Transmission device with adaptive digital predistortion, transceiver with transmission device, and method for operating a transmission device

• US 20050105642A1
• Filed: 09/30/2004
• Published: 05/19/2005
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ceylan, Nazim, Muller, Jan-Erik
• Granted Patent: US 7,372,918 B2
• Time in Patent Office: Days
• US Class Current: 375/296
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3294 Acting on the real and imaginary components of the input signal
• CPC Class Codes: H03F 2200/105 A non-specified detector of the power of a signal being used in an amplifying circuit
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 2001/0425 with linearisation using predistortion
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

The invention provides a transmission device having adaptive digital predistortion, which has a transmission path and a feedback path. The transmission path contains a predistortion unit which takes a derived control signal (LS) and baseband signals applied to the input side as a basis for calculating the address of a predistortion coefficient (KOEFF1) stored in a memory and logically combines this predistortion coefficient with the applied baseband signals in a complex multiplication unit. The use of complex coefficients and of the complex multipliers allows compensation both for AM/AM distortion and for AM/PM distortion in an amplifier device connected downstream of the predistortion unit. Usefully, the feedback path of the transmission device with digital adaptive predistortion can also be implemented using the reception device in a transceiver.

Claims

1. A transmission device with adaptive digital predistortion, comprising:

a processor unit for providing a first discrete-value component (I) of a baseband signal (DAT1) at a first output and a second discrete-value component (Q) at a second output;

a predistortion unit, connected to the outputs of the processor unit, having a first and a second input and having a first and a second output,

wherein the predistortion unit comprises a coefficient unit for ascertaining a predistortion coefficient (KOEFF1), representing a complex value, on the basis of a first control signal (CONT1) at a first control input on the coefficient unit, a level for the first component (I), which is applied to the first input, and a level for the second component (Q), which is applied to the second input,

wherein the predistortion unit comprises a multiplication unit for outputting an output signal (DAT2), derived from the first component (I), and from the second component (Q), and from the predistortion coefficient (KOEFF1), having a first discrete value component (I2) at the first output and having a second discrete value component (Q2) at the second output,

wherein the predistortion unit comprises an adaptation unit for generating, and for transmitting to the coefficient unit, a new complex predistortion coefficient (KOEFF2) from at least one of the first component (I), the second component (Q), the first control signal (CONT1) and a second baseband signal (DAT3) which is applied to a second control input and comprises a first component (I3) and a second component (Q3);

a modulation device having a first input, which is operatively coupled to the first output of the predistortion unit, having a second input, which is operatively coupled to the second output of the predistortion unit, having a local oscillator input and having an output for providing signals applied to the input side and converted into an output signal using a local oscillator signal;

at least one amplification device having an input which is operatively coupled to the output of the modulation device;

an output unit, connected to the output of the at least one amplification device, for outputting a portion of an output signal from the at least one amplifier arrangement;

a conversion unit for converting the portion of the output signal into a baseband signal (DAT3) comprising a first and a second discrete value component (I3, Q3), having an input, which is connected to the output unit, and a first output for providing the first discrete value component (I3) and a second output for providing the second discrete value component (Q3), which are respectively coupled to one of at least two connections on the second control input of the predistortion unit;

wherein the predistortion unit has a first and a second operating state, and in the first operating state is configured to output signals (I) applied to the first input at the first output and signals (Q) applied to the second input at the second output, and in the second operating state is configured to output the first and second components (I2, Q2) of the derived output signal (DAT2) at the first and second outputs,

wherein the predistortion unit can be switched to the first or to the second operating state by the first control signal (CONT1) at the control input, and

a power control unit having an input for supplying a discrete-value power control signal (LS) to provide the first control signal (CONT1) at a first output, which is operatively coupled to the control input of the predistortion unit.

2. The transmission device of claim 1, wherein the coupling between the modulation unit and the amplification device comprises a regulatable amplification device having a control input which is operatively coupled to a second output on the power control unit to provide a second control signal (CONT2).

3. The transmission device of claim 2, wherein the first control signal (CONT1) at the first output and the second control signal (CONT2) at the second output of the power control unit are in the form of an identical control signal.

4. The transmission device of claim 1, wherein the coefficient unit for ascertaining the predistortion coefficients (KOEFF1) of the predistortion unit comprises a memory apparatus containing stored predistortion coefficients (KOEFF1) and also an address calculation unit, the address calculation unit configured to generate an address signal (ADR) for a predistortion coefficient stored in the memory apparatus from the level of the first and second discrete-value components (I, Q) and from the control signal (CONT1) at the first control input, and the memory apparatus configured to provide the complex predistortion coefficient (KOEFF1) determined by the address signal (ADR) to the multiplication unit.

5. The transmission device of claim 4, wherein the memory apparatus is configured to store a new predistortion coefficient (KOEFF2) which has been generated and has been transmitted from the adaptation unit to the coefficient unit in place of a predistortion coefficient (KOEFF1) determined by the address signal (ADR).

6. The transmission device of claim 1, wherein the adaptation unit is configured to generate a new complex predistortion coefficient on the basis of at least one of the predistortion coefficient (KOEFF1) and the predistorted baseband signal (DAT3).

7. The transmission device of claim 1, wherein the output unit is operatively coupled to an antenna (ANT) and is configured to detect an impedance change in the antenna (ANT).

8. The transmission device of claim 1, wherein the output unit comprises at least one directional coupler and is configured to detect a signal power which is present at the output of the at least one amplifier arrangement.

9. The transmission device of claim 1, wherein the output unit is configured to detect at least one of an amplitude and phase for an output signal and an amplitude and phase for a signal reflected by a circuit located downstream of the at least one amplifier arrangement.

10. The transmission device of claim 1, wherein the predistortion unit has a filter with adjustable filter bandwidth located downstream of it, the filter comprising an actuating input which is operatively coupled to the processor unit.

11. The transmission device of claim 1, further comprising:

a reception device which has an input and an output and which is configured to convert a signal applied to the input into a baseband signal (DAT3) comprising two discrete valve components, wherein the reception device comprises the conversion unit, and the output of the reception device is operatively coupled to the second control input of the predistortion unit.

12. The transmission device of claim 11, wherein the input of the reception device is connected to a switching apparatus which comprises at least two switching states, the input being operatively coupled to the output unit in a first switching state of the switching apparatus and being operatively coupled to a reception antenna (ANT) on a transceiver in a second switching state.

13. A method for regulating predistortion of a discrete value signal (DAT1) in a transmission device, comprising:

multiplying first and second components (I, Q) of the signal (DAT1) by a complex predistortion coefficient (KOEFF1) when a level for an output signal from a regulatable amplification device is exceeded as determined by a control signal (CONT1), where the coefficient (KOEFF1) is dependent on respective levels of the first and second components (I, Q) of the signal (DAT1) and on a control signal (CONT1).