Arrangement and method for radio communication

• US 6,370,360 B1
• Filed: 09/09/1998
• Issued: 04/09/2002
• Est. Priority Date: 09/11/1997
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Künkel, Lars Peter
• Primary Examiner(s): Kincaid, Lester G.
• Application Number:
  US09/150,163
• Time in Patent Office: 1,308 Days
• Field of Search: 455/76, 455/77, 455/75, 455/84, 455/86, 455/87, 455/85, 455/165.1, 455/183.1, 455/255, 455/256, 455/314, 455/318, 455/257-260, 455/74, 455/552, 455/553, 331/25
• US Class Current: 455/76
• CPC Class Codes: H03L 7/197 a time difference being used for locking the loop, the counter counting between numbers which are variable in time or the frequency divider dividing by a factor variable in time, e.g. for obtaining fractional frequency division H03L7/1806 takes precedence
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/0057 using diplexing or multiplexing filters for selecting the desired band
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

The present invention relates to a radio communication unit (20) comprising radio communication means (23, 25, 27) for communication (reception and/or transmission) in one or more frequency ranges with associated channel spacings. The radio communication means use oscillator signals for channel selection in the frequency ranges. The radio communication unit further comprises a system clock (77) generating a clock signal having a predetermined frequency that is not divisible by all the channel spacings. According to the invention the oscillator signals used in the channel selection are generated by a frequency synthesizer circuit (29) in the form of a fractional-N PLL circuit, said clock signal being fed as a reference frequency signal to the fractional-N PLL circuit. The invention also comprises a radio telephone comprising such a radio communication unit and the use of such a radio communication unit.

Claims

1. A radio communication unit comprising:

at least one antenna;

radio communication means connected to the antenna and arranged for communication in at least one frequency range having at least one associated channel spacing, said radio communication means in turn comprising channel selection means, said channel selection means being arranged to use oscillator signals of predetermined frequencies in the channel selection;

at least one system clock arranged to generate at least one clock signal having a predetermined clock frequency for timing the radio communication unit, wherein the clock frequency is not divisible by all the channel spacings; and

a frequency synthesizing circuit in the form of a fractional-N PLL circuit connected to the radio communication means and having at least one controllable oscillator for generating said oscillator signals, said fractional-N PLL circuit being further provided with a component which is connected to the system clock and is disposed to receive said clock signal of said predetermined clock frequency as a reference frequency signal.

2. The radio communication unit according to claim 1, wherein:

said component is disposed to receive a selected control signal, and to divide said predetermined frequency of said received clock signal in accordance with said control signal.

3. The radio communication unit according to claim 2, wherein the radio communication means comprises at least one receiver chain connected to the antenna and arranged for the reception of radio signals in at least one of the frequency ranges, and wherein the at least one chain includes a superheterodyne receiver chain comprising a first mixer and a first intermediate frequency stage connected to the first mixer, said first mixer being connected to the frequency synthesizing circuit and arranged to receive a predetermined number of the oscillator signals for use in channel selection.

4. The radio communication unit according to claim 1, wherein the radio communication means comprises at least one transmitter chain connected to the antenna and arranged for the transmission of radio signals in at least one of the frequency ranges.

5. The radio communication unit according to claim 4, wherein the at least one transmitter chain comprises:

a transmit intermediate frequency modulator, arranged to generate a modulated transmit intermediate frequency signal; and

a mixer connected to the transmit intermediate frequency modulator and arranged to mix up the transmit intermediate frequency signal to channels in at least one of the frequency ranges, the mixer being connected to the frequency synthesizer circuit and arranged to receive a predetermined number of the oscillator signals for use in the mixing.

6. The radio communication unit according to claim 5, wherein the transmit intermediate frequency modulator is connected to the system clock and arranged to receive the clock signal for use in the generation of the transmit intermediate frequency signal.

7. A radio telephone arranged for communication in at least one mobile telephony system, the radio telephone comprising a radio communication unit having:

at least one antenna;

radio communication means connected to the antenna and arranged for communication in at least one frequency range having at least one associated channel spacing, said radio communication means in turn comprising channel selection means, said channel selection means being arranged to use oscillator signals of predetermined frequencies in the channel selection;

at least one system clock arranged to generate at least one clock signal having a predetermined clock frequency for the timing of the radio communication unit, wherein the clock frequency is not divisible by all the channel spacings; and

a frequency synthesizing circuit in the form of a fractional-N PLL circuit connected to the radio communication means and having at least one controllable oscillator for generating said oscillator signals, said fractional-N PLL circuit being further provided with a component connected to the system clock and disposed to receive said clock signal of said predetermined clock frequency as a reference frequency signal.

8. The radio telephone according to claim 7, wherein the radio communication unit is arranged for use in at least AMPS and PCS1900.

