like.

In this method, frequency division is performed by matching the cutoff frequencies of two filters that share adjacent frequency bands with respect to one crossover frequency. However, there are errors in the values of the coils, capacitors, resistors, etc. that make up the filter, and it is difficult to match the cutoff frequency exactly as shown in Figure 2. The cutoff frequency and crossover frequency often did not match. or,
When making the crossover frequency continuously variable, the cutoff frequencies of the two filters must be changed independently, which not only makes it difficult to match the cutoff frequencies of the two filters, but also affects the attenuation characteristics. The disadvantage was that matching was extremely difficult and distortion occurred near the crossover frequency. The purpose of this invention is to accurately set the crossover frequency using the cutoff frequency of one filter, and to properly match the attenuation characteristics around the crossover frequency, thereby reducing distortion around the crossover frequency. It is an object of the present invention to provide a dividing network that minimizes distortion near the crossover frequency even when the cutoff frequency is made continuously variable.

The present invention will be explained below with reference to FIG. 4 showing an embodiment.

This example concerns a dividing network that divides into three frequency bands.

Reference numeral 1 denotes a high-pass filter consisting of resistors R1 and R2, capacitors C1 and C2, and an oven amplifier 01, and set to a cutoff frequency fcl.

2 consists of resistors R3 and R4, capacitors C3 and C4, and an oven amplifier 02, and the cutoff frequency is set to 2.

It is a pass filter. 3 is resistance R5, R6, R7
, R8, and an OBE amplifier 03.

However, it is assumed that 1>fc2. The dividing network input terminal Ti is the input terminal T of the high pass filter.
1. The input terminal T2 of the low-pass filter is connected to the subtraction input terminal T3 of the subtraction circuit 3.

/・The output end of the pass filter is attenuator A
It is connected to the Takagi output terminal Th via I and also to the subtraction input terminal T4 of the subtraction circuit 3. The output terminal of the low-pass filter 2 is connected to the low-frequency output terminal TI via an attenuator A2, and is also input to the subtraction input terminal T5 of the subtraction circuit 3 via a switch S. The output terminal of the subtraction circuit 3 is connected to the Nakagusuku output terminal Tm. The operation of this circuit will be explained.

When the switch S is closed, the input signal from Ti (hereinafter referred to as the full-band input signal) is input to the input terminal T1 of the high-pass filter 1 and the input terminal T2 of the low-pass filter 1.
is input to the subtracted input terminal T3 of the subtraction circuit 3.

The high-pass filter 1 outputs a signal of one or more frequency bands at the cutoff frequency among the input signals of all the bands from the high-frequency output terminal Th via the attenuator AI, and also outputs the signal from the high-frequency output terminal Th through the attenuator AI. Input to T4.
The low-pass filter 2 outputs the signal in the frequency band below the cutoff frequency fc2 among the input full-band signals through the attenuator A2 from the low-frequency output terminal TI, and also outputs it from the subtraction input terminal of the subtraction circuit 3. Input to T5. In the subtraction circuit 3, the output signal of the high-pass filter 1, which is input to the subtraction input terminal T4, and the output signal of the low-pass filter 2, which is input to the subtraction input terminal T5, are obtained from the full-band input signal input to the input terminal T3 to be subtracted. By subtracting , a signal having a frequency band lower than 1 to the cutoff frequency of the low-pass filter and higher than the cutoff frequency fc2 of the low-pass filter is output from the mid-range output terminal Tm. As a result of the above, a high frequency band signal with a frequency higher than fCI is transmitted from the Takagi output terminal Th, and f is transmitted from the mid-range output terminal Tm.
A medium frequency band signal with a frequency of less than cl or more than fc2 is output from the low frequency output terminal TI, and a low frequency band signal with a frequency of less than 2 is output from the low frequency output terminal TI.

When the switch S is open, there is no input from the subtraction terminal input T5, and in the subtraction circuit 3, there is no input from the subtraction input terminal T5 from the full-band input signal input to the subtraction input terminal T3.
By subtracting the output signal of the pass filter 1 which is input to 4, a frequency band signal below the cutoff frequency fcl of the pass filter 1 is output.

Therefore, by opening and closing the switch S, the frequency band can be easily divided into two or three divisions.

Furthermore, Ku. To make the cut-off frequency of the high-pass filter 1 or the low-pass filter 2 variable, it is sufficient to make the cut-off frequency of the high-pass filter 1 or the low-pass filter 2 variable, and there is no need to modify the subtraction circuit that outputs the medium-band signal. In the above embodiment, the circuit is divided into two and three, but multi-division is also possible by adding filters and subtraction circuits.

According to the present invention described above, since the crossover frequency is determined by the cutoff frequency of one filter, there is no inappropriate division near the crossover frequency, so distortion is small, and the divided band can be controlled with one switch. It is easy to change, and it is also easy to make the crossover frequency variable, so there is no increase in distortion.

The circuit of the present invention is also effective as an input signal dividing circuit for driving multiway speakers.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional dividing network, Figure 2 is a Bode diagram showing proper frequency division, Figure 3 is a Bode diagram showing improper frequency division, and Figure 4 is the invention of the present invention. It is a circuit diagram showing an example of. 1...High-pass filter, 2...Low-pass filter
, 3... Subtraction circuit. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A low-pass filter that outputs the low-frequency components of the input signal, and a high-pass filter that outputs the high-frequency components of the input signal.
a subtraction circuit that subtracts output signals of the low-pass filter and high-pass filter from an input signal and outputs the result independently of the output signal of the filter; and an output terminal of at least one of the filters and a subtraction input terminal of the subtraction circuit. 1. A dividing network comprising: a switch means provided between the subtracting circuit and the subtracting circuit;