SEMICONDUCTOR INTEGRATED CIRCUIT AND CIRCUIT OPERATION METHOD

• US 20100056201A1
• Filed: 08/19/2009
• Published: 03/04/2010
• Est. Priority Date: 08/29/2008
• Status: Abandoned Application

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Okada, Yuki, Hikasa, Kazuhiko, Yamamoto, Satoru, AKAMINE, Yukinori
• Application Number:
  US12/543,504
• Publication Number:
  US 20100056201A1
• Time in Patent Office: Days
• US Class Current: 455/552.100
• CPC Class Codes: H04B 1/0017 Digital filtering H04B1/001 takes precedence; digital filters per se H03H17/00

Abstract

There is a need for reducing a chip footprint of a multimode-compatible semiconductor integrated circuit. A reception-based analog front-end unit converts a first RF reception signal according to a first communication system and a second RF reception signal according to a second communication system into a first reception-based analog base band signal having a large signal band and a second reception-based analog base band signal having a small signal band, respectively. An oversampling analog-to-digital converter generates first and second reception-based digital base band signals. A first digital filter is used for a decimation process on the first and second reception-based digital base band signals in common with each other. Second digital filters perform a down-sampling process to generate the first reception-based digital base band signal having the large first sampling rate. Third digital filters perform a down-sampling process to generate the second reception-based digital base band signal having the small second sampling rate.

Claims

1. A semiconductor integrated circuit comprising:

a reception-based analog front-end unit;

a reception-based digital front-end unit; and

a digital interface unit,

wherein the reception-based analog front-end unit functions as a receiver for down-converting an RF reception signal into a reception-based analog base band signal, the RF reception signal being received at an antenna mounted on a communication terminal,

wherein the reception-based digital front-end unit comprises an analog-to-digital converter and a reception-based digital filter unit,

wherein the analog-to-digital converter converts the reception-based analog base band signal supplied from an output of the reception-based analog front-end unit into a reception-based digital base band signal,

wherein the reception-based digital base band signal from the analog-to-digital converter is transmitted to the digital interface unit via the reception-based digital filter unit,

wherein the digital interface unit is capable of supplying an external digital base band processing unit with the reception-based digital base band signal transmitted from the reception-based digital filter unit,

wherein the reception-based analog front-end unit is capable of down-converting a first RF reception signal according to a first communication system and a second RF reception signal according to a second communication system received at the antenna into a first reception-based analog base band signal having a first signal band and a second reception-based analog base band signal having a second signal band narrower than the first signal band, respectively,

wherein the analog-to-digital converter of the reception-based digital front-end unit comprises an oversampling analog-to-digital converter,

wherein the oversampling analog-to-digital converter is capable of converting the first reception-based analog base band signal and the second reception-based analog base band signal supplied from the reception-based analog front-end unit into a first reception-based digital base band signal and a second reception-based digital base band signal, respectively,

wherein the reception-based digital filter unit of the reception-based digital front-end unit comprises a first digital filter coupled to an output of the oversampling analog-to-digital converter,

wherein the first digital filter is capable being used for a decimation process on the first reception-based digital base band signal supplied from the oversampling analog-to-digital converter and a decimation process on the second reception-based digital base band signal supplied from the oversampling analog-to-digital converter in common with each other,

wherein the reception-based digital filter unit further comprises a second digital filter and a third digital filter parallel coupled between an output of the first digital filter and the digital interface unit,

wherein the second digital filter down-samples the first reception-based digital base band signal, based on the first communication system, from the output of the first digital filter and thereby supplies the digital interface unit with the first reception-based digital base band signal having a first sampling rate, and

wherein the third digital filter down-samples the second reception-based digital base band signal, based on the second communication system, from the output of the first digital filter and thereby supplies the digital interface unit with the second reception-based digital base band signal having a second sampling rate smaller than the first sampling rate.

2. The semiconductor integrated circuit according to claim 1,

wherein the second digital filter generates the first reception-based digital base band signal having the first sampling rate,

wherein the third digital filter generates the second reception-based digital base band signal having the second sampling rate, and

wherein the second digital filter and the third digital filter are provided with a down-sampling rate conversion ratio difference equivalent to a difference between the first signal band for the first reception-based analog base band signal and the second signal band for the second reception-based analog base band signal.

