Self-adaptive frequency band-pass filtering device in microwave signal transceiver

• US 20030100272A1
• Filed: 12/12/2002
• Published: 05/29/2003
• Est. Priority Date: 06/26/2000
• Status: Active Grant

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Gilberton, Philippe, Denis, Bernard
• Granted Patent: US 7,082,294 B2
• Time in Patent Office: Days
• US Class Current: 455/80
• CPC Class Codes: H03J 2200/01 Circuitry controlling the selecting or switching action
• CPC Class Codes: H03J 5/244 using electronic means

Abstract

The present invention relates to a self-adaptive band-pass filtering device in a microwave signal transmitter and/or receiver, the receiver being connected to a microwave signal receiving antenna (1) connected to the input of a low-noise amplifier (2), a mixer (4) that receives, on the one hand, the output signal of the low-noise amplifier (2) and, on the other hand, the signal from a frequency synthesizer (5), characterized in that the self-adaptive filtering device (3) comprises, upstream of the amplifier (2), on the one hand, at least one filtering means (300, 31, 32) having at least two different frequency bands and, on the other hand, means (8, 33, 34) for selecting either a filtering means (31, 32) or one of the frequency bands depending on the frequency of the signal to be received.

Claims

1. Self-adaptive band-pass filtering device in a microwave signal transmitter and/or receiver, the receiver being connected to a microwave signal receiving antenna (1) connected to the input of a low-noise amplifier (2), a mixer (4) that receives, on the one hand, the output signal of the low-noise amplifier (2) and, on the other hand, the signal from a frequency synthesizer (5), characterized in that the self-adaptive filtering device (3) comprises, upstream of the amplifier (2), on the one hand, at least one filtering means (300, 31, 32) having at least two different frequency bands and, on the other hand, means (8, 33, 34) for selecting either a filtering means (31, 32) or one of the frequency bands depending on the frequency of the signal to be received.

2. Self-adaptive band-pass filtering device according to claim 1, characterized in that the filtering means comprise two filters (31, 32) and the selection means comprise a pair of microwave switches (33, 34) switching between two states, the said pair of switches being placed on each side of each band-pass filter (31, 32), so that, in a first state of the pair of switches (33, 34) the signal received by the antenna (1) is filtered by the first filter (31) and in a second state of the pair of switches (33, 34) the signal received by the antenna is filtered by the second filter (32).

3. Self-adaptive band-pass filtering device according to claim 1, characterized in that the two filters (31, 32) are intended for filtering a first frequency band (B1) and a second frequency band (B2), respectively.

4. Self-adaptive band-pass filtering device according to claim 2 or 3, characterized in that the frequency bands of the filtering means (31, 32) are separated.

5. Self-adaptive band-pass filtering device according to claim 1, characterized in that the filtering means comprise a filter (30) based on microstrip lines (300), each microstrip line of which is divided into two separate portions (301, 302) by the switching means (33′

), each of the first and second portions (301, 302) of the microstrip lines (300) being of a length defined so that when the switching means allow the received signal to pass, by coupling between microstrip lines, only into the first portion (301) the filter is tuned to a first frequency band, and when the switching means allow the signal to pass, by coupling between microstrip lines, into the first and second portions (301, 302) the filter (30) is tuned to the second frequency band.

6. Self-adaptive band-pass filtering device according to one of claims 2 to 5, characterized in that the change of state of the switches (33, 33′

, 34) of the selection means is triggered by a control means (8) associated with the frequency synthesizer (5) so that when the frequency imposed by the frequency synthesizer (5) lies within a first frequency band B1 of the filtering means (30, 31, 32) the control means (8) delivers a signal for making the switches (33, 33′

, 34) pass into the first state, and when the frequency imposed by the frequency synthesizer (5) lies within a second frequency band B2 of the filtering means (30, 31, 32) the control means (8) delivers a signal for making the switches (33, 33′

, 34) pass to the second state.

7. Self-adaptive band-pass filtering device according to claim 5 or 6, characterized in that the control means comprises a comparator (8), a first input (81) of which is connected via a buffer stage (9) to the frequency synthesizer (5) in order to receive the voltage-converted image of the frequency produced by the frequency synthesizer (5) and a second input (82) of which receives a defined reference voltage (V_ref).

8. Self-adaptive band-pass filtering device according to claim 5 or 6, characterized in that the control means comprises a comparator (8), a first input (81) of which is connected to a processing circuit (35) intended to deliver a voltage-converted image either of the frequency generated by the voltage-controlled oscillator (6) or of the frequency of the microwave signal received by the antenna (1).

9. Self-adaptive band-pass filtering device according to claim 7, characterized in that the processing circuit (35) comprises a phase/frequency comparator (351), a first input of which receives a signal generated by a fixed-frequency oscillator (350), the second input of the phase/frequency comparator (351) is connected to a switch (36) controlled by the microprocessor (7), making it possible to connect the second input either, in a first position (P1), to the output of the voltage-controlled oscillator (6) or, in a second position (P2), to a coupler (37) delivering an image of the frequency of the signals received on the antenna (1), and the second input (82) of the comparator (8) receives a defined reference voltage.

10. Self-adaptive band-pass filtering device according to claim 2, taken in combination with one of claims 6 to 9, characterized in that each switch (33, 34) comprises a pair of high-speed diodes (33.1, 33.2, 34.1, 34.2) mounted in series so that a first pair of diodes (33.1, 33.2) is mounted between the antenna (1) and the two filters (31, 32) and the second pair of diodes (34.1, 34.2) is mounted between the low-noise amplifier (2) and the two filters (31, 32).

11. Self-adaptive band-pass filtering device according to claim 10, characterized in that the anode of the first diode (33.1, respectively 34.1), connected via its cathode to the first filter (31), and the cathode of the second diode (33.2, respectively 34.2), connected via its anode to the second filter (32), of the first and second pair of diodes respectively are connected, on the one hand, to the antenna (1) and to the input of the low-noise amplifier (2) respectively and, on the other hand, to the output of the comparator (8) via the two links (83, 84) which then each include a shock inductor (830, 840), the cathode of the first diode (33.1, respectively 34.1) and the anode of the second diode (33.2, respectively 34.2) of each pair of diodes being also connected to earth through the shock inductor (330.1, 340.1, 331.1, 341.1).

12. Self-adaptive band-pass filtering device according to claim 5, taken in combination with one of claims 6 to 9, characterized in that the microwave switches of each microstrip line of the filter (30) include a diode (33′

) mounted in series between the two portions (301, 302) of the microstrip lines, the cathode of each diode (33′

) is connected to a first end of the first portion (301) of the microstrip lines (300), the second end of which is connected to earth, and the anode of each diode (33′

) is connected to a first end of the second portion (302) of the microstrip lines, the second end of which is connected to the output of the control means (8).