EP2702599A1

EP2702599A1 - Radio-frequency circuit assembly

Info

Publication number: EP2702599A1
Application number: EP11724458.2A
Authority: EP
Inventors: Genadij Skorobogatov; Tomas Cerniauskas
Original assignee: UAB "Terra"
Current assignee: UAB "Terra"
Priority date: 2011-04-29
Filing date: 2011-04-29
Publication date: 2014-03-05
Anticipated expiration: 2031-04-29
Also published as: EP2702599B1; WO2012146952A1

Abstract

The radio - frequency circuit assembly, suitable for the radio - frequency signals, has a radio- frequency signal input terminal (508) and a radio - frequency signal output terminal (509) for the radio - frequency signal transmission to the radio - frequency circuit, functioning in accordance with the commutation principle, and for the radio - frequency signal removal from the radio- frequency circuit accordingly; double-pole (SADP) multi- throw, of at least four commutation positions (501p-504p, etc.), slide switch (SA1); few commutated attenuator sets (502s -504s, etc.), constructed in the configuration 'Π 1, and one radio - frequency signal by-pass path (507), presented between the side contact terminals (SA1c) of the slide switch (SA1), from one side of the slide switch (SA1).

Description

RADIO-FREQUENCY CIRCUIT ASSEMBLY

Technical Field

The present invention pertains to the field of the radio-frequency communication and is related to the radio-frequency circuits that are commonly used in the passive and active broadband equipment which is assigned for the cable networks for television signals, sound signals and interactive services.

With the aim to effectively proceed to the use of a higher order radio-frequency circuits, i.e. the circuits with more commutation positions, able to control the level of radio-frequency attenuation, implemented in the double-pole multi-throw slide switch, covering now a more wide part of the frequency range which is assigned for CATV/MATV/SMATV cable television network systems and individual receiving systems, including the improvement of the radio-frequency characteristics in the lower-frequency part of this range, it is necessary to increase the integration of the available radio-frequency circuits, i.e. the solution is a compressed arrangement of the components. One of the constructive-topological schemotechnical solutions is our proposed constructive-topological arrangement of the components comprising the radio-frequency circuit, which was unknown and not in use before our invention in all passive and active broadband equipment of CATV/MATV/SMATV cable television network systems and individual receiving systems assigned for the cable networks for television signals, sound signals and interactive services for our application. When constructively-topologically combining mechanical slide switches, having more than three double-pole throws, i.e. DP4T, DP5T or higher order, with the radio-frequency circuit components assembly, positive effect is reached - the requirements of the IEC 60728 Standard, applied to the passive and active broadband equipment which is assigned for the cable networks for television signals, sound signals and interactive services are met in a much easier way.

Background Art

The cable television field is rapidly evolving and changing. It is well-known in the industry of electronics of the cable television that integration level in designing new printed circuit boards is constantly increasing. The increasing integration of the new printed circuit board designs and its modules provides for entering new markets and reducing expenses for the existing applications. Until now the switchable cable television circuits, such as the step attenuators or equalizers, were used only with the low-cost double-pole three-throw mechanical slide switches. Obviously, within the next following years the global market will be filled with unique, more powerful and innovative ideas, including new constructions of the mechanical slide switches supporting DP4T or greater configurations.

The word 'cable television' encompasses the hybrid fiber coaxial network system used nowadays for providing telecommunication services, voice, data, audio and video both broadcast and narrowcast. The hybrid fiber coaxial network system is an advanced cable television transmission system that uses the optical fiber cable for the head-end and feeder distribution system and coaxial cable for the customers end connection. Hybrid fiber coaxial is the second generation of the cable television systems.

The hybrid fiber coaxial network system distributes television signals received via the terrestrial and satellite antennas of CATV/MATV/SMATV cable television network system, which consists of the head-end equipment, distribution network and home network interface units. The head-end equipment receives information, such as terrestrial television (Master Antenna Television), analogue and digital satellite television (Satellite Master Antenna Television) signals, Internet packets and streaming media, and further delivers them to distribution network. Then the distribution network sends the signals to home network interface units which redistribute them via coaxial cables to home networks of residents. Nowadays, modern CATV/MATV/SMATV cable television network systems, including individual receiving systems, are routinely being built with an upper frequency limit of 862MHz and, in some exceptional cases, up to 1000MHz.

The International Standard IEC 60728 regulates CATV/MATV/SMATV cable television network system and individual receiving systems, including equipment and associated methods of measurement for head-end reception, processing and distribution of television signals, sound signals and associated data signals, and processing, interfacing and transmitting all kinds of signals for interactive services using all applicable transmission media. The IEC 60728-4 Standard covers the attenuators, equalizers and other devices of CATV/MATV/SMATV cable television network system and individual receiving systems, which according to the standard requirements must operate in the frequency range from 5MHz to 3000MHz.

With the bandwidth increased up to 1000MHz and higher it is becoming more difficult to maintain the correct hybrid fiber coaxial network system signal levels at the subscriber or end user. Many signals received by the terrestrial and satellite antennas will most probably fall into a wide variety of signal levels. In order to ensure the same picture quality on all television channels, the signals travelling over the hybrid fiber coaxial network system must be equalized to supply flat or equal signal levels to the subscribers. Therefore, the hybrid fiber coaxial network systems frequently require continuously or digitally changeable and parametrically controlled attenuators and equalizers for adjusting and monitoring the signal level.

Video signals are typically transmitted via coaxial cable with the characteristic impedance of 75 ohm. One of the most problematic issues related to the use of the coaxial cables is the occurring cable losses. Such losses negatively affect the information transmitted to the subscriber or end user. Coaxial cable attenuation depends on the cable length and frequency of the transmitted signal. Obviously, the longer the coaxial cable, the greater the loss. It is also known, that the loss depends on the frequency - it broadly rises with frequency, although the actual level of the loss does not linearly depend on the frequency. This effect may be referred to as the 'slope loss'. Any power lost in the coaxial cable will impair the performance of the system in which it is used. Therefore, such CATV/MATV/SMATV cable television network systems, including individual receiving systems, require correction or pre-correction equalizers to cancel the linear distortions caused by this tilt. Attenuators reduce all signals that pass through the cable television network system by the same amount. Attenuators and correction or pre-correction equalizers must be switchable so that the signals could be reduced in increments to the required signal level.

As it is well-known, there exist mechanical slide switches, having an assembly that slides from one position to another. Slide switches are defined by poles and throws. The poles refer to a number of the switch contact sets. The throws refer to a number of positions to which each pole is switched. Slide switch with two poles and four throws is commonly referred to as the double-pole four-throw DP4T slide switch. It contains two movable wipers that move in unison across two sets of terminals. The wipers are mechanically linked or ganged. Physical and electrical properties of the mechanical slide switches make them uniquely suitable for the radio-frequency signal switching applications. The cable television circuits, such as step attenuators or equalizers, used with the low-cost double-pole mechanical slide switches typically offer a cost-efficient solution comparing with the traditional adjustable attenuator or equalizer control circuits (see China Patent No.CN2473761, for example, where the high-frequency variable attenuator is proposed, which is a typical application in the cable television, and China Patent No.CN2901737, where the slope variable equalizer is proposed) and features an advanced design, providing many benefits compared to conventional control circuits. Slide switches do not require much space. Since they have no internal electronics, mechanical switches do not emit electromagnetic noise and are immune to such effects even when the signal levels are extremely high. Printed circuit board mounting, professional slide switches with vertical actuator having gold or silver plated terminal contacts with 'make-before-brake' terminal configuration, have electrical lifetime of several ten thousands of operations, while for the cable television application only several operations are required to obtain a necessary slide switch position which increases or decreases the necessary signal level for the cable television circuit. There are different terminal types for slide switches, for example, through hole and surface mounting. With regard to the construction materials, most slide switch bases and slide switch actuators are made of plastic, thermoplastic or metal. When mechanical slide switches are shifted, a virtually uninterrupted signal flow is guaranteed - multimedia services remain undisturbed, i.e. in mechanical slide switches with 'make-before-break' contacts, usually named as 'shorting', the normally open contact closes before the normally closed contact opens. This allows an overlapping functioning with the activation of one function before the interruption of the first one. The necessary attenuation and slope values can be set with a combination of several mechanical slide switches. All adjustments using mechanical slide switches can be carried out very easily. For example, the construction of the conventional mechanical slide switch is disclosed in US Patent No.US3987263. The above mentioned device provides a some special arrangement of slide switch contacts. The switching device prevents electrical coupling between terminal contacts, improves signal isolation, considerably suppresses unwanted radiation, improves impedance matching characteristic in the higher frequency bands, is cost-efficient to the manufacture and is highly reliable and dependable in operation. The next section will reveal how essential it is for our application. It is necessary for the cable television control circuits to have different arrangements of the slide switch contacts from the simple on/off to the double-pole multi-throw slide switches.

