EP3163776A1

EP3163776A1 - A low noise block downconverter circuit

Info

Publication number: EP3163776A1
Application number: EP15192664.9A
Authority: EP
Inventors: Hendrik Caron; Ladislav Jarkovsky; Stephen Deleu
Original assignee: Unitron NV
Current assignee: Unitron NV
Priority date: 2015-11-02
Filing date: 2015-11-02
Publication date: 2017-05-03

Abstract

There is described a low noise block downconverter circuit (10), wherein first stage low noise radio frequency amplifiers (32, 34), the next stage low noise radio frequency amplifiers (36, 38, 40), frequency mixers (50) and oscillators (62, 64) are arranged on a single printed circuit board (100). Preferably the frequency mixers (50) and the oscillators (62, 64) are arranged in a single integrated circuit (200). The printed circuit board (100) comprises an insulating substrate with a dissipation factor of 0,007 or higher at a frequency of 10GHz.

Description

Technical Field

The present invention generally relates to a low noise block downconverter or LNB, for example for receiving satellite TV signals. More particularly it relates to a low noise block downconverter circuit for use in such a LNB, which downconverts the radio frequency signal received from a feedhorn to an intermediate frequency signal for further distribution to receiving devices.

Background

It is known from for example http://www.qsl.net/va3iul/Files/RF-Microwave PCB Design and Layout.pdf , page 25 last paragraph, that radio frequency analog circuits require the use of printed circuit boards with high-end, expensive, high frequency laminates. A low noise block downconverter circuit for use in a LNB is a particular embodiment of such a radio frequency analog circuit, of which some components operate at frequencies of over 10GHz. These high end, high frequency laminates for PCBs often do not allow for a multilayer design, thereby complicating design of the PCB and increasing its overall size. Printed circuit boards with an FR-4 glass epoxy substrate are not considered suitable for use in such analog radio frequency applications. This is confirmed by table 2 on page 32, which does not list FR-4 among materials for analog radio frequency applications. This table 2 only lists types of printed circuit board substrates manufactured by Rogers corporation with a relative permittivity or dielectric constant Er at 10GHz of 3,0 or lower; or alternatively of 6,15 or higher; and a Loss Tangent or dissipation factor of 0,0035 or lower.
A further low noise block downconverter circuit is known from for example http://www.nxp.com/documents/application_note/AN11674.pdf. Such an embodiment makes use of an TFF1044HN integrated circuit manufactured by NXP Semiconductors. This integrated circuit comprises mixers, local oscillators, intermediate frequency amplifier stages, etc. This integrated circuit combined with an external set of radio frequency low noise amplifiers and corresponding band pass filters, as shown in Figure 3 of this document, is arranged on a single printed circuit board or PCB and in this way forms a low noise block downconverter circuit for use in universal Quad LNBs or a universal Quattro LNBs. Such an embodiment is suitable for receiving Ku band satellite signals in the frequency range of 10.70 GHz to 12.75 GHz. As stated in point 2.5 of this document it is clearly stated that this low noise block downconverter circuit or LNB circuit should be built with a single Rogers PCB. This means with a PCB comprising a dedicated, high frequency substrate, such as for example manufactured by Rogers corporation. From a mechanical point of view, such high frequency substrates, for example comprising a PTFE or ceramic substrate are less robust and more delicate then an FR-4 glass epoxy substrate. The cost of such dedicated Rogers PCBs or other high frequency PCBs is often a factor of five or more higher when compared to general purpose FR-4 PCBs.
A further low noise block downconverter circuit making use of an integrated circuit and a single PCB is for example known from CN202798740U . The integrated circuit used here is a RDA3560M integrated circuit manufactured by RDA microelectronics which comprises a CMOS integrated circuit for selectively downconverting two Ku band radio frequency signals to an L band intermediate frequency signal. This integrated circuit comprises for example a mixer and corresponding oscillator, an intermediate frequency amplifier, etc.
Still a further integrated circuit for use in such a low noise block downconverter circuit is the MxL801 manufactured by MaxLinear and for example known from http://www.maxlinear.com/maxlinear-delivers-turnkey-satellite-channel-stacking-solution-for-new-ultra-compact-d-odu-from-pbi/. The MxL801 integrates Ku-band down-conversion functionality on a single-chip integrated circuit comprising image rejection filtering, crystal oscillator and phase-locked loop and bias voltage generator for external low noise amplifiers. The MxL801 receives two RF input signals comprising a frequency range of 10.7 GHz to 12.75 GHz at dual Ku-band radio-frequency inputs. The MxL801 outputs two wideband IF signals comprising a frequency range of 200 MHz to 2350 MHz at dual wideband IF outputs. Such a MxL801 radio frequency integrated circuit or RF IC can for example be coupled with its IF outputs to the inputs of a MxL862 digital channel stacking system on chip. Such an integrated circuit integrates a 24-channel digital stacking switch, including DiSEqC and FSK communication modems and a microcontroller.
Alternative LNB circuits for use in an LNB are known from for example US2005/0219007 and EP1296411 . These LNB circuits make use of two printed circuit boards. A first printed circuit board comprises components of the LNB circuit such as the radio frequency low noise amplifiers, radio frequency filters, mixers, oscillators, etc. which operate on the radio frequency signal in a frequency range of 10GHz to 13 GHz. This first printed circuit board comprises a high frequency substrate such as for example a substrate manufactured by Rogers materials or comprising Polytetrafluoroethylene or PTFE. A second printed circuit board comprises a low-cost epoxy resin substrate such as FR-4 and only comprises components that need to handle the downconverted intermediate frequency signal in a frequency range of 0,9GHz to 2,5GHz as received from the first printed circuit board. Such an embodiment of LNB circuits making use of two printed circuit boards comprising substrates of different materials comprises several disadvantages. The first printed circuit board needs to be coupled to the second printed circuit board by means of a plurality of electrical connections. This complicates the manufacturing process and leads to an increased risk of errors during manufacturing. These interconnections also render the construction of the LNB circuit less robust and increase the risk of mechanical failure during use. Additionally as the different materials of the substrates of the different PCBs comprise different mechanical properties and will for example comprise different thermal expansion coefficients, this will result in a risk of corresponding stresses and loads, especially on the interconnections between both printed circuit boards, still further increasing the risk of failure during operation and reducing the service life of the LNB. Finally, as an LNB has become a low cost component, the cost of the high frequency PCB has become as high as 40% to 50% of the overall cost of the LNB.
There still exists a need for an LNB circuit that overcomes the abovementioned drawbacks and is able to provide for a simple and robust construction, which allows for an increased design flexibility and is less expensive.

