Radio frequency tuner front end and tuner

• US 20030078018A1
• Filed: 09/20/2002
• Published: 04/24/2003
• Est. Priority Date: 09/25/2001
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Mudd, Mark Stephen John, Cowley, Nicholas Paul
• Granted Patent: US 7,437,133 B2
• Time in Patent Office: Days
• US Class Current: 455/150.1
• CPC Class Codes: H03J 5/244 using electronic means

Abstract

A front end for a radio frequency tuner, for example for connection to a cable distribution network, including an input connected to a signal path comprising an LNA connected via an AGC stage to a signal splitter. The input path has a bandwidth sufficiently wide to pass all of the channels in an input signal and has a substantially constant voltage standing wave ratio over the bandwidth. The splitter supplies identical signals to several filtering paths, each of which comprises a fixed filter. The paths are selectable one at a time and the filters divide the input frequency band into a plurality of contiguous or slightly overlapping sub-bands. The output of the front end is supplied to, for example, a double conversion arrangement comprising an upconverter and a downconverter with first and second IF filters.

Claims

1. A radio frequency tuner front end, comprising:

an input for receiving an input signal in an input band containing a plurality of channels;

a plurality of filtering paths arranged to receive said input signal and having fixed frequency responses for dividing said input band into a plurality of sub-bands, each of which contains a plurality of said channels;

a signal path between said input and said filtering paths having a bandwidth sufficiently wide to pass said input band and a substantially constant voltage standing wave ratio over said bandwidth; and

a selecting arrangement for enabling any one of said filtering paths at a time to supply a filtered signal.

2. A front end as claimed in claim 1, in which ratios of an upper frequency limit to a lower frequency limit of said sub-bands are substantially equal to each other.

3. A front end as claimed in claim 2, in which said ratios are substantially equal to two.

4. A front end as claimed in claim 1, in which adjacent ones of said sub-bands are contiguous.

5. A front end as claimed in claim 1, in which adjacent ones of said sub-bands overlap.

6. A front end as claimed in claim 1, comprising two filtering paths.

7. A front end as claimed in claim 1, in which each of said filtering paths has a bandpass filtering response.

8. A front end as claimed in claim 6, in which said filtering paths comprise a lower path having a low pass filtering response and an upper path having a high pass filtering response.

9. A front end as claimed in claim 1, in which a first of said filtering paths for a lowest of said sub-bands has a low pass filtering response, a second of said filtering paths for a highest of said sub-bands has a high pass filtering response, and at least one other of said filtering paths has a bandpass filtering response.

10. A front end as claimed in claim 1, in which said signal path comprises a buffer stage.

11. A front end as claimed in claim 10, in which said buffer stage comprises a low noise amplifier.

12. A front end as claimed in claim 10, in which said signal path comprises an automatic gain control arrangement between said buffer stage and said filtering paths.

13. A front end as claimed in claim 1, further comprising a respective automatic gain control arrangement in each of said filtering paths.

14. A front end as claimed in claim 1, in which said signal path comprises a signal splitter having outputs for driving said filtering paths.

15. A front end as claimed in claim 14, in which said selecting arrangement is arranged to enable any one of said signal splitter outputs at a time.

16. A front end as claimed in claim 1, comprising a single monolithic integrated circuit.

17. A tuner comprising:

a radio frequency tuner front end including;

an input for receiving an input signal in an input band containing a plurality of channels;

a plurality of filtering paths arranged to receive said input signal and having fixed frequency responses for dividing said input band into a plurality of sub-bands, each of which contains a plurality of said channels;

a signal path between said input and said filtering paths having a bandwidth sufficiently wide to pass said input band and a substantially constant voltage standing wave ratio over said bandwidth; and

a selecting arrangement for enabling any one of said filtering paths at a time to supply a filtered signal; and

a first frequency changer.

18. A tuner as claimed in claim 17, in which said selecting arrangement comprises individually enablable input stages of said first frequency changer having inputs connected to outputs of said filtering paths.

19. A tuner as claimed in claim 17, comprising a first intermediate frequency filter connected to an output of said first frequency changer.

20. A tuner as claimed in claim 17, in which said first frequency changer is an upconverter.

21. A tuner as claimed in claim 17, comprising a second frequency changer.

22. A tuner as claimed in claim 21, in which said second frequency changer is a downconverter.

23. A tuner as claimed in claim 21, comprising a second intermediate frequency filter connected to an output of said second frequency changer.

24. A tuner as claimed in claim 17, comprising a single monolithic integrated circuit.

25. A tuner as claimed in claim 17, comprising a cable tuner.