It is well-known in the art that variable attenuation can be provided in discrete steps by a switched attenuator. The step attenuators are available in various attenuation levels and can be used to provide attenuation values ranging from 1dB to 120dB or more, when the signal attenuation is controlled by at least two or more slide switches. By switching on the appropriate attenuators, the attenuation can be increased or decreased in decibel steps. Attenuators may be constructed in the 'T' or 'Π' configuration. The 'T' resistive network configuration includes two switchable series resistive elements and a switchable parallel resistive element connected between the series resistive elements. In this device the minimum attenuation level is achieved when the switchable series resistors are at a minimum resistance value and the switchable parallel resistor is at a maximum resistance value. The attenuation is obtained by decreasing the switchable parallel resistor and increasing the switchable series resistors. The 'Π' resistive network configuration includes two switchable parallel resistive elements and a switchable series resistive element, connected between two parallel resistive elements. In this device, the minimum attenuation level is achieved when the switchable series resistor is at a minimum resistance value and the switchable parallel resistors are at a maximum resistance value. The attenuation is obtained by decreasing the switchable parallel resistors and increasing the switchable series resistor. For a variable 'Π' resistive network configuration, the switchable parallel resistors must be 'ganged' (connected to a common actuator shaft of the switch) so that their resistances change together. This can be achieved by mechanically linking or ganging two movable wipers moving in unison across two sets of terminals as mentioned above.

Correction or pre-correction equalizers are available in a variety of values, capable of compensating losses accumulated across the coaxial cable length, ranging from zero to 15dB or more. The equalizer provides a predetermined loss at the lower end of the broadband television signal spectrum and a small loss at the high end of the frequency spectrum respectively. The variable-slope equalizer is comprised of a series resonant circuit, a parallel resonant circuit, a switchable attenuator circuit and a balun transformer. For allowing the variable-slope equalizer to operate as intended at frequencies up to 1000MHz or more, the parasitic elements, such as the inductance of traces on the printed circuit board and stray capacitances between or within the elements, must be considered in the design. The switchable attenuator circuit may be configured to have low stray capacitance and parasitic inductance for the switchable attenuator circuit to function as a predominantly resistive attenuator circuit even at frequencies up to 1000MHz or more.

The radio-frequency circuits, implemented as mechanically commutated attenuator or equalizer circuits, can be applied to many electronic products, which are intended for CATV/MATV/SMATV cable television network systems and individual receiving systems. Most of these circuits, designed for the radio-frequency level attenuation or frequency dependence correction, function in the schemotechnical-elemental base of the double-pole slide switches or commutated switches with only few commutation positions, i.e. DP2T or DP3T.

In case of the double-pole two-throw slide switches or commutated switches, i.e. when the radio-frequency circuit is implemented in the base of the mechanical switch of DP2T type, both double-pole commutation positions can be used for changing the required radio-frequency signal level or one of them can be the radio-frequency signal by-pass path with '0dB' attenuation value, or both double-pole commutation positions can be used for the frequency dependence correction of the radio-frequency signal, etc. For example, a radio-frequency circuit is presented in the Japanese patent No.JP7131776, which includes a double-pole two-throw slide switch, i.e. DP2T type, having the equalizer circuits of different functional purposes connected to both commutation positions of the slide switch.

In case of the double-pole three-throw slide switches or commutated switches, i.e. when the radio-frequency circuit is implemented in the mechanical switch (of DP3T type) base, the central double-pole commutation position is normally used for the radio-frequency signal transmission, i.e. like the radio-frequency signal by-pass path without attenuation function or with a very low attenuation level, while the side double-pole commutation positions are used for changing the required signal level, i.e. like the signal level correction paths. For example, an adjustable attenuator circuit, presented in the Japanese patent No.JP2003324327 as an integral part of the patented scheme is the radio-frequency circuit with the double-pole three-throw switch (of DP3T type), having '3dB' attenuator circuit connected to its upper commutation position, '5dB' attenuator circuit connected to the lower commutation position while the central commutation position is the signal by-pass path, i.e. transmitting the signal with no attenuation or with a very low attenuation level value. These are the conventional examples of such radio-frequency circuits.

The review of the literature related to the inventions in this field, and the analysis of the technical solutions for the electronic products proposed in the global cable television market revealed a number of patents worth to be mentioned in order to evaluate the general technical level of this field. For example, there is an already known Chinese patent No.CN2901737 which presents a scheme, conventional by now, of the adjustable radio-frequency equalizer, consisting of the adjustable attenuator, transformer and passive reactive elements. The schemotechnical circuit, described in this patent, is not complicated, featuring the low cost of the implementation. The equalizer is reliably adjusted and easily controlled. The control method described in the above patent can be applied for the invention discussed further.

There is another known US patent No.US7683732, presenting an improved conventional scheme of the adjustable equalizer which consists of the sequential LC path, present between the radio-frequency signal input and output terminals, the attenuator circuit with stepped control, the parallel LC path present between the general terminal of the controlled attenuator and the topological ground and the radio-frequency transformer. It is declared that the provided scheme functions in the frequency range from 50MHz to 1000MHz. The provided scheme features small insertion losses - not exceeding 1dB - and rather good return losses - above 18dB in the whole frequency band. One of the focused advantages of the provided scheme is the sustainability of uninterruptible transmission of information during the maintenance period, when replacing one element of the equalizer circuit with another, which is especially important nowadays. This is ensured by the sequential LC path present between the radio-frequency signal input and output terminals. At the same time, it is an integral part of the equalizer forming the transmission characteristic of that scheme. The method of control described in this patent can also be applied for our invention which will be discussed later.

The other known Japanese patent No.JP2005192026 demonstrates the radio-frequency scheme, allowing commutation of the attenuator, the simple television signal transmission line and power supply to the next radio-frequency scheme by using the slide switch of DP3T type. The double-pole three-throw commutated switch, i.e. DP3T type, is used in the provided radio-frequency circuit and power supply commutation circuit, the side position of which is connected with the radio-frequency signal-by-pass path, i.e. transmitting the signal without attenuation or having very low attenuation level value; the central commutated position is connected with the attenuator circuit, while the third side commutated position is the radio-frequency signal by-pass path, having no attenuation or a very low attenuation level value, when it is used for the power supply to the next radio-frequency scheme. This is another conventional example of the implementation of the radio-frequency circuits, having additional functions, by using the mentioned slide switches of DP3T type, in this case also by commutating the power supply to the next radio-frequency scheme.

It is also necessary to mention the Japanese patent No.JP7131385, which presents various schemotechnical solutions for commutating not only attenuator circuits, but also equalizer circuits, including their different combinations. All provided schemotechnical solutions use slide switches of DP2T or DP3T type. This patent is important for the evaluation of the general technical level, and it shows that the commutation type of the attenuators, equalizers and transmission lines with '0dB' attenuation value when commutating them by the same slide switch of DP2T or DP3T type, is known in the cable television networks for many years as a schemotechnical solution.

Moreover, an international application No.WO9504406 is known, which presents the assembly of the radio-frequency equalizer circuit, where the commutated part consists of the reactive elements and the resistive elements are controlled by the adjustable attenuator. Controlling this kind of equalizer is quite complicated; nevertheless the proposed solution is interesting in the schemotechnical aspect.

In order to avoid interruption of the television signal when it is switched over, the Japanese patent No.JP5327387 offers not to commutate the sequential path of the attenuator, i.e. keep the sequential resistive element of the attenuator circuit connected all the time. The issue of the signal continuity has been relevant for many years, therefore many different solutions were proposed (for example, this issue was analyzed and tried to be solved in the Japanese patents No.JP7079126, No.JP2007027929 and No.JP2007295481).