Summary

According to a first aspect of the invention, there is provided a low noise block downconverter circuit, comprising:

at least one first stage low noise radio frequency amplifier configured to receive and amplify at least one corresponding radio frequency signal;
at least one next stage low noise radio frequency amplifier coupled to the at least one first stage low noise radio frequency amplifier such that at least one amplified radio frequency signal is received and amplified;
at least one frequency mixer and at least one local oscillator couplable to the at least one frequency mixer, the at least one frequency mixer coupled to the at least one next stage low noise radio frequency amplifier such that the at least one amplified radio frequency signal is received and downconverted to at least one intermediate frequency signal;
at least one intermediate frequency signal amplifier coupled to the at least one frequency mixer such that the intermediate frequency signal is received and amplified, wherein the at least one first stage low noise radio frequency amplifier, the at least one next stage low noise radio frequency amplifier, the at least one frequency mixer, the at least one oscillator and the at least one intermediate frequency amplifier are arranged on a single printed circuit board comprising an insulating substrate with a dissipation factor of 0,016 or higher at a frequency of 10GHz.

In this way, contrary to the beliefs of a skilled person, a cheap, robust PCB, which was previously believed unsuitable for use in an LNB circuit, is applied for use in an LNB circuit and surprisingly provides for an acceptable performance while drastically reducing cost and increasing design flexibility as for example multiple layers can be provided for.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the at least one frequency mixer, the at least one oscillator and the at least one intermediate frequency amplifier are arranged in a single integrated circuit.
In this way, surprisingly and in total contrast to the teachings of the prior art as generally accepted by a skilled person, the use of a woven fiberglass cloth and an epoxy resin binder as an insulating substrate for a single printed circuit board for the LNB circuit provides for a simple and robust LNB circuit. This is achieved by means of a synergetic effect of the single integrated circuit combined with such a PCB. As the radio frequency signal transported along the PCB is minimized by integration of several components which process this radio frequency signal into the integrated circuit, the negative effects of such a type of PCB on the radio frequency signal are reduced to acceptable levels, while such a type of PCB provides for a more robust and simple construction, which for example also more easily allows for a multi-layer type of PCB.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the insulating substrate comprises a woven fiberglass cloth and an epoxy resin binder.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the insulating substrate does not comprise Polytetrafluoroethylene and/or ceramic. This means that the PCB insulating substrate does not comprise any of these in quantities substantial enough to provide for a detectable impact on the dissipation factor.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the insulating substrate consists of a woven fiberglass cloth and an epoxy resin binder.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the epoxy resin binder is flame retardant.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the insulating substrate is an FR-4 insulating substrate.
These embodiments allow for a simple, cheap, robust and easy to manufacture LNB circuit.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the insulating substrate comprises at least one of the following parameters:

a relative permittivity or a dielectric constant in the range of 4 to 5, preferably 4.4 plus or minus 5% at a frequency of 10GHz;
a thermal coefficient of the dielectric constant of 150ppm per °C change in temperature.

