Linearisation and modulation device

• US 6,647,073 B2
• Filed: 11/01/2001
• Issued: 11/11/2003
• Est. Priority Date: 05/25/1999
• Status: Expired due to Term

• Current Assignee: Nokia Networks (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Tapio, Olli
• Primary Examiner(s): Le, Amanda T.
• Application Number:
  US09/999,569
• Publication Number:
  US 20020105378A1
• Time in Patent Office: 740 Days
• Field of Search: 375/296, 375/297, 375/284, 375/285, 375/302, 455/126, 330/75, 330/149, 330/151
• US Class Current: 375/297
• CPC Class Codes: H03C 3/40 using two signal paths the outputs of which have a predetermined phase difference and at least one output being amplitude-modulated
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3288 to compensate phase shift as a function of the amplitude
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

The present invention discloses a linearisation and modulation device for a power amplifier. The linearisation and modulation device comprises a digital vector modulator (103, 104, 105) for generating a modulated digital signal (IF_MOD) on the basis of digital baseband signals (IIN, QIN) and digital carrier signals (PH_S, PH_C); a correction value generating means (114, 108; 114a 108a) for generating an amplitude correction value (CV_AMAM) and a phase correction value (CV_AMPM) on the basis of said digital baseband signals (IIN, QIN) and on the basis of a non-linearity distortion generated in said power amplifier (6) arranged in a subsequent stage; an amplitude correction means (106) for generating a corrected digital signal (IF_OUT) on the basis of said modulated digital signal (IF_MOD) and said amplitude correction value (CV_AMAM); a phase correction means (111) for generating a corrected phase control signal on the basis of said phase correction value and an output signal of a phase control signal generation means (110); and a carrier signal generating means (112) for generating said carrier signals (PH_S, PH_C) on the basis of an output of said phase correction means (111). With such a device, a combined modulator and lineariser can be constructed, which leads to a compact system.

Claims

1. A linearisation and modulation device in a power amplifier, comprising

a digital vector modulator for generating a modulated digital signal (IF_MOD) on the basis of digital baseband signals (IIN, QIN) and digital carrier signals (PH_S, PH_C);

a correction value generating means for generating an amplitude correction value (CV_AMAM) and a phase correction value (CV_AMPM) on the basis of said digital baseband signals (IN, QIN) and on the basis of a non-linearity distortion generated in said power amplifier arranged in a subsequent stage;

an amplitude correction means for generating a corrected digital signal (IF_OUT) on the basis of said modulated digital signal (IF_MOD) and said amplitude correction value (CV_AMAM);

a phase correction means for generating a corrected phase control signal on the basis of said phase correction value and an output signal of a phase control signal generation means; and

a carrier signal generating means for generating said carrier signals (PH_S, PH_C) on the basis of an output of said phase correction means.

2. A linearisation and modulation device according to claim 1, wherein said digital vector modulator comprises

a first multiplying means for multiplying a first one of said digital baseband signals (IIN_BB) by a first one of said digital carrier signals (PH_S);

a second multiplying means for multiplying a second one of said digital baseband signals (QIN_BB) by a second one of said digital carrier signals (PH_C); and

an adding means for adding output signals of said first multiplying means and said second multiplying means.

3. A linearisation and modulation device according to claim 1, wherein said correction value generating means comprises a look-up-table and said amplitude and phase correction values (CV_AMAM, CV_AMPM) are read out on the basis of said digital baseband signals (IIN_BB, QIN_BB).

4. A linearisation and modulation device according to claim 3, wherein said amplitude and phase correction values (CV_AMAM, CV_AMPM) are read out on the basis of said digital baseband signals (IIN_BB, QIN_BB) and also on the basis of a transmitting frequency (TX_FREQ).

5. A linearisation and modulation device according to claim 3, wherein said look-up-table is adapted such that it can be updated by with a new correction value (CV_FB).

6. A linearisation and modulation device according to claim 5, wherein said correction value (CV_FB) is supplied from an adaptation device which receives as inputs said digital baseband signals (IIN_BB, QIN_BB) and a digital feedback signal (IF_FB) which corresponds to said corrected digital signal (IF_OUT).

7. A linearisation and modulation device according to claim 6, comprising

a signal converting means for generating an analogue signal (RF_CON) on the basis of said corrected digital signal (IF_OUT);

a power amplifier for amplifying said analogue carrier signal (RF_CON) and outputting an amplified carrier signal (RF_OUT); and

a signal de-converting means for generating said digital feedback signal (IF_FB) on the basis of said amplified carrier signal (RF_OUT).

8. A linearisation and modulation device according to claim 6, wherein said correction value generating means and said adaptation means are constructed as one unit which calculates said phase correction value (CV_AMPM) and said amplitude correction value (CV_AMAM) directly on the basis of said baseband signals (IIN, QIN) and said feedback correction value (IF_FB).

9. A linearisation and modulation device according to claim 1, wherein said amplitude correction means comprises a multiplier which multiplies said modulated digital signal (IF_MOD) by said amplitude correction value (CV_AMAM).

10. A linearisation and modulation device according to claim 1, wherein said phase correction means comprises an adder which adds said phase correction value and said output signal of said phase control signal generation means.

11. A linearisation and modulation device according to claim 1, wherein said digital baseband signals comprise a digital in-phase signal (IIN_BB) and a digital quadrature-phase signal (QIN_BB).

12. A linearisation and modulation device according to claim 1, wherein said modulated digital signal (IF_MOD) is a modulated digital intermediate frequency signal.

13. A linearisation and modulation device according to claim 1, wherein said corrected digital signal (IF_OUT) is a corrected digital intermediate frequency signal.