There is one more known European patent No.EP0208441 presenting the radio-frequency circuit, the structure and principle of which are based on the controlled LC path, inserted parallel to the commutated attenuator circuit, just between the contact terminals, able to adjust the required electrical length of that LC path by changing the value of the capacitive element, when that capacitive element is implemented as a trimmer capacitor. It is emphasized that the provided schemotechnical solution allow forming the attenuator circuit from the considerably bigger elements, as well as moving it away from the switch commutating the attenuator circuit, i.e. significantly reduces the constructive-topological requirements for that circuit according to the occupied area. The patent description emphasizes that the scheme occupying a larger area has better cooling properties, its elements are less sensitive to the distribution of the overall sizes of those elements, transmission characteristic is less distributed, the scheme is practical for controlling and performing the required transmission characteristic compensation when using the trimmer capacitor, and that this scheme is completely not sensitive to mechanical-electrical distribution in the way that even after changing the commutated switch, implemented in the base of the electrical relay, with the other switch of the same kind, does not require an additional adjustment or compensation of the radio-frequency circuit.

The insertion of the constructive element or the whole constructive-topological element is described in the US patent No.US4330765. This patent analyzes the radio-frequency circuit, consisting of the double-pole two-throw, i.e. DP2T type, electrically commutated switch and two radio-frequency commutated circuits - topological attenuator circuit and radio-frequency signal by-pass path - topological microstrip line path, placed in a shortest way between the switch contact terminals, i.e. on a place where they are presented one against another and belonging to one pair or throw. The purpose of the radio-frequency circuit is connecting one of the two radio-frequency commutated circuits - or the topological attenuator circuit, or the radio-frequency signal by-pass path with the minimal radio-frequency signal insertion losses. The patent description emphasizes that ideally the radio-frequency circuit of this type, when the commutated switch connects the topological attenuator circuit, will have an equal radio-frequency signal attenuation characteristic that does not depend on the frequency of the transmitted signal. However, due to the consistent parasitic capacity of the switch, the transmission characteristic of the radio-frequency circuit becomes frequency dependent - instead of being regular and independent of the frequency of the transmitted signal it constantly increases, i.e. the radio-frequency signal attenuation level steadily decreases. To avoid this, the inventor, relying on the significant consistent parasite capacity, observed that in the whole frequency range from DC to 2000MHz and higher it is possible to reach the regular radio-frequency signal transmission characteristic independent of the frequency of the transmitted signal by controlling the overall electrical length of the commutated structure, namely the topological structure of the radio-frequency attenuator circuit and the connected paths. This equals to the insertion of the sequential reactive element, in this case the inductive element or the equivalent topological microstrip line path segment, between the contact terminals, presented one against another and belonging to one pair or throw, of the electrically commutated switch, where the commutated attenuator circuit is placed.

The conventional radio-frequency circuit in which the slide switch is used is described in the Japanese patent No.JP2002261562. The radio-frequency circuit consists of the double-pole two-throw, i.e. DP2T type, slide switch and two radio-frequency commutated circuits - topological attenuator circuit and radio-frequency signal by-pass path - topological microstrip line path, installed between the switch contact terminals, presented one against another and belonging to one pair or throw. The purpose of the radio-frequency circuit is connecting one of the two radio-frequency commutated circuits - either the topological attenuator circuit or the radio-frequency signal by-pass path with the minimal radio-frequency signal insertion losses. In this case, the resistive element, present in the sequential path of the commutated attenuator circuit, is inserted close to the housing of the slide switch and connected to its contact terminals through the long topological microstrip line paths of inductive nature. To compensate the parasitic capacity of the attenuator circuit existing in the parallel paths directed to the topological ground, which occurs between the constructive site terminals of the slide switch and the topological ground, normally causing unwanted signal insertion losses, the author of said invention inserts an inductive element or equivalent topological microstrip line path segments. This is the conventional and well-known radio-frequency signal compensation method, mentioned in the above referred European patent No.EP0208441 and the US patent No.US4330765. As it is indicated in the above referred Japanese patent No.JP2002261562, if needed for the transmission characteristic equalization, in the sequential part of the commutated attenuator circuit, when the commutated circuit does not have too big parasitic capacity of that switch, the corrective element of capacitive nature is inserted parallel to the resistive element of the attenuator circuit, close to the slide switch; however, this constructive-topological schemotechnical solution of elements arrangement is not optimal (though it gives a considerable positive effect as seen from the electrical radio-frequency characteristics provided in the description of the above invention), because the capacitive element is inserted close to the housing of the slide switch and connected through the long topological microstrip line paths of inductive nature.

After analyzing the US patent No.US4330765 and the Japanese patent No.JP2002261562, the summing up conclusions will be used in our constructive-topological schemotechnical solution.

In the first case, when the frequency dependence of the transmission characteristic of the radio-frequency circuit is constantly increasing, i.e. the radio-frequency signal attenuation level steadily decreases, the inductive elements are inserted in the sequential path of the commutated attenuator circuit and the capacitive elements are inserted in the parallel paths of the commutated attenuator circuits. In this case the capacity between the terminals of the radio-frequency circuit, generated between the slide switch contact terminals, which are presented one against another and belonging to one pair or throw, is dominating.

In the second case, when the frequency dependence of the transmission characteristic of the radio-frequency circuit is constantly decreasing, i.e. the radio-frequency signal attenuation level steadily increases, the capacitive elements are inserted in the sequential path of the commutated attenuator circuit and the inductive elements are inserted in the parallel paths of the commutated attenuator circuit. In this case the consistent capacity between the terminals of the radio-frequency circuit, generated between the slide switch contact terminals, which are presented one against another and belonging to one pair or throw, is small comparing with its parasitic capacity, which is generated in the commutated attenuator circuit parallel paths directed to the topological ground, between the constructive terminals of the slide switch and the topological ground.

Consequently, it was noted that the use of the slide switch of small overall size, which has a very small consistent capacity between the terminals, may lead to employing the second above mentioned case, which is very beneficial for our constructive-topological schemotechnical solution, when the capacitive elements are inserted in the sequential paths of the commutated attenuator circuits, parallel to the resistive elements of the attenuator circuits, and the inductive elements are inserted in the parallel paths of the commutated attenuator circuits, in series to the resistive elements of the attenuator circuits for balancing and stabilizing the transmission characteristic of the radio-frequency circuit.

After analyzing the constructive-topological schemotechnical solutions for radio-frequency circuits implementation on the printed circuit boards of the electronic products, used in CATV/MATV/SMATV cable television network systems and individual receiving systems, it is evident that one of the closest analogues for our proposed radio-frequency constructive-topological schemotechnical solution, which will be discussed further, is the technical solution used by the German company 'KATHREIN-Werke'. For its electronic products the company uses the radio-frequency circuit, implemented in the base of the double-pole three-throw (DP3T) slide switch, with three adjustable attenuation level values, for example, '3dB'-'0dB'-'6dB' or other, the values of which are not coherently arranged, i.e. neither in increasing nor in decreasing sequence, and, as mentioned above, there are only three commutation positions. Obviously, the evaluation of the overall technical level also revealed other topologically available solutions, when the attenuation values are arranged in a sequentially increasing order, however, regarding the high-frequency characteristics, the optimal technical solution is the one that uses the mentioned double-pole three-throw, i.e. DP3T type, slide switches. This example shows that the central position of the slide switch is the radio-frequency signal transmission position, having no attenuation or a very low attenuation level value, and both side positions of the slide are connected with the commutated attenuator sets for indicating the required attenuation level value; one '3dB' attenuator set on one side of the slide switch, the other '6dB' attenuator set - on the other side of the same slide switch.