Such parameters for the PCB are acceptable, even for the radio frequency signal, because of the synergetic effect with the single integrated circuit.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the first stage low noise amplifier and/or the at least one next stage low noise radio frequency amplifier is also arranged in the integrated circuit.
In this way the signal path for the radio frequency signal along the PCB is still further reduced.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that characterised in that it further comprises at least one radio frequency bandpass filter respectively arranged in between one of the at least one next stage low noise radio frequency amplifier and one of the at least one frequency mixer.
Such filters could for example function to select a specific frequency range and/or reduce the risk for interference of undesired mirror frequencies in the downconverted intermediate frequency signal.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the bandpass filter is also arranged in the integrated circuit.
In this way the signal path for the radio frequency signal along the PCB is still further reduced.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the first stage low noise radio frequency amplifiers are not arranged in the integrated circuit.
These first stage radio frequency low noise amplifiers or RF LNA are preferably a Pseudomorphic High Electron Mobility Transistor or pHEMT or alternatively another suitable type of transistor, such as for example a Hetero Junction Field Effect Transistor, that is able to operate at higher frequencies, such as for example RF frequencies in use in an LNB for reception of satellite TV signals. Such transistors are able to provide for an initial stage of amplification of the radio frequency signal with a minimum level of noise. However such type of transistors make use of materials such as for example GaAs, AlGaAs, In, etc. which are not compatible with the materials used in the integrated circuit, or would at least complicate its design and manufacturing and decrease its robustness.
According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the radio frequency signals comprise a frequency range according to one or more of the following:

C-band or a frequency range from 3,4GHz to 4,2GHz;
Ku-band or a frequency range from 10,7GHz to 12,75GHz;
Ka-band or a frequency range from 18.3GHz to 18.8Ghz, and

L-band or a frequency range from 0,9GHz to 2,3GHz;
a wideband intermediate frequency or a frequency range from 0,2GHz to 2,350GHz;
a frequency range of up to 3GHz.

According to an embodiment there is provided a low noise block downconverter circuit, characterised in that the low noise block downconverter circuit further comprises a control module configured to:

selectively connect one of two first stage low noise radio frequency amplifiers to one next stage low noise radio frequency amplifier; or
selectively power one of two first stage low noise radio frequency amplifiers, both first stage low noise radio frequency amplifiers being connected to one next stage low noise radio frequency amplifier.

Especially, according to the latter option there is a minimum of noise introducing elements inserted into the signal path of the radio frequency signal.
According to an embodiment the control module is also arranged in the integrated circuit.
According to a second aspect of the invention, there is provided a low noise block downconverter assembly for a satellite signal comprising at least one low noise block downconverter circuit, characterised in that the low noise block downconverter assembly further comprises a feedhorn for receiving a satellite signal, the feedhorn coupled to the low noise block downconverter circuit such that the at least one corresponding radio frequency signals are provided to the at least one first stage low noise radio frequency amplifier.
According to an embodiment, there is provided a low noise block downconverter assembly for a satellite signal comprising at least one low noise block downconverter circuit according to the first aspect of the invention, characterised in that the low noise block downconverter assembly further comprises a feedhorn for receiving a satellite signal, the feedhorn coupled to the low noise block downconverter circuit such that the two corresponding radio frequency signals of two different polarisations are provided to the two first stage low noise radio frequency amplifiers.
According to a third aspect of the invention there is provided a method of manufacturing the low noise block downconverter circuit according to the first aspect of the invention, characterised in that the method comprises the steps of:

providing the single printed circuit board (100) comprising the insulating substrate with a dissipation factor of 0,007 or higher at a frequency of 10GHz,
arranging the at least one first stage low noise radio frequency amplifier (32, 34), the at least one next stage low noise radio frequency amplifier (40), the at least one frequency mixer (50), the at least one oscillator (62, 64) and the at least one intermediate frequency amplifier (70) on the single printed circuit board (100).

According to a preferred embodiment the method comprises the step of:

providing the single printed circuit board (100) comprising the insulating substrate with a dissipation factor of 0,012 or higher at a frequency of 10GHz, preferably 0,016 or higher at a frequency of 10GHz.

According to an embodiment the method comprises the steps of:

providing the single printed circuit board comprising the insulating substrate comprising a woven fiberglass cloth and an epoxy resin binder,
arranging the single integrated circuit on the single printed circuit board;
arranging the two first stage low noise radio frequency amplifiers on the single printed circuit board.

In this way the robust low noise block downconverter circuit can be manufactured in a simple and efficient way.

