SU1427579A1 - Wide-band switchable filter - Google Patents

Abstract

The invention relates to radio and provides increased selectivity and increased number of passbands. The wide-band switched filter contains N channels 1, each of which consists of three cross-section links (PZ) 2,3,4 and key 5. PZ 4 consists of an LC circuit and key 8. Each channel forms two

Description

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good bandwidths. To receive a signal in the first passband in the first channel 1, the switch 5 is opened, and the switch 8 is closed. At the same time, the PZ 2.3: the remaining channels 1 perform the role of notch filters. To receive a signal in the second passband in the first channel, key 8 is open, and

one

The invention relates to radio technology and is intended to be used as an input filter for radio receivers, as well as as an output filter for wideband transmitters.

The purpose of the invention is to increase the selectivity and increase the number of bandwidths.

Figure 1 shows a circuit diagram of a wide-range switched filter containing three channels (N "3); in fig. 2 is a circuit diagram of a third band link, made in the form of a parallel LC circuit.

The wideband switched filter (FIG. 1) contains N channels 1 (three channels are shown in FIG. 1), each of which consists of the first 2, second 3 and third 4 band links and a key 5, while the third band link 4 contains a coil 6 inductance and capacitor 7, forming a serial LC-circuit, as well as an additional key 8; the third band link 4 (figure 2) can be made in the form of a parallel LC-circuit 9 and two additional keys 10 and 11.

Wideband switched. The filter works as follows.

Each channel 1 forms two adjacent bandwidths. In the initial state, in all channels, the key 5 is closed, and the additional key 8 is open. To receive a signal in the first passband in the first channel 1, the key 5 is opened, and the additional key 8 is silenced. In this case, the first and second band links 2 and 3 of all

 To the working attenuation terminals, one more is added due to the inclusion of the PZ 4 LC circuit. 2 hp , 2 Il.

The remaining channels 1 play the role of notch circuits connected to the input and output of a wide-range switched filter. The poles of the working attenuation of these notch circuits lie on the frequency axis above the upper cut-off frequency of the first and second bandwidths.

To receive a signal in the second passband in the first channel, the additional key 8 is opened (the other keys are in the same state). To the existing poles of the working attenuation is added more. one attenuation pole due to the connection of a series LC circuit made up by the inductor 6 and the capacitor 7, the third band link 4 of the first channel 1

Similarly, a wideband switched filter operates in other bandwidths.

A parallel LC circuit (Fig. 2) containing additional keys 10 and 11 is also used as the third band band link 4 in Fig. 2. In this case, the operation of the wideband switched filter is similar to that described above, i.e. the order of operation of additional keys 8 and 10 is the same, and the key 11 is open. The peculiarity of the use of the parallel LC circuit 9 is the possibility of simultaneous operation in the first and second bandwidths, which is achieved when the additional key 11 is closed. Similarly, the additional keys 10 and 11 operate when receiving signals in other bandwidths.

Thus, in the proposed wide-range switched filter, the number of switchable passbands is doubled, while achieving an increase in selectivity by providing narrower passbands with the same number of reactive elements.

Claims (3)

 1. A wideband switched filter containing N channels, each of which contains three bandpass links, the inputs of the first and the outputs of the second bandwidth links are combined and are respectively the input and output of a wideband switched filter, while the output of the first polo-20 link in each channel is made in the video link in each channel through the de-parallel LC circuit, each key is connected to a common bus, the t-branch of which includes an additional Because in order to increase the selectivity and increase the number of passbands, in each channel the third band link is switched and the output of the first band link is connected to the input of the second band link, the junction point of which is connected to the common bus through the third band link. 2. Filter POP.1, characterized in that the third band link in each channel is implemented as a serial LC circuit, and the connection point of the inductor and the capacitor is connected via an additional switch to the common bus .. 3. Filter POP.1, characterized in that the third band pass key. FIG. 2