The reason is solely constructive and topological why only maximum the double-pole three-throw commutated switches are used in the passive and active broadband equipment, which are intended for CATV/MATV/SMATV cable television network systems and individual receiving systems. The slide switch fitted on the printed circuit board usually allows only three positions for commutating: the central position is retained for the radio-frequency signal transmission line with '0dB' attenuation, i.e. having no attenuation or a very low attenuation level value, while each side position of the slide switch provides for the insertion of one commutated radio-frequency circuits (as it was mentioned before, electronic products of 'KATHREIN-Werke', which are intended for the cable television network systems, are implemented in this way) due to the constructive-topological 'by-pass' issue related to this kind of slide switch. It is related to the need for the radio-frequency circuit to function in a more wide frequency range, which is intended for CATV/MATV/SMATV cable television network systems and individual network systems, therefore the commutated attenuator circuits, as well as their sequential and parallel paths, have to be characterized as having extremely low parasitic values of the elements of those paths. This can be achieved when the resistive values of elements of the commutated attenuator circuits considerably dominate against the reactive values of the elements of those paths. Since the attenuator sets are commutated by the slide switch, the parasitic capacities between the terminals of this switch generated between the housing and the topological ground automatically integrate into the parallel paths of the commutated attenuator circuit and notably impair the electrical radio-frequency characteristics of the whole radio-frequency circuit. In addition, when inserting the required additional commutated attenuator sets on both sides of the slide switch in attempt of the constructive-topological 'by-pass' in respect of the slide switch housing, the long inductive topological microstrip line paths with the parasite capacity are unavoidable and that considerably impairs electrical radio-frequency characteristics of that circuit, resulting in a notably narrower frequency range.

Fig.1 shows an overall dimensional view of the constructive-topological schemotechnical solution of the conventional radio-frequency circuit implemented in the base of the double-pole three-throw (DP3T) slide switch, well-known and commonly used in the electronic products which are designed for CATV/MATV/SMATV cable television network systems and individual receiving systems, when the central commutation position of the slide switch is intended for the radio-frequency signal transmission line with '0dB' attenuation, i.e. having no attenuation or a very low attenuation level value, and on both sides of the slide switch the commutated attenuator sets are placed, in this way not following the variation sequence of the radio-frequency signal attenuation level values, when the wiper handle moves in one selected direction through all three commutation positions of the slide switch, as it was mentioned in the description of 'KATHREIN-Werke' constructive-topological solution. The first figure (Fig.1) also presents how these radio-frequency circuits are cascaded, i.e. series connected one after another. The mentioned drawing illustrates the cascading of two circuits. As it is shown, the whole radio-frequency circuit is implemented in the base of two double-pole three-throw slide switch. This is the conventional art sample of using such circuits in the cable television networks. Fig. 2 illustrates the conventional art sample of the principal scheme of constructive-topological solution presented in Fig.1. Normally, there are two, three and more cascades in the cable television networks to expand the range of the radio-frequency signal attenuation levels or to expand the range of the controlled step values.

Technical Problem

Technical Solution

Radio-frequency circuits, implemented in the housing of the double-pole, more than three-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc., DPMT), slide switch, are not very common in the passive and active broadband equipment, which is belonging to CATV/MATV/SMATV cable television network systems and individual receiving systems intended for the cable networks for television signals, sound signals and interactive services, but the implementation of our proposed radio-frequency constructive-topological schemotechnical solution distinguished for radio-frequency signal level adjustment circuits implemented on the base of the double-pole multi-throw slide switches of 4, 5 or even 6 and higher commutation positions (DP4T, DP5T, etc., DPMT), in the passive and active broadband equipment of these systems and networks, would be very practical and universal.

The aim of this radio-frequency constructive-topological schemotechnical solution is the radio-frequency circuit of a special assembly, for example, adjustable attenuator, equalizer or other circuit created for a similar purpose, where slide switches of 'make-before-brake' type, having more than three double-pole commutation positions, are used. These slide switches effectively ensure uninterrupted television signal transmission in all frequency range assigned for CATV/MATV/SMATV cable television network systems and individual receiving systems.

The essence of this invention is that into the above mentioned adjustable attenuator, equalizer or other radio-frequency circuit, created for the similar purpose, which is implemented on the base of the commutated attenuator sets, between all contact terminals, i.e. on a place where they are presented one against another and belonging to one pair or throw, of the double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc., DPMT), slide switch, where the commutated attenuator set is placed, at least one resistive constructive component of '0402' or of other similar overall size is inserted, and if required, for frequency characteristic correction, the other passive component of reactive nature is inserted. In this way the technological effect is reached, the essence of which is that when commutating attenuator sets with double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc. DPMT), slide switch, which constructively-topologically combines the commutated attenuator sets, it is possible to control the radio-frequency transmission characteristic of not only attenuator, but also the equalizer or other functional radio-frequency circuit, implemented in this way, when the control principle of the attenuator, equalizer or other radio-frequency circuit, created for a similar purpose, is the commutation of the mentioned attenuator sets, covering now a more wide part of the frequency range which is assigned for CATV/MATV/SMATV cable television network systems and individual receiving systems, at the same time improving the electrical radio-frequency characteristics in the lower frequency part of this range. This new radio-frequency constructive-topological schemotechnical solution ensures the usage of the 4, 5, 6 or higher commutation positions in the passive and active broadband equipment, which is belonging to CATV/MATV/SMATV cable television network systems and individual receiving systems, intended for cable networks for television signals, sound signals and interactive services. Moreover, it does not negatively affect electrical radio-frequency characteristics for the radio-frequency circuits of lower order, i.e. having 3 or 2 commutation positions, currently commonly used in the electronic products of these network systems, if they are implemented by applying our proposed technical solution. Furthermore, when commutating the attenuator sets with double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc., DPMT), slide switch, constructively-topologically combining the attenuator sets, i.e. when the wiper handle of the slide switch moves from one commutation position to another, it is possible to change the attenuation level value of the signal, transmitted through the radio-frequency circuit, in a selected sequentially increasing (decreasing) order, for example, '0dB', '4dB', '8dB', '12dB', etc., or in other step, which ensures a consequtive accurate sequence of the change of the radio-frequency signal attenuation level values, or the accurate discrete sequence of the change of the angles of the increasing/decreasing transmission characteristic, when a scheme of the adjustable equalizer is used, functioning on the base of the commutated attenuator sets.

This visibly facilitates the maintenance of the electronic products used in CATV/MATV/SMATV cable television network systems and individual receiving systems because of the time saved for the maintenance personnel of the mentioned networks, needed for identifying the radio-frequency signal level and, while using of several series connected radio-frequency circuits with the different attenuation level value settings facilitates the identifying of the attenuation level values even more.

The essential features of this invention are the following:

the main new feature is the usage of the double-pole multi-throw slide switch with the resistive components at the same time, when they are inserted straight under the housing of the double-pole multi-throw slide switch, between the switch contact terminals, i.e. straightly on a place where they are presented one against another and belonging to one pair or throw, or on the opposite side of the printed circuit board between the same contact terminals, which are normally inserted through holes in the board;

a component of the sequential path of the commutated attenuator set is inserted between the switch contact terminals, which are presented one against another and belonging to one pair or throw; normally it is a constructive of '0402' size (1x0,5x0,5mm overall size) resistive component and, if required, for the frequency characteristic correction, component of capacitive nature is used, the overall size of which is constructively combined with the arrangement of the sites of the double-pole multi-throw slide switch contact terminals, presented one against another and belonging to one pair or throw; the components of the constructive '0402' size allow reaching the maximum possible integration according to the arrangement of the components and, at the same time, expanding the limits of usage of this radio-frequency constructive-topological schemotechnical solution, coverig now a more wide part of the frequency range which is assigned for CATV/MATV/SMATV cable television network systems and individual receiving systems, at the same time improving electrical radio-frequency characteristics in the lower frequency part of this range; insertion of the constructive component of '0402' size between the double-pole multi-throw slide switch contact terminals, presented one against another and belonging to one pair or throw, allows implementing new radio-frequency constructive-topological schemotechnical solutions, which would be impossible if constructive-topological solutions of the conventional art would be applied;

to compensate the parasitic capacity of the attenuator circuit, existing in the parallel paths directed to the topological ground, which occurs between the contact terminals of the double-pole multi-throw slide switch and the topological ground, which normally causes unwanted radio-frequency signal insertion losses, the inductive elements or equivalent topological microstrip line path segments are inserted into the parallel parts, directed to the topological ground, of the commutated attenuator sets, sequentially to the resistive components of the parallel paths of the same sets; in case of this radio-frequency constructive-topological schemotechnical solution, low topological inductance is sufficient for reaching the compensation or equalization of the radio-frequency signal level in a more wide frequency range, which is intended for CATV/MATV/SMATV cable television network systems and individual receiving systems;

insertion of the above mentioned resistive component of '0402' overall size or its equivalent under the housing of the double-pole multi-throw slide switch allows implementing not only the commutated attenuator circuits of high integration level, but also the commutated equalizer circuits by commutating only their resistive components, leaving the reactive elements not commutated, when the equalizers are implemented in the base of the commutated attenuator circuits;

the above mentioned resistive component, double-pole multi-throw having more than three throws, i.e. 4, 5, etc. commutation positions (DP4T, DP5T etc., DPMT), slide switch, attenuator circuit and the equalizer circuit implemented in its base, as well as the application of all these components in one radio-frequency constructive-topological schemotechnical solution of the higher component arrangement integration, considerably facilitates

assimilation of nearly all frequency range, which is assigned for CATV/MATV/SMATV cable television network systems and individual receiving systems, regulated by the International Standard IEC 60728, i.e. covering now a more wide part of the frequency range, which is intended for these network systems, at the same time improving electrical radio-frequency characteristics in the lower-frequency part of this range,

and at the same time keeps unchanged

the principle of uninterruptible operation of that network when the mechanical sliding movement of the handle from one position to another is performed by using the wiper handle of the slide switch.