Brief Description of the Drawings

Figure 1 illustrates an embodiment of the low noise block downconverter circuit according to the invention;
Figures 2 and 3 illustrate further embodiments of the low noise block downconverter circuit, alternative to that of Figure 1;
Figures 4 respectively show the noise figure of the embodiment of Figure 1 in comparison to a prior art low noise block downconverter circuit.

Detailed Description of Embodiment(s)

In a typical satellite signal distribution system, one or more satellite dishes are provided for capturing the high frequency or radio frequency or RF satellite signal transmitted by one or more satellites. The parabolic shape of the satellite dish reflects the focal point of the dish. A feedhorn is mounted at or near this focal point and feeds the RF satellite signal by means of a suitably connected waveguide to a low-noise block downconverter or LNB. Often the LNB and feedhorn are integrated into an LNB assembly. The LNB converts the radio frequency or RF satellite signals from electromagnetic waves or radio waves to electrical signals and shifts the signals from for example the radio frequency C-band, Ku-band, Ka-band, etc. to intermediate frequency IF signals, for example in the L-band range, wideband IF range, etc. which are more suitable for further distribution, for example by means of coaxial cables for further distribution to the receiving devices or tuners, such as for example Set Top Boxes or STB, Personal video recorders or PVR, etc.
The high frequency RF satellite signals and their corresponding downconverted IF signals comprise a plurality of smaller frequency bands, which are generally referred to as transponders or channels, each containing one or more TV, radio or data channels. For example, in Europe, a Ku band RF satellite signal with a frequency band from 10.7 to 12.75 GHz, comprising 2 polarisations, for example a vertical and a horizontal polarisation, is used for direct broadcast satellite services such as those carried by the Astra satellites. This RF satellite signal for example comprises a plurality of transponders with a bandwidth of 36MHz of which the center frequencies are spaced 39Mhz apart. The RF satellite signal is conventionally downconverted by means of a universal LNB to one or more IF signals comprising a bandwidth ranging from about 0.95GHz to 2.15GHz. A universal LNB allows for selection or combined distribution of a horizontal low band; a horizontal high band, a vertical low band; and a vertical high band. Each of these IF signals comprising the respective plurality of transponders of the respective downconverted RF satellite signal frequency range, for example 24 transponders. The IF signal is distributed by means of coaxial cables to receiving devices such as for example Set Top Boxes or STB. According to some embodiments more than one RF satellite signal is received, for example by means of a plurality of satellite dishes. According to some embodiments, for example in a multiple dwelling context, additional distribution devices are often provided for distributing the received IF signals to the inputs of the receiving devices. According to still further embodiments, which will be described in further detail below with reference to Figure 2, the RF satellite signal, for example comprising one or more Ku band signals in the frequency range of 0,95GHz - 2,15GHz, could be downconverted in their entirety to one or more corresponding wideband intermediate frequency signal, for example with a frequency range of 0,2GHz to 2,35GHz or alternatively for example 0,29GHz to 2,34GHz.
Figure 1 shows an embodiment of a low noise block downconverter assembly 1 for a satellite signal. As schematically shown the low noise block downconverter assembly 1 comprises a feedhorn 2 for receiving a satellite signal. As schematically shown the feedhorn 2 is coupled to the low noise block downconverter circuit 10 such that the two corresponding radio frequency signals 22, 24 of two different polarisations are provided to two first stage low noise radio frequency amplifiers 32, 34. These two different polarisations could for example relate to a vertical and horizontal polarisation of a Ku band satellite TV signal. However it is clear that alternative embodiments are possible, which for example relate to two radio frequency or RF satellite signals with right hand side and left hand side circular polarisations.
As further shown the low noise block downconverter circuit 10 also comprises an integrated circuit 200, which will be explained in further detail below. As shown, according to this embodiment, preferably the first stage low noise radio frequency amplifiers 32, 34 are not arranged in the integrated circuit 200. These first stage radio frequency low noise amplifiers or RF LNA 32, 34 are preferably a Pseudomorphic High Electron Mobility Transistor or pHEMT or another suitable type of transistor, such as for example a suitable Field Effect Transistor or FET, a Hetero Junction FET or HJ-FET, etc. that is able to operate with low noise at radio frequencies for example in the Ku band, for example in the frequency range of 10,7GHz to 12,75GHz. As already mentioned above, such transistors are able to provide for an initial stage of amplification of these radio frequency signals 22, 24 with a minimum level of noise. This is advantageous as the radio frequency signal received from the feed horn 2 is typically very weak and very sensitive to noise at this stage. After this first stage of radio frequency amplifiers the subsequent effect of noise on the amplified radio frequency signals 22, 24 will be several factors less. In order to achieve such a first stage RF LNA 32, 34, preferably there is made use of transistors that make use of materials such as for example GaAs, AlGaAs, In, etc. Typically three to four stages of amplification are required in order to achieve a typical gain in the range of 50dB to 60dB. As will be described in further detail below, next to the first stage RF LNA, according to this embodiment there is also provided second stage RF LNA and an IF amplifier, thus resulting in three stages of amplification, namely two stages of RF amplification and one stage of IF amplification. When typically three to four stages of amplification are provided, this is thus realised by one or more stages of RF amplification and one or more stages of IF amplification leading to a combined number of three or four stages of amplification.
