A transmitter is disclosed. The transmitter has an RF portion having an amplifier for amplifying a signal for transmission. The RF portion is fed by a baseband portion. The baseband portion comprises: means for generating a pair of in-phase (I) and quadrature-phase (Q) data signals; and a limiter arrangement for preventing the amplitude of both the I and Q data signals exceeding a pretermined level.
1. A transmitter including a RF portion including an amplifier for amplifying a signal for transmission, the RF portion being fed by a baseband portion, wherein the baseband portion comprises:
means for generating a pair of in-phase (I) and quadrature-phase (Q) data signals;
a limiter arrangement which prevents an amplitude of the I and Q data signals from exceeding a predetermined level; and
means for providing phase rotation of the in-phase (I) and quadrature-phase (Q) data signals; and wherein
an output of the means for phase rotation is coupled to an input of the limiter arrangement.
2. A transmitter as claimed in claim 1 , wherein:
the limiter comprises a pair of limiters for limiting the I and Q data signals respectively.
3. A portable telephone comprising:
a transmitter as claimed in claim 2 .
4. A portable telephone as claimed in claim 3 , which operates according to the WCDMA communication standard.
5. A portable telephone as claimed in claim 4 which operates according to a FDD variant of WCDMA.
6. A portable telephone as claimed in claim 4 which operates according to a TDD variant of WCDMA.
7. A portable telephone as claimed in claim 4 which operates according to both FDD and TDD variants of the WCDMA communication standard.
8. A base station comprising:
a transmitter as claimed in claim 2 .
9. A base station as claimed in claim 8 which operates according to the WCDMA communication standard.
10. A base station as claimed in claim 9 which operates according to a FDD variant of WCDMA.
11. A base station as claimed in claim 9 which operates according to a TDD variant of WCDMA.
12. A base station as claimed in claim 9 which operates according to both FDD and TDD variants of the WCDMA communication standard.
13. A transmitter as claimed in claim 1 wherein the limiter arrangement comprises:
a converter for converting the I and Q data signals into a pair of signals representing magnitude data and phase data of the signal for transmission;
a limiter which limits the amplitude of the magnitude data signal from exceeding a predetermined level; and
a converter for converting the limited magnitude data signal and phase data signal into a pair of I and Q data signals.
14. A portable telephone comprising:
a transmitter as claimed in claim 13 .
15. A portable telephone as claimed in claim 14 , which operates according to the WCDMA communication standard.
16. A portable telephone as claimed in claim 15 which operates according to a FDD variant of WCDMA.
17. A portable telephone as claimed in claim 15 which operates according to a TDD variant of WCDMA.
18. A portable telephone as claimed in claim 15 which operates according to both FDD and TDD variants of the WCDMA communication standard.
19. A base station comprising:
a transmitter as claimed in claim 13 .
20. A base station as claimed in claim 19 which operates according to the WCDMA communication standard.
21. A base station as claimed in claim 20 which operates according to a FDD variant of WCDMA.
22. A base station as claimed in claim 20 which operates according to a TDD variant of WCDMA.
23. A base station as claimed in claim 20 which operates according to both FDD and TDD variants of the WCDMA communication standard.
24. A portable telephone comprising:
a transmitter as claimed in claim 1 .
25. A portable telephone as claimed in claim 24 , which operates according to the WCDMA communication standard.
26. A portable telephone as claimed in claim 25 which operates according to a FDD variant of WCDMA.
27. A portable telephone as claimed in claim 25 which operates according to a TDD variant of WCDMA.
28. A portable telephone as claimed in claim 25 which operates according to both FDD and TDD variants of the WCDMA communication standard.
29. A base station comprising:
a transmitter as claimed in claim 1 .
30. A base station as claimed in claim 29 which operates according to the WCDMA communication standard.
31. A base station as claimed in claim 30 which operates according to a FDD variant of WCDMA.
32. A base station as claimed in claim 30 which operates according to a TDD variant of WCDMA.
33. A base station as claimed in claim 30 which operates according to both FDD and TDD variants of the WCDMA communication standard.