Our proposed radio-frequency constructive-topological schemotechnical solution allows to reach a considerable improvement of the reflection coefficient and other related radio-frequency electrical parameters in the frequency range, which is assigned for CATV/MATV/SMATV cable television network systems and individual receiving systems, covering now a more wide part of this range and at the same time improving electrical radio-frequency characteristics in the lower frequency part of this range.

The above indicated essential features of our technical solution not only allow to launch new adjustable radio-frequency attenuators, implemented in their base equalizers and related electronic products into the global cable television market, but also implementing of new schemotechnical solutions, which would be not available in assembly form if conventional topological schemotechnical solutions would be used.

Advantageous Effects

Description of Drawings

Fig. 1 shows the conventional overall dimensional view of the radio-frequency circuit implemented in the base of the double-pole three-throw (DP3T) slide switch, which is well-known and commonly used in CATV/MATV/SMATV cable television network systems and individual receiving systems, when the central position of the slide switch is intended for signal transmission line with '0dB' attenuation, i.e. has no attenuation or a very low attenuation level value, and on the sides of the slide switch commutated attenuator sets are placed; in this way the wiper handle moves in one selected direction through all three positions of the slide switch not following a sequential variation order of the radio-frequency signal attenuation level. The first figure (Fig.1) also presents how these radio-frequency circuits are cascaded, i.e. sequentially connected one after another. The above mentioned drawing shows the cascading of two circuits. As it is shown, all radio-frequency circuit is implemented in the base of the double-pole three-throw slide switches. This is the conventional art sample of the usage of these circuits in the cable television networks. Normally, two, three or more cascades are used in the cable television networks in order to expand the range of the radio-frequency signal attenuation levels or to expand the range of the controlled step values.

Fig.2 shows the principal scheme of the conventional constructive-topological schemotechnical solution presented in the first figure (Fig.1).

Fig.3 presents an overall dimensional view of the constructive-topological schemotechnical solution of the radio-frequency circuit, based on our invention, implemented in the base of the double-pole, more than three-throw, i.e. six commutation positions (DP6T) slide switch, when the side position of slide switch is intended for the radio-frequency signal transmission line with '0dB' attenuation, i.e. having no attenuation or a very low attenuation level value, while to the rest free commutation positions the commutated attenuator sets are placed with constantly increasing radio-frequency signal attenuation level values in respect of the side '0dB' commutation position.

Fig.4 provides part 'View_A' of an overall dimensional view, presented in the third figure (Fig.3), where the above mentioned resistive components, inserted between the double-pole multi-throw slide switch contact terminals, i.e. on a place where they are presented one against another and belonging to one pair or throw, are presented on a larger scale, when they are implemented as the components of the sequential paths of the commutated attenuator sets.

Fig.5 shows the principal scheme of our proposed constructive-topological schemotechnical solution, presented in the third figure (Fig.3).

Fig.6 presents an overall dimensional view of our proposed constructive-topological schemotechnical solution of the radio-frequency circuit, implemented in the base of the double-pole four-throw (2xDP4T) slide switches, when that circuit is implemented as two sequentially connected commutated attenuator circuits, characterized in that the first (for example, the left) has a step controlled by the radio-frequency signal attenuation level value set to 1 decibel, while the second - to 4 decibels.

Fig.7 shows the principal scheme of our proposed constructive-topological schemotechnical solution, presented in the sixth figure (Fig.6), as an example of its implementation.

Fig.8 presents an overall dimensional view of our proposed constructive-topological schemotechnical solution of the radio-frequency circuit, implemented in the base of the double-pole four-throw (2xDP4T) slide switches, when that circuit is implemented as two sequentially connected commutated attenuator and equalizer circuits, allowing to gain any transmission characteristic, both balanced horizontally and in a preferred increasing angle.

Fig.9 shows the principal scheme of our proposed constructive-topological schemotechnical solution, presented in the eighth figure (Fig.8) as an example of its implementation.

Best Mode

Now in the global electronics industry, new series of electronic components of very small geometrical dimensions, i.e. 1x0.5x0.5mm, so called '0402' or even smaller overall size, having resistive, capacitive or inductive nature, are released on a mass scale. It was noticed that when constructively-topologically arranging the surface mount components of sequential paths (502r-504r, etc.) of commutated attenuator sets (502s-504s, etc.), straight under the housing of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), by using the above mentioned components of very small overall size having resistive or, for transmission characteristic correction, reactive nature, between the slide switch (SA1) contact terminals (SA1c), i.e. on a place where they are presented one against another and belonging to one pair or throw (SA1T), or on the opposite side of the printed circuit board (301) between the same contact terminals (SA1c), which are normally inserted through holes in the board (301), where the commutated attenuator set (502s-504s, etc.) is placed, it is possible to significantly expand the usage of the frequency range, which is intended for CATV/MATV/SMATV cable television network systems and for individual receiving systems, as well as to achieve an entirely new positive effect, resulting from our proposed constructive-topological schemotechnical solution (300-500), which is comprehensively described further.

In order to have more than three commutation positions (501p-504p, etc.) of the radio-frequency signal attenuation level values (SA1v) of the commutated attenuator or equalizer (300-500), it is necessary to search for new constructive-topological schemotechnical solutions. One of such technical solutions, helping to achieve our aims, is the proposed constructive-topological schemotechnical solution (300-500), an overall dimensional view (300) of which is presented in the third figure (Fig.3), including all inserted resistive components (R2,R5,R8, etc.), part of which (R2,R5) is presented in more detail in the fourth figure (Fig.4) as 'View_A'. The principal scheme (500) of this constructive-topological schemotechnical solution (300-500) is presented in the fifth figure (Fig.5).

In general, our proposed constructive-topological schemotechnical solution (300-500) is related to the double-pole (SADP) multi-throw, i.e. of 4, 5, etc. commutation positions (DP4T, DP5T, etc., DPMT) (501p-504p, etc.), slide switches (SA1) of small overall sizes and of 'make-before-brake' type, which would be suitable for designing cable television electronic circuits (300-500) and their embodiment on the printed circuit boards (301), however, as an illustration of our proposed technical solution (300-500), a specific, one of plenty available, double-pole (SADP) multi-throw, i.e. of six positions (DP6T) (501p-506p), slide switch (SA1) of small overall size with 'make-before-brake' characteristic is chosen.

The third figure (Fig.3) presents a general dimensional view (300) of our proposed constructive-topological schemotechnical solution (300-500) of the radio-frequency circuit assembly (300-500), implemented in the double-pole (SADP), more than three-throw, i.e. six commutation positions (DP6T) (501p-506p), slide switch (SA1), when the side position (501p) of the slide switch (SA1) is intended for the radio-frequency signal transmission line (507) with '0dB' attenuation level value (SA1v), i.e. having no attenuation or having a very small attenuation level value, and to the rest free commutation positions (502p-506p) the commutated attenuator sets (502s-506s) are placed with constantly increasing radio-frequency signal attenuation level values (SA1v) in respect of the side '0dB' commutation position (501p). All radio-frequency signal attenuation level values (SA1v) of the commutated attenuator sets (502s-506s) are set in a way that the provided circuit (300-500) would allow managing the radio-frequency signal attenuation level values (SA1v) in a sequentially increasing (decreasing) order through all the way (SA1a) of the wiper handle (SA1h) movement in its (SA1h) chosen moving direction (SA1d), in this way ensuring a consecutive accurate sequence of the change of the radio-frequency signal attenuation level values (SA1v) through all the way (SA1a) of the handle (SA1h) movement.