According to the embodiment of Figure 1 a second stage low noise radio frequency amplifier 40 is coupled to the first stage low noise radio frequency amplifiers 32, 34. As will be explained in further detail below a control module 300 will select one of the first stage low noise radio frequency amplifiers 32, 34. Both first stage low noise radio frequency amplifiers 32 are connected to the second stage radio frequency low noise amplifier 40, however only the one that is selected by the control module 300 will be operative and will provide its amplified RF signal 22, 24 to the second stage RF LNA 40. It is clear that in this way the second stage RF LNA 40 selectively receives a selected one of the two amplified RF signals 22, 24 from the first stage RF LNAs 32, 34. The RF LNA 40 will further amplify this received RF signal 22, 24. According to this embodiment the RF LNA 40 is arranged in the integrated circuit 200, however it is clear that alternative embodiments are possible in which for example this second stage LNA is a discrete component arranged outside the integrated circuit 200. As will be clear to a person skilled in the art, the control module 300 can for example be operated in function of a suitable control signal received from a receiver device such as an STB at an intermediate frequency output connector 90 of the LNB assembly 1. This control signal could for example be derived from a predetermined DC voltage level provided by the receiver device, for example 13V for selection of vertical or right hand polarisation, and 18V for selection of the horizontal or left hand polarisation. Alternative control signals could be provided, such as for example selection commands generated by the receiver devices encoded according to a protocol based on Digital Satellite Equipment Control or DiSEqC. It is clear that alternative protocols are available such as for example FSK, which is for example used in the US, or any other suitable alternative protocol. With such protocols data signals and power can be transmitted and received over a coaxial cable without interfering with the intermediate frequency signal 60. According to the state of the embodiment shown, the control module 300 has activated the first stage RF LNA 32 and deactivated RF LNA 34, thereby selectively providing the amplified RF signal 22, for example of the horizontal polarisation, to second stage RF LNA 40.
As further shown, the embodiment of Figure 1 the low noise block downconverter circuit 10 further comprises a radio frequency bandpass filter 80. This radio frequency bandpass filter 80 is arranged in between the second stage RF LNA 40 and a frequency mixer 50. According to a particular embodiment the RF bandpass filter 80 could for example comprise a bandpass frequency range of for example the European Ku band RF satellite signal with a frequency band from 10.7 to 12.75 GHz. It is clear that such an RF bandpass filter 80, is preferred as it will reduce the risk of interference of undesired mirror frequencies in the downconverted intermediate frequency signal as generated by the subsequent frequency mixer 50. As shown, also the bandpass filter 80 is arranged in the integrated circuit 200.
As further shown, according to the embodiment of Figure 1 the frequency mixer 50 is selectively couplable to two local oscillators 62, 64. A first local oscillator LO1 62 operates for example at a frequency of 9,75GHz and a second local oscillator LO2 64 operates at a frequency of for example 10,6GHz. As shown the control module 300 enables to selectively couple one of these local oscillators 62, 64 to the frequency mixer 50 by means of a suitable switch 52. As already mentioned above this allows the frequency mixer 50 for example to select a low frequency band or a high frequency band for downconversion by the frequency mixer 50. When, in the state of the embodiment shown in Figure 1, the frequency mixer 50 is coupled to LO1 62 operating at a frequency of 9,75GHz, then the low frequency band of 10,7GHz to 11,7GHz of the selected horizontal RF signal 22 will be selected for downconversion by the frequency mixer 50. Alternatively, when LO2 64 operating at a frequency of 10,6GHz would have been selected, then the high frequency band of 11,7GHz to 12,75GHz of the horizontal RF signal 22 would have been selected for downconversion by the frequency mixer 50. It is clear, similar as explained above, that the control module 300 is able to perform such a selection in function of suitable control signals received from a receiving device, for example via IF output connector 90. Such control signals could for example be the presence or absence of a 22kHz tone, a suitable DiSEqC command, or any other suitable control signal. The frequency mixer 50 thus receives the amplified RF signal 22 from the second stage RF LNA 40 via the bandpass filter 80 and downconverts it to an intermediate frequency signal 60 in the L-band, for example in the frequency range of 0,95GHz to 2,15GHz. According to the embodiment shown, the frequency mixer 50 and the local oscillators 62, 64 are arranged in the integrated circuit 200.