3. The semiconductor integrated circuit according to claim 2,

wherein the second digital filter comprises an interpolation section having an interpolation ratio assigned a specified value, and

wherein the specified value of the interpolation ratio generates the down-sampling rate conversion ratio difference.

4. The semiconductor integrated circuit according to claim 1,

wherein the reception-based digital front-end unit further comprises a reception memory buffer that temporarily stores the reception-based digital base band signal processed by the reception-based digital filter unit and then supplies the signal to the digital interface unit.

5. The semiconductor integrated circuit according to claim 4,

wherein the second digital filter comprises a first root raised cosine filter for reducing an inter-decoding interference.

6. The semiconductor integrated circuit according to claim 5,

wherein the reception-based analog front-end unit and the reception-based digital front-end unit process the first RF reception signal according to a WCDMA communication system as the first communication system and the second RF reception signal according to a GSM/EDGE communication system as the second communication system.

7. The semiconductor integrated circuit according to claim 4, further comprising:

a transmission-based digital front-end unit; and

a transmission-based analog front-end unit,

wherein the digital interface unit is capable of supplying the transmission-based digital front-end unit with a transmission-based digital base band signal transmitted from an outside digital base band processing unit,

wherein the transmission-based digital front-end unit comprises a transmission-based digital filter unit and a D/A converter,

wherein the transmission-based digital filter unit transmits the transmission-based digital base band signal supplied from the digital interface unit to the D/A converter,

wherein the D/A converter converts the transmission-based digital base band signal supplied from an output of the transmission-based digital filter unit into a transmission-based analog base band signal, and

wherein the transmission-based analog front-end unit functions as a transmitter that up-converts the transmission-based analog base band signal from an output of the D/A converter into an RF transmission signal.

8. The semiconductor integrated circuit according to claim 7,

wherein the transmission-based digital filter unit comprises a fourth digital filter and a fifth digital filter parallel coupled between the digital interface unit and an input of the D/A converter,

wherein the fourth digital filter up-samples a first transmission-based digital base band signal, based on the first communication system, supplied from the digital interface unit and thereby supplies the input of the D/A converter with the first transmission-based digital base band signal having a third sampling rate, and

wherein the fifth digital filter up-samples a second transmission-based digital base band signal, based on the second communication system, supplied from the digital interface unit and thereby supplies the input of the D/A converter with the second transmission-based digital base band signal having a fourth sampling rate.

9. The semiconductor integrated circuit according to claim 7,

wherein the transmission-based digital front-end unit further comprises a transmission buffer memory that temporarily stores transmission-based digital base band signal transmitted from the outside digital base band processing unit and then supplies the signal to the transmission-based digital filter unit.

10. The semiconductor integrated circuit according to claim 9,

wherein the fourth digital filter comprises a second root raised cosine filter for reducing an inter-decoding interference.

11. An operation method of a semiconductor integrated circuit comprising a reception-based analog front-end unit, a reception-based digital front-end unit, and a digital interface unit,

wherein the reception-based analog front-end unit functions as a receiver for down-converting an RF reception signal into a reception-based analog base band signal, the RF reception signal being received at an antenna mounted on a communication terminal,

wherein the reception-based digital front-end unit comprises an analog-to-digital converter and a reception-based digital filter unit,

wherein the analog-to-digital converter converts the reception-based analog base band signal supplied from an output of the reception-based analog front-end unit into a reception-based digital base band signal,

wherein the reception-based digital base band signal from the analog-to-digital converter is transmitted to the digital interface unit via the reception-based digital filter unit,

wherein the digital interface unit is capable of supplying an external digital base band processing unit with the reception-based digital base band signal transmitted from the reception-based digital filter unit,

wherein the reception-based analog front-end unit is capable of down-converting a first RF reception signal according to a first communication system and a second RF reception signal according to a second communication system received at the antenna into a first reception-based analog base band signal having a first signal band and a second reception-based analog base band signal having a second signal band narrower than the first signal band, respectively,

wherein the analog-to-digital converter of the reception-based digital front-end unit comprises an oversampling analog-to-digital converter,

wherein the oversampling analog-to-digital converter is capable of converting the first reception-based analog base band signal and the second reception-based analog base band signal supplied from the reception-based analog front-end unit into a first reception-based digital base band signal and a second reception-based digital base band signal, respectively,