(NOTE: for better understanding, the third figure (Fig.3) shows the slide switch (SA1) separately from the printed circuit board (301), therefore in the printed circuit board (301) only the metalized contact holes (18xSA1c) are seen, which are used for installing the contact terminals (18xSA1c) of the switch; hereafter both of the sides of the contacts (18xSA1c) are marked in the same way for the sake of simplicity.)

The fourth figure (Fig.4) presents an expanded part of the general dimensional view of our constructive-topological schemotechnical solution (300-500), shown in the third figure (Fig.3) as 'View_A', where a few of the above mentioned resistive components (R2,R5) are presented in a larger scale, placed between the contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-506p) slide switch (SA1), when they (R2,R5) are implemented as resistive components (R2,R5) of the sequential paths (502r,503r) of the commutated attenuator sets (502s,503s). Between all contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-506p) (in this example, six commutation positions) (DP6T) slide switch (SA1), where the commutated attenuator set (502s-506s) is placed, at least one constructive '0402' or of other similar overall size, resistive component (R2,R5,R8) is inserted, moreover, if required, the other passive component of reactive nature is to be inserted as well. Components of reactive nature, for example, components of capacitive nature, that are to be inserted between the slide switch (SA1) contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), are not shown in this figure.

The fifth figure (Fig.5) shows the principal scheme (500) of our constructive-topological schemotechnical solution (300-500), presented in the third figure (Fig.3), that allows managing the radio-frequency signal attenuation level values (SA1v) in a sequentially increasing (decreasing) order through all the way (SA1a) of the wiper handle (SA1h) movement in its (SA1h) chosen moving direction (SA1d), in this way ensuring a consecutive accurate sequence of the change of the radio-frequency signal attenuation level values (SA1v) though all the way (SA1a) of the handle (SA1h) movement. The fifth figure (Fig.5) also shows an internal structure of the wiper (SA1w) of the slide switch (SA1), presented in the schemotechnical manner, which (SA1w) performs the commutation procedure of the attenuator sets (502s-506s), when the wiper handle (SA1h) moves forward / backward (SA1d) through all the commutation positions (502p-506p) of the slide switch (SA1) in one or another its (SA1h) moving direction (SA1d), including the commutation position (501p) with '0dB' attenuation level value (SA1v).

The radio-frequency circuit assembly (300-500), implemented in accordance with the structure of the double-pole (SADP) multi-throw (501p-506p), in this particular case, six commutation positions, slide switch (SA1) and commutated attenuator sets (502s-506s), consists of the elements or parts of their groups, which are listed below. The mentioned circuit (300-500), analyzed here as one of the simplest versions of the proposed radio-frequency constructive-topological schemotechnical solution (300-500), includes:

one radio-frequency signal input terminal ' RFin ' (508) for transmitting the radio-frequency signal to the radio-frequency circuit (300-500) , functioning in accordance with the commutation principle;

one radio-frequency signal output terminal 'RFout' (509) for removing the radio-frequency signal from the radio-frequency circuit (300-500), functioning in accordance with the commutation principle;

one double-pole (SADP) multi-throw (501p-506p), in this particular case six commutation positions, (DP6T) slide switch (SA1) with an integrated wiper handle (SA1h), implemented in the constructive form; which has

six commutation positions (501p-506p);

eighteen contact terminals (18xSA1c);

six groups of contact terminals (SA1c), presented one against another:

(S1,S18), (S2,S17),(S3,S16),(S7,S12),(S8,S11) and (S9,S10) to which the commutated attenuator sets are connected and which are further referred to as the throws;

two groups of adjacent contact terminals (SA1c), presented one by another: (S1-S9) and (S10-S18), which are further individually referred to as the polar contact groups or simply poles (SADP);

one doubled wiper (SA1w) of the slide switch (SA1), mechanically linked to the wiper handle (SA1h), allowing to commutate two contacts going not one after another in the first and the second polar contact groups (SADP) simultaneously, while it moves through all the commutation positions (501p-506p); as well as

five commutated attenuator sets (502s-506s), constructed in the configuration 'Π', consisting of the resistive components (R2,R5,R8,R11,R14) of the sequential paths (502r-506r) and the resistive components (R1,R3, R4,R6, R7,R9,R10,R12, R13,R15) of the parallel paths (502e-506e);

five resistive components (R2,R5,R8,R11,R14) of the sequential paths (502r-506r) of the commutated attenuator sets (502s-506s), each of which is separately inserted between the contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole multi-throw (501p-506p) slide switch (SA1);

reactive (in this case, capacitive nature) components of the sequential paths (502r-506r) of the commutated attenuator sets (502s-506s), if required for the frequency characteristic correction, each of which is separately inserted between the contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole multi-throw (501p-506p) slide switch (SA1), parallel to the resistive components (R2,R5,R8,R11,R14) of the sequential paths (502r-506r) of the same attenuator sets (502s-506s) (not shown in the drawing (500) and in the figure of the overall dimensional view (300);

five resistive component pairs (R1,R3,R4,R6, R7,R9, R10,R12, R13,R15) of the parallel paths (502e-506e) of the commutated attenuator sets (502s-506s), each of which is separately inserted between the contact terminals (SA1c) of the double-pole (SADP) multi-throw (501p-506p) slide switch (SA1) and the topological ground (302);

five component pairs of reactive nature (in this case, inductive nature) of the parallel paths (502e-506e) of the commutated attenuator sets (502s-506s) (not shown in the drawing (500)), each of which is inserted in the topological ground direction (302) from the contact terminals of the double-pole (SADP) multi-throw (501p-506p) slide switch (SA1), sequentially to the resistive components (R1,R3, R4,R6,R7,R9, R10,R12, R13,R15) of the parallel paths (502e-506e) of the same attenuator sets (502s-506s), and which can be constructively implemented in a form (303) of the topological microstrip line path (shown in the figure of the overall dimensional view (300) as one of the possible ways of their implementation);

fifteen resistive components (R1-R15), where every commutated attenuator set (502s-506s) includes three resistive components (R1-R3, R4-R6, R7-R9, R10-R12, R13-R15) of this nature;

at least nine resistive components (R1-R9, etc.), where every commutated attenuator set (502s-504s, etc.) includes three resistive components (R1-R3, R4-R6, R7-R9, etc.) of this nature;

one radio-frequency signal by-pass path (507), being between the side contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-506p) slide switch (SA1), from one side of the switch (SA1), and which (507) is characterized in that it (507) is considered to be the side commutation position (501p) of the slide switch (SA1), intended for the radio-frequency transmission line (507) with '0dB' attenuation level value (SA1v), i.e. having no attenuation or a very small attenuation lavel value, when it (507) is implemented in a form of the topological microstrip line path (507), and to the rest free commutation positions (502p-504p, etc.) the commutated attenuator sets (502s-506s) are placed with constantly increasing radio-frequency signal attenuation level values (SA1v) in respect of the side '0dB' commutation position (501p);

a segment of the printed circuit board (301), sufficient for inserting all the above mentioned circuit (300-500) components and parts of their groups.

As it is seen from the principal scheme (500), presented in the fifth figure (Fig.5) and its overall view (300), the radio-frequency attenuation level with '0dB' value (SA1v), i.e. when there is no attenuation or its level is very low, is reached when the wiper handle (SA1h) of the slide switch (SA1) is on the side commutation position (501p) of that switch (SA1), close to the radio-frequency signal by-pass path (507), while the radio-frequency signal is travelling this route: input terminal 'RFin' (508), wiper (SA1w) contacts (S4), (S1) of the switch (SA1), radio-frequency signal by-pass path (507), implemented in a form of topological microstrip line path (507), contacts (S18), (S15), output terminal 'RFout' (509); radio-frequency signal attenuation level with, for example, '4dB' value (SA1v), is reached when the wiper handle (SA1h) of the slide switch (SA1) is in the position (502p) next after the above mentioned side commutation position (501p), and while the radio-frequency signal is travelling this route: input terminal 'RFin' (508), contacts (S5), (S2), commutated attenuator set (502s) of 4 decibels, implemented in a form of resistors (R4,R5,R6), contacts (S17), (S14), output terminal 'RFout' (509); etc. In this way, when the wiper handle (SA1h) of the slide switch (SA1) is moving down through all those commutation positions (501p-506p), from one position to the other, it is possible to change the attenuation level value (SA1v) of the transmitted signal through the radio-frequency circuit (300-500) in the selected sequentially increasing order, for example, '0dB', '4dB', '8dB', '12dB', etc., or in other step, ensuring a consecutive accurate sequence of the change of the radio-frequency signal attenuation level values (SA1v).