As further shown, the LNB circuit 10 further comprises an intermediate frequency signal amplifier 70 which receives the intermediate frequency signal 60 from the frequency mixer 50. The IF signal amplifier 70 amplifies this IF signal 60 and for example provides it to a suitable IF output connector 90, for example for further distribution to one or more receiver devices by means of coaxial cables. According to this embodiment the IF signal amplifier 70 is also arranged in the integrated circuit 200.
As shown the two first stage low noise radio frequency amplifiers 32, 34 and the integrated circuit 200 are arranged on a single printed circuit board 100. This single printed circuit board 100 comprises an insulating substrate comprising a woven fiberglass cloth and an epoxy resin binder. Preferably the insulating substrate is flame retardant and is for example an FR-4 insulating substrate. It should be clear that this means that the single printed circuit board 100 is not a special high frequency printed circuit board 100 and does not comprise an insulating substrate that comprises a Polytetrafluoroethylene substrate or a ceramic substrate. According to a preferred embodiment the insulating substrate of the single printed circuit board 100 consists of a woven fiberglass cloth and an epoxy resin binder. Such an insulating substrate comprising one or more parameters like: a relative permittivity or a dielectric constant in the range of 4 to 5, for example 4,1 to 4,5, for example 4,2 at a frequency of 10GHz; a thermal coefficient of the dielectric constant of 150ppm per °C change in temperature, were previously not considered suitable for use with RF signals 22, 24 in the context of an LNB circuit. Additionally, according to some embodiments, such PCBs could comprise an insulating substrate comprising a relative permittivity or a dielectric constant with a tolerance of at least plus or minus 3%, for example plus or minus 10%, which were previously not considered suitable for use with RF signals 22, 24 in the context of an LNB circuit. However, the synergetic effect with the integrated circuit 200 which reduces the signal path for the RF signal 22, 24 along the PCB 100 surprisingly allows for the use of this type of PCB 100 successfully. It is clear that still further alternative embodiments for the insulating substrate are possible, as long as in general it comprises a dissipation factor of 0,007 or higher at a frequency of 10GHz, which were previously not considered suitable for use with RF signals in the context of an LNB circuit. Preferably, the dissipation factor is 0,012 or higher at a frequency of 10GHz, for example 0,016 or higher at a frequency of 10GHz as especially PCBs comprising such an insulating substrate were previously not considered suitable for use with RF signals in the context of an LNB circuit and provide for a very simple, robust and cheap LNB circuit. Page 35 of a presentation dated 2012 and titled "Points to be considered when choosing a laminate" by Rogers Corporation, clearly shows the link between the cost factor and dissipation factor of a PCB. It shows that Tier 1 PCBs with a dissipation factor of 0,020 or more are the cheapest. Tier 2 PCBs, which have a dissipation factor in the range of 0,010 to 0,020, and Tier 3 PCBs, which have dissipation factor in the range of 0,007 to 0,010 have a cost factor that is up to 1,5 times that of the Tier 1 PCBs. In general, this thus means that, counter to previous beliefs of the man skilled in the art, according to the invention, preferably Tier 1 PCBs can be used and optionally Tier 2 or Tier 3 PCBs can be used, which do not lead to an increase in cost with a factor higher than 2 when compared to Tier 1 PCBs. As shown on page 35 of the abovementioned presentation, PCBs with a dissipation factor below 0,007, this means Tier 4, 5 and 6 PCBs and especially Tier 5 and 6 PCBs with a dissipation factor respectively lower than 0,005 and 0,003 lead to an increase in cost with a factor higher than 2, for example a cost factor of 3 up to 15 when compared to Tier 1 PCBs.
It is clear that alternative embodiments to the one described above are possible, as long as in general the radio frequency signals 22, 24 comprise a frequency range according to the C-band, Ku-band, Ka-band, etc. and the intermediate frequency signal 60 comprises a frequency range according the L-band, wideband IF or a frequency range of up to 3GHz.
According to still a further alternative embodiment, instead of the selective activation of the first stage FR LNAs 32 and 34 above, instead the control module 300 could for example selectively connect the second stage RF LNA 40 to one of the first stage RF LNAs 32, 34, and thus selectively disconnect the second stage RF LNA 40 from the other first stage RF LNA. This could for example be realised by means of a suitable RF switch under control of the control module 300.
