SEMICONDUCTOR INTEGRATED CIRCUIT AND CIRCUIT OPERATION METHOD
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.
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.