wherein the reception-based digital filter unit of the reception-based digital front-end unit comprises a first digital filter coupled to an output of the oversampling analog-to-digital converter,

wherein the first digital filter is capable of being used for a decimation process on the first reception-based digital base band signal supplied from the oversampling analog-to-digital converter and a decimation process on the second reception-based digital base band signal supplied from the oversampling analog-to-digital converter in common with each other,

wherein the reception-based digital filter unit further comprises a second digital filter and a third digital filter parallel coupled between an output of the first digital filter and the digital interface unit,

wherein the second digital filter down-samples the first reception-based digital base band signal, based on the first communication system, from the output of the first digital filter and thereby supplies the digital interface unit with the first reception-based digital base band signal having a first sampling rate, and

wherein the third digital filter down-samples the second reception-based digital base band signal, based on the second communication system, from the output of the first digital filter and thereby supplies the digital interface unit with the second reception-based digital base band signal having a second sampling rate smaller than the first sampling rate.

12. The operation method of the semiconductor integrated circuit according to claim 11,

wherein the second digital filter generates the first reception-based digital base band signal having the first sampling rate,

wherein the third digital filter generates the second reception-based digital base band signal having the second sampling rate, and

wherein the second digital filter and the third digital filter are provided with a down-sampling rate conversion ratio difference equivalent to a difference between the first signal band for the first reception-based analog base band signal and the second signal band for the second reception-based analog base band signal.

13. The operation method of the semiconductor integrated circuit according to claim 12,

wherein the second digital filter comprises an interpolation section having an interpolation ratio assigned a specified value, and

wherein the specified value of the interpolation ratio generates the down-sampling rate conversion ratio difference.

14. The operation method of the semiconductor integrated circuit according to claim 11,

wherein the reception-based digital front-end unit further comprises a reception memory buffer that temporarily stores the reception-based digital base band signal processed by the reception-based digital filter unit and then supplies the signal to the digital interface unit.

15. The operation method of the semiconductor integrated circuit according to claim 14,

wherein the second digital filter comprises a first root raised cosine filter for reducing an inter-decoding interference.

16. The operation method of the semiconductor integrated circuit according to claim 15,

wherein the reception-based analog front-end unit and the reception-based digital front-end unit process the first RF reception signal according to a WCDMA communication system as the first communication system and the second RF reception signal according to a GSM/EDGE communication system as the second communication system.

17. The operation method of the semiconductor integrated circuit according to claim 14,

wherein the semiconductor integrated circuit further comprises a transmission-based digital front-end unit and a transmission-based analog front-end unit,

wherein the digital interface unit is capable of supplying the transmission-based digital front-end unit with a transmission-based digital base band signal transmitted from an outside digital base band processing unit,

wherein the transmission-based digital front-end unit comprises a transmission-based digital filter unit and a D/A converter,

wherein the transmission-based digital filter unit transmits the transmission-based digital base band signal supplied from the digital interface unit to the D/A converter,

wherein the D/A converter converts the transmission-based digital base band signal supplied from an output of the transmission-based digital filter unit into a transmission-based analog base band signal, and

wherein the transmission-based analog front-end unit functions as a transmitter that up-converts the transmission-based analog base band signal from an output of the D/A converter into an RF transmission signal.

18. The operation method of the semiconductor integrated circuit according to claim 17,

wherein the transmission-based digital filter unit comprises a fourth digital filter and a fifth digital filter parallel coupled between the digital interface unit and an input of the D/A converter,

wherein the fourth digital filter up-samples a first transmission-based digital base band signal, based on the first communication system, supplied from the digital interface unit and thereby supplies the input of the D/A converter with the first transmission-based digital base band signal having a third sampling rate, and

wherein the fifth digital filter up-samples a second transmission-based digital base band signal, based on the second communication system, supplied from the digital interface unit and thereby supplies the input of the D/A converter with the second transmission-based digital base band signal having a fourth sampling rate.

19. The operation method of the semiconductor integrated circuit according to claim 17,

wherein the transmission-based digital front-end unit further comprises a transmission buffer memory that temporarily stores the transmission-based digital base band signal transmitted from the outside digital base band processing unit and then supplies the signal to the transmission-based digital filter unit.

20. The operation method of the semiconductor integrated circuit according to claim 19,

wherein the fourth digital filter comprises a second root raised cosine filter for reducing an inter-decoding interference.