Figures 2 and 3 show alternative embodiments similar to the embodiment of Figure 1. Similar elements have been denoted with similar references and generally function in a similar way as described above. Different from the embodiment of Figure 1, as shown in Figure 2, RF signals 22, for example the horizontal polarisation of the satellite signal, is provided via a first stage RF LNA 32 and a second stage RF LNA 36 to a third stage RF LNA 40. According to the embodiment shown in Figure 2; the first stage RF LNA 32 and second stage RF LNA 36 are arranged outside the integrated circuit 200. As shown, the third stage RF LNA 40 is arranged in the integrated circuit 200. The amplified RF signal 22 is provided via the filter 80 to the frequency mixer 50. The frequency mixer 50 cooperates with its local oscillator 62 to downconvert the RF signal 22 to the IF signal 66. The integrated circuit 200 could for example be embodied as an MxL801 RF IC mentioned above and frequency translate a horizontal Ku band RF signal 22 to a wideband IF signal 66 with a frequency range of 0,2GHz to 2, 35GHz. As further shown, similar as described above, also the vertical RF signal 24 is downconverted, after amplification by three stages of LNAs 34, 38, 40, by a corresponding frequency mixer 50 to an IF signal 68, for example a wideband IF signal. Both these IF wideband signals 60, according to this embodiment are provided to a further integrated circuit, for example a Channel Stacking Switch or CSS, such as for example in the form of an MxL862 digital channel stacking system on chip referred to above. As shown, this CSS integrated circuit 210, under control of the receiving devices or in function of a predefined configuration will select a suitable number of channels from both IF wideband signals 60 received from the RF IC 200 and will provide these to a plurality of IF output connectors 90. It is clear that, as shown, the RF IC 200 according to such an embodiment does not require a control module 300 to be present as the respective RF signal can be frequency translated in its entirety to a corresponding IF signal. All required control functionality can be provided into the CSS integrated circuit 210, which operates exclusively in the intermediate frequency range.
Figure 3 shows still a further embodiment, similar to that of Figure 2. The main differences are that all three stages of RF LNAs 32, 34, 36, 38, 40 are all integrated into the RF IC 200. Further also there is not present a further integrated circuit such as for example the CSS integrated circuit 210. Both IF signals 60, 66, 68 are provided directly to two corresponding IF output connectors 90 for further distribution, for example by means of suitable coaxial cables.
It is clear that still further embodiments are possible comprising any suitable combination of at least one first stage RF LNA and at least one next stage LNAs. This means there could be any suitable combination and number of first stage, second stage, third stage, etc RF LNAs. It is clear that according to alternative embodiments any number or stages of these RF LNAs could be arranged outside or inside the RF IC 200.
According to still further embodiments it is clear that the LNB assembly 1 could comprise other or still further additional circuits, such as for example a switching matrix, a channel stacking switch or CSS, etc. arranged on the PCB 100 and/or arranged on one or more other PCBs. According to still further embodiments the control module 300 could for example at least partially be arranged on another PCB than the PCB 100. It is clear that still further alternative embodiments are possible as long as in general the next stage low noise radio frequency amplifier 40, the frequency mixer 50, the at least one oscillator 62, 64 and the intermediate frequency amplifier 70 are arranged in a single integrated circuit 200.
Figures 4 respectively show the noise figure of the embodiment of Figure 1 comprising a single PCB 100 with an FR-4 insulating substrate in comparison to a prior art low noise block downconverter circuit comprising a dedicated high frequency PCB manufactured by Rogers corporation and known under the tradename RO4003. The FR-4 PCB comprises a dielectric constant of 4,3 and the Rogers PCB comprises a dielectric constant of 3,38. The FR-4 PCB comprises a dissipation factor of 0,0175 and the Rogers PCB comprises a dissipation factor of 0,0027. As shown both the noise figure and the gain of the FR-4 PCB according to the embodiment of Figure 1 only divert a surprisingly low amount from the prior art embodiment of the Rogers PCB. The use of this type of FR-4 PCB enables to reduce the cost of the PCB for the LNB circuit to be reduced by a factor of four, while allowing for a more robust and flexible design, which contrary to existing beliefs of the man skilled in the art provides for an acceptable performance as an RF LNB circuit.
Although the present invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied with various changes and modifications without departing from the scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the scope of the claims are therefore intended to be embraced therein.
It will furthermore be understood by the reader of this patent application that the words "comprising" or "comprise" do not exclude other elements or steps, that the words "a" or "an" do not exclude a plurality, and that a single element, such as a computer system, a processor, or another integrated unit may fulfil the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned. The terms "first", "second", third", "a", "b", "c", and the like, when used in the description or in the claims are introduced to distinguish between similar elements or steps and are not necessarily describing a sequential or chronological order. Similarly, the terms "top", "bottom", "over", "under", and the like are introduced for descriptive purposes and not necessarily to denote relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the invention are capable of operating according to the present invention in other sequences, or in orientations different from the one(s) described or illustrated above.

