SU997230A1 - Two-stage active band-pass filter - Google Patents

Description

The invention relates to electronics and can be used in frequency selection devices. A two-tier bandpass filter is known, containing two differential transformers and piezoelectric resonators Cl incorporated on its shoulders. The disadvantage of this filter is a low coefficient, which is associated with a significant level of insertion loss. The closest technical solution to the proposed is a two-link active band-pass filter, containing two frequency-selective two-port devices connected in parallel in the first link and connected to the upper potential terminal, two frequency-selective two-pole switches connected in parallel in the second link, five auxiliary two-pole, two of which have a negative. impedance, potential output terminal and common bus. In this filter there is an operational amplifier in each link, on the opposite phase shoulders of which there are part-selective two-terminal circuits. The potential output terminal is connected to the output of the amplifier of the second link 2}. This filter is characterized by low selectivity, which is connected, in 6СHOBHOMj with not enough blues working attenuation outside the passband, equal to the sum of the working attenuations of the star | Niev. In addition, the disadvantage of this filter is the impossibility of operating in a mode with a change in the direction of signal transmission. The purpose of the invention is to increase the number of beats. corrective and and ensuring the reversibility of the transfer, d {vuhvlennogo; active polo filter. The goal is achieved by the fact that in the dyuhzaennrm active bandpass filter, Keeping two frequency and two-port bipolar networks connected in parallel in the first wiener and connected to the input potential semlema, two frequency-selective two-terminal networks connected in parallel on the second, five bipolar networks, two groups of two-terminal two-terminal, connected in parallel on the second, five bipolar networks, and two numbers of two-terminal two-terminal, connected in parallel on the second the potential output terminal and the common bus, the frequency of the two-terminal pen Even two are connected in pairs in series with the frequency-selective two-terminal in The second link, between the common conclusions of series-connected two-terminal circuits, includes three series-connected auxiliary two-pole ports, with an average between the conclusions of the middle one and the common bus. Two-terminal networks with negative impedance are used, and the potential output terminal is connected to two frequencies by two-pole selective two-pole devices ...

FIG. 1 shows o6jo6tneHHaH schemes of the proposed filter; 2, an example of a specific implementation of the scheme.

Frequency zabiratelny dvukhpolzosniki 1 Z}. in each of the links, they are connected in parallel and connected to the input potential terminal 1 (in the first link) and to the output potential signal 2 (in the second link). Each of the four two-terminal Z, Zj are connected in pairs in series. Two-port Z, connected to a common bus, have a negative impedance. Two-terminal Z-j and 2Z auxiliary. Two-terminal Z can be implemented as a negative resistance converter.

The circuit shown in Fig. 2 is a particular case of the proposed circuit no. Where piezoelectric resonators 3-6 with parallel additional capacitors 7-10 are used as a two-terminal Z and Z 2. The negative impedances here are implemented according to the scheme on the operational amplifiers 11 and 12. In general, this scheme is a scheme of the active narrow-band piezoelectric filter, identical in its characteristics to the two-link filter, the link of which is assembled along the bridge circuit, and the piezrelectro primary resonator and capacitor.

When applied to terminal 1, terminal 2 emits a signal in a narrow frequency band outside which the signal is significantly attenuated. The signal can also be applied to terminal 2, i.e. The filter has the property of reversibility of converting an SHH ae @ Che§a §1u | silya FILTRE outside li @ fl @ q | i iii yQ {$ ai HS without further than the sum of workers

links. This is due to the possibility of two-way signal passing through the links of the filter, and as a result, the appearance of links at the junction of the links.

The proposed filter is compared with the known, has a high selectivity and provides signal transmission in both directions.

Claims (2)

Invention Formula A two-tier active bandpass filter containing two frequency-selective two-pole devices connected in parallel in the first link and connected to an input potential terminal, two frequency-selective poles connected in parallel in the second link, five auxiliary two-terminals, two of which have negative impedance, an output potential terminal and a common bus characterized in that, in order to increase the selectivity and ensure the reversibility of transmission, the frequency-selective two-pole network of the first link is connected in pairs in series with the frequency-selective two-terminal of the second link, between the common conclusions of the serially-connected frequency-selective two-terminal networks include three series-connected auxiliary bipolar nickname, while between the conclusions of the average of them and the common bus included two kickers with a negative. .impedance4, and the output potential of the terminal cor is united with two frequency selective two-terminal of the second link. Sources of information taken into account in the examination 41. Poilov R.P.Raschet polynomial differential-power piezo 45 electric filters on the operating parameter 1M. - Questions of radio electronics. Seri obshchetechnicheska, 1968, issue 13, p.28-29. 2. Bolotuk h.A, Active quartz 50 fnpgra on operational amplifiers. Radiopribrstroenie and Shklelektrnika, 1975, v.4, p.14-19 (prototype).