This is achieved by applying our proposed constructive-topological schemotechnical solution, when between the double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc. DPMT) slide switch contact terminals, presented one against another and belonging to one pair or throw, is inserted a resistive component of the sequential path of the commutated attenuator set, i.e. into the above mentioned adjustable attenuator, equalizer or other radio-frequency circuit, which is implemented on the basis of the commutated attenuator sets, between all double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc. DPMT) slide switch contact terminals, which are presented one against another and belonging to one pair or throw, where the commutated attenuator set is placed, at least one constructive, of '0402' or other similar overall size, resistive component, and if required, the other passive component of reactive nature is inserted, the technological effect is reached, the essence of which is that by commutating all attenuator sets with double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc. DPMT), slide switch that combines the attenuator sets, it is possible to control the radio-frequency transmission characteristic not only of the attenuator, but also the equalizer or other functional radio-frequency circuit, implemented in this way, when the adjustment principle of the attenuator, equalizer or other radio-frequency circuit of a similar type is commutation of the above mentioned attenuator sets, covering now a more wide part of the frequency range intended for CATV/MATV/SMATV cable television network systems and individual receiving systems, at the same time improving electrical radio-frequency characteristics in the lower frequency part of this range. This new radio-frequency constructive-topological schemotechnical solution ensures the occurrence of the 4, 5, 6 or even higher commutation positions in the passive and active broadband equipment, belonging to CATV/MATV/SMATV cable television network systems and individual receiving systems, intended for the cable networks for television signals, sound signals and interactive services. Moreover, by commutating the attenuator sets with the double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc. DPMT), slide switch, that constructively-topologically combines the attenuator sets, i.e. when the wiper handle of the slide switch is moving from one position to the other, it is possible to change the attenuation value of the signal level transmitted through the radio-frequency circuit in a selected sequentially increasing (decreasing) order, for example, '0dB', '4dB', '8dB', '12dB', etc. or in other step, ensuring a consecutive accurate sequence of the change of the attenuation values of the radio-frequency signal, or the accurate discrete sequence of the change of the angles of the increasing/decreasing transmission characteristic, when the scheme of adjustable equalizer is used, functioning on the base of the commutated attenuator sets.

Normally, a constructive resistive component of '0402' size (1x0,5x0,5mm overall size) and, if required for the frequency characteristic correction, component of capacitive nature is applied. Other components of similar overall size can also be applied, the sizes of which are constructively adjusted with the arrangement of sites of the contact terminals, presented one against another and belonging to one pair or throw, of the double-pole multi-throw slide switch. The components of this constructive '0402' size allow reaching the maximum possible integration in respect of the arrangement of the components, as well as expanding the field of usage of this radio-frequency constructive-topological schemotechnical solution, covering now a more wide part of the frequency range which is intended for CATV/MATV/SMATV cable television network systems and individual receiving systems, at the same time improving electrical radio-frequency characteristics in the lower frequency part of this range. Insertion of the constructive component of '0402' size between the contact terminals, i.e. on a place where they are presented one against another and belonging to one pair or throw, of the double-pole multi-throw slide switch, allows implementing new radio-frequency constructive-topological schemotechnical solutions, which would not be possible if conventional constructive-topological schemotechnical solutions would be applied.

The parasitic capacity, existing in the parallel paths (directed towards the topological ground) of the commutated attenuator sets, occurring between the contact terminals of the double-pole multi-throw slide switch and the topological ground, which normally causes unwanted insertion losses of the radio-frequency signal, is compensated in the parallel paths (directed towards the topological ground) of the commutated attenuator sets, close to the resistive components of the parallel paths of the same commutated attenuator sets, by inserting an inductive element or a segment of the topological microstrip line path. In case of this radio-frequency constructive-topological schemotechnical solution, low topological inductance is sufficient for reaching compensation or equalization of the radio-frequency signal in a more wide frequency range, intended for CATV/MATV/SMATV cable television network systems and individual receiving systems. This constructive-topological schemotechnical feature, well-known and widely used by many companies, is very suitable for implementation of the proposed radio-frequency constructive-topological schemotechnical solution, because due to the parasitic capacity of the double-pole multi-throw slide switch it is necessary to move the above mentioned topological ground in a certain constructive distance from the housing of the slide switch.

Sometimes the parasitic capacity, occurring between the contact terminals, presented one against another and belonging to one pair or throw, of the double-pole multi-throw slide switch, where the commutated attenuator set is placed, due to the small overall size of the double-pole multi-throw slide switch, is too small. In this case, it is very practical in the sequential paths of the commutated attenuator sets, parallel to the resistive components of the sequential paths of the same sets, to insert a constructive component of '0402' size and of capacitive nature between the contact terminals, presented one against another and belonging to one pair or throw, of the double-pole multi-throw slide switch. It is a cost-efficient way of the radio-frequency signal level compensation, contributing to the implementation of the proposed radio-frequency constructive-topological schemotechnical solution.

Considering the fact that elementary cascading of the radio-frequency circuits is a common and conventional case in the cable television networks, and that the reflection coefficients of the above mentioned cascades, expressed in the linear decimal non-dimensional level, are summed up at their absolute value, make us to emphasize that in case of the proposed radio-frequency constructive-topological schemotechnical solution, when cascading the above mentioned radio-frequency circuits, we can reach a considerable improvement of the reflection coefficient and other related radio-frequency electrical parameters in a more wide part of the frequency range, including the lower frequency part of this range.

As an illustration of our proposed radio-frequency constructive-topological schemotechnical solution, a few cascading examples of the radio-frequency circuits are provided when in one case the circuit is implemented as two sequentially connected attenuator circuits, while in the second case this circuit is implemented as two sequentially connected attenuator and equalizer circuits.

It is seen that the sixth figure (Fig.6) shows an overall dimensional view of the proposed radio-frequency circuit, implemented in the housing of the two double-pole, four-throws (2xDP4T) slide switches, when the circuit is implemented as two sequentially connected commutated attenuator circuits, different among themselves because the step, controlled by the radio-frequency signal attenuation level value, of the first (for example, left) circuit is set to 1 decibel, while the second is set to 4 decibels. As a result, the maximum range of 25dB is reached, the step of which is set to 1 decibel through all the range. 2, 3 or more cascades of this type are normally present in the cable television networks to extend the range of the radio-frequency signal attenuation levels or to extend the range of the controlled steps values. In all cases, this only enhances the virtue of the proposed technical solution in respect of the reflection coefficient of this circuit. The seventh figure (Fig.7) presents the principal scheme of the proposed constructive-topological schemotechnical solution presented in the sixth figure (Fig.6).

It is seen that the eighth figure (Fig.8) shows an overall dimensional view of the proposed radio-frequency circuit, implemented in the housing of the two double-pole, four-throw (2xDP4T), slide switches, when the circuit is implemented as two sequentially connected circuits of the commutated attenuator and equalizer, allowing to get any of the transmission characteristics, balanced horizontally or in a preferred increasing angle. The ninth figure (Fig.9) shows the principal scheme of the proposed constructive-topological schemotechnical solution presented in the eighth figure (Fig.8).

As it is seen, the radio-frequency constructive-topological schemotechnical structure, implemented on the base of the proposed technical solution, is not confined to the implementation of the attenuator commutation circuit only. When applying this constructive-topological method of the components arrangement, it is easy to implement the commutated equalizer, when the commutated part is comprised only of resistive components and the other reactive components are not commutated. The positive effect is obvious, because in this way high-level component arrangement integration is reached. On the other hand, since the reactive components of this circuit are not commutated, minimally decreased amount of them reduces the electromagnetic interaction between them. Furthermore, an additional positive feature of this radio-frequency constructive-topological schemotechnical solution is a minimal possible distance between the controlled input and output contact terminals, emerging through the sequential L1C5 circuit (Fig.9) of the equalizer, which is not commutated also.