Claims

A low noise block downconverter circuit (10), comprising:
- at least one first stage low noise radio frequency amplifier (32, 34) configured to receive and amplify at least one corresponding radio frequency signal (22, 24);

- at least one next stage low noise radio frequency amplifier (36, 38, 40) coupled to the at least one first stage low noise radio frequency amplifier (32, 34) such that at least one amplified radio frequency signal (22, 24) is received and amplified;

- at least one frequency mixer (50) and at least one local oscillator (62, 64) couplable to the at least one frequency mixer (50), the at least one frequency mixer (50) coupled to the at least one next stage low noise radio frequency amplifier (36, 38, 40) such that the at least one amplified radio frequency signal (22, 24) is received and downconverted to at least one intermediate frequency signal (60),
wherein the at least one first stage low noise radio frequency amplifier (32, 34), the at least one next stage low noise radio frequency amplifier (40), the at least one frequency mixer (50) and the at least one oscillator (62, 64) are arranged on a single printed circuit board (100) comprising an insulating substrate with a dissipation factor of 0,007 or higher at a frequency of 10GHz.
A low noise block downconverter circuit according to claim 1, characterised in that the insulating substrate comprises a dissipation factor of 0,012 or higher at a frequency of 10GHz, preferably 0,016 or higher at a frequency of 10GHz.
A low noise block downconverter circuit according to claim 1 or 2, characterised in that the at least one frequency mixer (50) and the at least one oscillator (62, 64) are arranged in a single integrated circuit (200).
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the insulating substrate comprises a woven fiberglass cloth and an epoxy resin binder.
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the insulating substrate does not comprise Polytetrafluoroethylene and/or ceramic.
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the insulating substrate consists of a woven fiberglass cloth and an epoxy resin binder.
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the insulating substrate is an FR-4 insulating substrate; and/or the insulating substrate comprises a relative permittivity or a dielectric constant with a tolerance of at least plus or minus 3%.
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the first stage low noise amplifier (32, 34) and/or the at least one next stage low noise radio frequency amplifier (40) is also arranged in the integrated circuit (200).
A low noise block downconverter circuit according to any of the preceding claims, characterised in that it further comprises:
- at least one radio frequency bandpass filter (80) respectively arranged in between one of the at least one next stage low noise radio frequency amplifier (40) and one of the at least one frequency mixer (50); and/or

- at least one intermediate frequency signal amplifier (70) coupled to the at least one frequency mixer (50) such that the intermediate frequency signal (60) is received and amplified.
A low noise block downconverter circuit according to claim 9, characterised in that the bandpass filter (80) and/or the intermediate frequency signal amplifier (70) are also arranged in the integrated circuit (200).
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the first stage low noise radio frequency amplifiers (32, 34) are not arranged in the integrated circuit (200).
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the radio frequency signals (22, 24) comprise a frequency range according to one or more of the following:
- C-band or a frequency range from 3,4GHz to 4,2GHz;

- Ku-band or a frequency range from 10,7GHz to 12,75GHz;

- Ka-band or a frequency range from 18.3GHz to 18.8Ghz, and
in that the intermediate frequency signal (60) comprises a frequency range according to one or more of the following:
- L-band or a frequency range from 0,9GHz to 2,3GHz;

- a wideband intermediate frequency or a frequency range from 0,2GHz to 2,350GHz;

- a frequency range of up to 3GHz.
A low noise block downconverter circuit according to any of the preceding claims, characterised in that the low noise block downconverter circuit (10) further comprises a control module (300) configured to:
- selectively connect one of two first stage low noise radio frequency amplifiers (32, 34) to one next stage low noise radio frequency amplifier (40); or

- selectively power one of two first stage low noise radio frequency amplifiers (32, 34), both first stage low noise radio frequency amplifiers (32) being connected to one next stage low noise radio frequency amplifier (40).
A low noise block downconverter assembly (1) for a satellite signal comprising at least one low noise block downconverter circuit (10) according to any of the preceding claims, characterised in that the low noise block downconverter assembly (1) further comprises a feedhorn (2) for receiving a satellite signal, the feedhorn (2) coupled to the low noise block downconverter circuit (10) such that the at least one corresponding radio frequency signals (22, 24) are provided to the at least one first stage low noise radio frequency amplifier (32, 34).
A method of manufacturing the low noise block downconverter circuit according to any of the claims 1 to 14, characterised in that the method comprises the steps of:
- providing the single printed circuit board (100) comprising the insulating substrate with a dissipation factor of 0,007 or higher at a frequency of 10GHz,

- arranging the at least one first stage low noise radio frequency amplifier (32, 34), the at least one next stage low noise radio frequency amplifier (40), the at least one frequency mixer (50) and the at least one oscillator (62, 64) on the single printed circuit board (100).