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

• US 7,372,918 B2
• Filed: 09/30/2004
• Issued: 05/13/2008
• Est. Priority Date: 09/30/2003
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ceylan, Nazim, Muller, Jan-Erik
• Primary Examiner(s): Fan; Chieh M.
• Assistant Examiner(s): Ejaz; Naheed
• Application Number:
  US10/955,385
• Publication Number:
  US 20050105642A1
• Time in Patent Office: 1,321 Days
• Field of Search: 375/295, 375/296, 375/297, 375/302, 375/308, 375/309, 375/315, 330/127, 330/129, 330/136, 330/144, 330/147, 330/149
• 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 of a baseband signal at a first output and a second discrete-value component 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, representing a complex value, on the basis of a first control signal at a first control input on the coefficient unit, a level for the first component, which is applied to the first input, and a level for the second component, which is applied to the second input,

wherein the predistortion unit comprises a multiplication unit for outputting an output signal, derived from the first component, and from the second component, and from the predistortion coefficient, having a third discrete value component at the first output and having a fourth discrete value component 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 from at least one of the first component, the second component, the first control signal and a second baseband signal which is applied to a second control input and comprises a fifth component and a sixth component;

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;

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 the second baseband signal comprising the fifth and the sixth discrete values components, having an input, which is connected to the output unit, and a first output for providing the fifth discrete value component and a second output for providing the sixth discrete value component, 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 the first component at the first output and the second component at the second output, and in the second operating state is configured to output the third and fourth components of the derived output signal 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 at the control input, and

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

2. The transmission device of claim 1, whereinthe 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.

3. The transmission device of claim 2, wherein the first control signal at the first output and the second control signal 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 of the predistortion unit comprises a memory apparatus stores the predistortion coefficients and also an address calculation unit, the address calculation unit configured to generate an address signal for the predistortion coefficient stored in the memory apparatus from the level of the first and second discrete-value components and from the first control signal at the first control input, and the memory apparatus configured to provide the complex predistortion coefficient determined by the address signal to the multiplication unit.

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

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

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

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 the output signal of the at least one amplification device 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, 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 the second baseband signal comprising the fifth and the sixth discrete values 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 on a transceiver in a second switching state.