9. A method for communicating in a specified number of frequency ranges, each having an associated channel spacing and a plurality of channels, the method comprising the steps of:

generating a clock signal of a predetermined frequency that is not divisible by all of the channel spacings;

coupling said clock signal to a frequency synthesizer circuit having a controllable oscillator corresponding to each of said frequency ranges;

operating said frequency synthesizer circuit to generate an oscillator signal corresponding to the channel spacing associated with a given one of said frequency ranges, and having a frequency equal to said predetermined frequency of said clock signal multiplied by a factor equal to (N+F/Q)/R, wherein N, F, Q and R respectively comprise freely selectable integers, except that the quantity (N+F/Q) comprises a rational number, and the quantity (QR) is equal to said clock signal frequency divided by a specified function of said clock signal frequency and the channel spacing of said given frequency range; and

using said oscillator signal to select one of the plurality of channels of said given frequency range.

10. The method according to claim 9, wherein the step of generating an oscillator signal using the frequency synthesizer circuit further comprises using a fractional-N PLL circuit that is arranged to utilize the clock signal as a reference frequency signal.

11. The method according to claim 10, wherein said step of generating said oscillator signal further comprises using the fractional-N PLL circuit to control the controllable oscillator corresponding to said given frequency range.

12. The method according to claim 9, further comprising transmitting data over the selected channel.

13. The method according to claim 12, wherein the step of transmitting data further includes transmitting radio telephone data arranged for communication in at least AMPS and PCS1900.

14. The method according to claim 12, wherein the step of transmitting data further includes transmitting radio communication data in a mobile telephony system.

15. The method according to claim 12, wherein the step of transmitting data further includes transmitting radio communication data in a satellite communication system.

16. A radio communication unit comprising:

at least one antenna;

radio communication means connected to the antenna and arranged for communication in a plurality of frequency ranges, each having an associated channel spacing and a plurality of channels, said radio communication means comprising channel selection means arranged to use a plurality of oscillator signals of predetermined frequencies in the channel selection;

a system clock arranged to generate a clock signal having a predetermined clock frequency for timing the radio communication unit, wherein the clock frequency is not divisible by all the channel spacings;

a fractional-N PLL circuit connected to the radio communication means and disposed to provide a PLL circuit output signal, said PLL circuit comprising a main frequency divider, a reference frequency divider coupled to receive said clock signal of said predetermined frequency, and at least one controllable oscillator; and

said main and reference frequency dividers are responsive to respective control signals to divide said clock signal frequency, and to cooperatively adjust said PLL circuit output signal to the predetermined frequency of any selected one of said oscillator signals.

17. The radio communication unit of claim 16, wherein:

said PLL circuit is disposed to generate a given oscillator signal corresponding to the channel spacing associated with a given one of said frequency ranges, said given oscillator signal having a frequency equal to said predetermined frequency of said clock signal multiplied by a factor equal to (N+F/Q)R, wherein N, F, Q and R respectively comprise freely selectable integers, except that the quantity (N+F/Q) comprises a rational number, and the quantity (QR) is equal to said clock signal frequency divided by a specified function of said clock signal frequency and the channel spacing of said given frequency range; and

N, F and Q are associated with said main frequency divider and R is associated with said reference frequency divider.

18. The radio communication unit of claim 16 wherein:

said fractional-N PLL circuit comprises a plurality of controllable oscillators.

19. The radio communication unit of claim 16 wherein:

said radio communication means comprises at least one receiver chain connected to the antenna and arranged for the reception of radio signals in at least one of the frequency ranges, and wherein the at least one chain includes a superheterodyne receiver chain comprising a first mixer and a first intermediate frequency stage connected to the first mixer, said first mixer being connected to the fractional-N PLL circuit and arranged to receive a predetermined number of the oscillator signals for use in channel selection.

20. The radio communication unit of claim 16 wherein:

said radio communication means comprises at least one transmitter chain connected to said antenna and arranged for the transmission of radio signals in at least one of the frequency ranges.

21. The radio communication unit of claim 20 wherein said at least one transmitter chain comprises:

a transmit intermediate frequency modulator, arranged to generate a modulated transmit intermediate frequency signal; and

a mixer connected to the transmit intermediate frequency modulator and arranged to mix up the transmit intermediate frequency signal to channels in at least one of the frequency ranges, the mixer being connected to the fractional-N PLL circuit and arranged to receive a predetermined number of the oscillator signals for use in the mixing.

22. The radio communication unit of claim 21 wherein:

said transmit intermediate frequency modulator is connected to said system clock and arranged to receive said clock signal for use in the generation of said intermediate frequency signal.

23. The radio communication unit of claim 16 wherein:

said radio communication unit is incorporated into a radio telephone unit arranged for use in at least AMPS and PCS1900.