During the transitional period every new commutation position is connected before the old one is disconnected, i.e. without interrupting the radio-frequency signal. In this process, while the wiper handle is moving from one position to another, variation of the radio-frequency signal attenuation level is possible, however, it does not affect the quality of the radio-frequency signal, because the principle of uninterruptibility of the signal is retained. This depends on the internal mechanical 'make-before-brake' configuration structure of the wiper of the double-pole multi-throw slide switch. In certain cases of technical solutions the switches of 'make-after-brake' type can be used.

All devices mentioned in the examples are of surface mount devices, except for the slide switch, which can also be implemented as a surface mount component or even be comprised of two separate parts (in general, 2x1PMT).

For the sake of convenience, on the panel of the equipment, close to every double-pole multi-throw slide switch, the wiper handle of which is usually seen on the panel of the equipment, it is possible to put the correctly prepared scale with indicated attenuation level values, since our technical solution which we have proposed already, ensures an accurate arrangement of the radio-frequency signal attenuation level values.

The double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc., DPMT), slide switches of small size that are capable of commutating the radio-frequency signal, suitable for designing circuits for cable television electronic products and implementing them on the printed circuit boards, are not yet common in the global cable television market, however, the appearance of our radio-frequency constructive-topological schemotechnical solution without doubts will be noticed by the companies, producing electronic components, as well as motivate them to produce new and modern series of double-pole multi-throw, i.e. 4, 5, etc. commutation positions (DP4T, DP5T, etc., DPMT), slide switches for the global cable television market, capable of commutating the radio-frequency signal in a proper way, because the structure of the slide switches, currently used in the cable television market, is not fully suitable for implementation of the proposed invention, neither according to the overall sizes, nor the electrical radio-frequency characteristics.

While the particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention is to be limited only in terms of the appended claims.

Mode for Invention

Industrial Applicability

Sequence List Text

Claims

A radio frequency circuit assembly, comprising of:

at least one radio-frequency signal input terminal (508) for signal transmission to the radio-frequency circuit, functioning according to the principle of commutation;

at least one radio-frequency signal output terminal (509) for removing the radio-frequency signal from the radio-frequency circuit, functioning according to the principle of commutation;

at least one double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1) with an integrated wiper handle (SA1h), which is constructively implemented and has

at least four commutation positions (501p-504p, etc.);

at least twelve contact terminals (SA1c);

at least four groups of contact terminals (SA1c), presented one against another, to which the commutated attenuator sets are connected and which are further referred to as the throws (SA1T);

two groups of adjacent contact terminals (SA1c), which are further referred to as the polar contact groups or simply poles (SADP);

one doubled wiper (SA1w) of the slide switch (SA1), mechanically linked to the wiper handle (SA1h), allowing to commutate two contacts going not one after another in the first and the second polar contact (SADP) groups simultaneously, while it moves through all the commutation positions (501p-504p, etc.); as well as

at least three commutated attenuator sets (502s-504s, etc.), constructed in the configuration 'Π' or other, consisting of the resistive components (R2,R5,R8, etc.) of the sequential paths (502r-504r, etc.) and the resistive components of the same nature (R1,R3, R4,R6, R7,R9, etc.) of the parallel paths (502e-504e, etc.);

at least three resistive components (R2,R5,R8, etc.) of the sequential paths (502r-504r, etc.) of the commutated attenuator sets (502s-504s, etc.), each of which is separately inserted between the contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1);

at least one element of reactive nature of the sequential paths (502r-504r, etc.) of the commutated attenuator sets (502s-504s, etc.), if required for the frequency characteristic correction, each of which is separately inserted between the contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), parallel to the resistive components (R2,R5,R8, etc.) of the sequential paths (502r-504r, etc.) of the same attenuator sets (502s-504s, etc.);

at least three resistive component pairs (R1,R3,R4,R6, R7,R9, etc.) of the parallel paths (502e-504e, etc.) of the commutated attenuator sets (502s-504s, etc.), each of which is separately inserted between the contact terminals (SA1c) of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1) and the topological ground (302);

at least three element pairs of reactive nature of the parallel paths (502e-504e, etc.) of the commutated attenuator sets (502s-504s, etc.), each of which is inserted in the topological ground (302) direction from the contact terminals (SA1c) of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), sequentially to the resistive components (R1,R3, R4,R6,R7,R9, etc.) of the parallel paths (502e-504e, etc.) of the same attenuator sets (502s-504s, etc.), which can be constructively implemented in a form of the topological microstrip line paths (303);

at least nine resistive components (R1-R9, etc.), where every commutated attenuator set (502s-504s, etc.) includes three resistive components (R1-R3, R4-R6, R7-R9, etc.) of this nature;

at least one radio-frequency signal by-pass path (507), being between the side contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), from one side of the switch (SA1), and which (507) is characterized in that it (507) is considered to be the side commutation position (501p) of the slide switch (SA1), intended for the radio-frequency transmission line (507) with '0dB' attenuation level value (SA1v), i.e. having no attenuation or a very low attenuation level value, when it (507) is implemented in a form of the topological microstrip line path, and to the rest free commutation positions (502p-504p, etc.) the commutated attenuator sets (502s-504s, etc.) are placed with constantly increasing radio-frequency signal attenuation level values (SA1v) in respect of the side '0dB' commutation position (501p);

a segment of the printed circuit board (301), sufficient for inserting all the above mentioned circuit (300-500) components and parts of their groups; and

having the following features:

a group of the middle contact terminals (SA1c), presented one next to another and assigned to the first pole, of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1) is connected to the radio-frequency signal input terminal (508), and that

the other group of the middle contact terminals (SA1c), presented one next to another and assigned to the second pole, of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1) is connected to the radio-frequency signal output terminal (508), and that

the rest side contact terminal (SA1c) groups of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), belonging to the first and second poles and presented one next to another, are directly connected to the commutated attenuator sets (502s-504s, etc.), except for one side case, when from one side of the switch (SA1), between the side contact terminals (SA1c), presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), a radio-frequency signal by-pass path (507) is connected, characterized in that it (507) is considered to be the side commutation position of the slide switch (SA1), intended for the radio-frequency signal transmission line (507) with '0dB' attenuation value (SA1v), i.e. with no attenuation or very low attenuation value, when it (507) is implemented in a form of topological microstrip line path (507), and to the rest free commutation positions (502s-504s, etc.) the commutated attenuator sets (502s-504s, etc.) are placed with constantly increasing radio-frequency signal attenuation level values (SA1v) in respect of the side '0dB' commutation position (501p); and

are characterized in that

between all contact terminals (SA1c), on a place where they are presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), where the commutated attenuator set (502s-504s, etc.) is placed, straight under the housing of the slide switch, between the lower part of the housing and the printed circuit board, at least one constructive resistive component (R2,R5,R8, etc.) of '0402' or other similar overall size is connected, and if required, for frequency characteristic correction, other passive component of reactive nature is inserted.
The radio frequency circuit assembly as recited in claim 1 wherein said radio frequency circuit distinguished in that that between all contact terminals (SA1c), on a place where they are presented one against another and belonging to one pair or throw (SA1T), of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), where the commutated attenuator set (502s-504s, etc.) is placed, on the opposite side of the slide switch, on the side of the printed circuit board, between the same contact terminals, presented one against another and belonging to one pair or throw (SA1T), where the commutated attenuator set is placed (502s-504s, etc.), electrically is connected at least one resistive constructive component (R2,R5,R8, etc.) of '0402' or other similar overall size, and if required, for frequency characteristic correction, the other passive component of reactive nature is inserted.
The radio-frequency circuit assembly as recited in claim 1 wherein said radio frequency circuit distinguished in that that between the middle contact terminals (SA1c) of one group, belonging to the first pole and presented close to one another, of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), which are connected to the radio-frequency signal input terminal (508) and the middle contact terminals (SA1c) of the other group, belonging to the second pole and presented close to one another, of the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), which are connected to the radio-frequency signal output terminal (509), just under the housing of the slide switch, between the upper part of the housing and the printed circuit board, at least one of resistive and/or reactive nature constructive component of '0402' or other similar overall size is inserted.
The radio-frequency circuit assembly as recited in claim 3 wherein said that the radio-frequency circuit has the double-pole (SADP) multi-throw (501p-504p, etc.) slide switch (SA1), which can be implemented as a surface mount component and/or comprised of two separate parts which are distinguished for the polar contact groups connection in a separate manner.