Low intermediate frequency receiver and the same method thereof
View Patent ↗The present invention provides a low intermediate frequency receiver for receiving radio frequency signal and provides the sampling method thereof. The low intermediate frequency receiver firstly samples the radio frequency signal so as to convert it into digital signal of non-zero frequency domain. Secondly it compensates the digital signal of non-zero frequency domain to filter out the interfering signal therein. Finally, the compensated digital signal is frequency-shifted to the zero frequency domain. By using the low intermediate frequency receiver and the sampling method thereof according to the present invention, the interference at the zero frequency, like DC drift and intermodulation component, could be easily filtered out without imposing any great influence on the useful signals.
1. A method for sampling a received radio frequency signal, the method comprising:
sampling the radio frequency signal for converting the radio frequency signal into a digital signal of non-zero frequency domain;
compensating the digital signal of non-zero frequency domain for filtering out interfering signals therein; and
shifting the frequency of the compensated digital signal to a zero frequency domain,
wherein compensating the digital signal of non-zero frequency domain for filtering out interfering signals therein comprises compensating the digital signal of non-zero frequency domain through high-pass filtering, so as to filter out interfering signals at the zero frequency domain.
2. The method according to claim 1 , further comprising, performing low-pass filtering on the compensated digital signal, and providing the resulting signal to be processed.
3. The method according to claim 1 , further comprising, performing I/Q separation on the compensated digital signal.
4. A low intermediate frequency receiver for receiving radio frequency signal, the receiver comprising:
an analog to digital converting unit configured to sample a radio frequency signal to convert the radio frequency signal into a digital signal of non-zero frequency domain;
a compensation module configured to compensate the digital signal of non-zero frequency domain to filter out interfering signals therein; and
a mixing module configured to shift the compensated digital signal to the zero frequency domain,
wherein the compensation module comprises two high-pass filters.
5. The low intermediate frequency receiver according to claim 4 , further comprising a signal separator configured to perform I/Q separation on the compensated digital signal.
6. The low intermediate frequency receiver according to claim 5 , further comprising filter configured to filter the signal output from the compensation module and configured to output the filtered digital signal to the signal separator.
7. A mobile terminal used in radio communication system, the mobile terminal comprising:
a receiver, comprising:
a receiving unit configured to receive a radio frequency signal;
an analog to digital converting unit configured to sample the radio frequency signal so as to convert the radio frequency signal into a digital signal of non-zero frequency domain;
a compensation module configured to compensate the digital signal of non-zero frequency domain to filter out interfering signals therein; and
a mixing module configured to shift the compensated digital signal to the zero frequency domain; and
a signal processing means for performing unit configured to perform subsequent processing on the signal output from the mixing module,
wherein the compensation module comprises two high-pass filters.
8. The mobile terminal according to claim 7 , further comprising a signal separator configured to perform I/Q separation on the compensated digital signal.
9. The mobile terminal according to claim 8 , further comprising a filter configured to filter the signal output from the compensating module and configured to output the filtered digital signal to the signal separator.
10. A method for sampling a received radio frequency signal, the method comprising:
sampling the radio frequency signal for converting the radio frequency signal into a digital signal of non-zero frequency domain;
compensating the digital signal of non-zero frequency domain for filtering out interfering signals therein; and
shifting the frequency of the compensated digital signal to a zero frequency domain,
wherein sampling the radio frequency signal for converting the radio frequency signal into a digital signal of non-zero frequency domain comprises converting the radio frequency signal into two paths of digital signals of non-zero frequency domain under control of two sampling clock signals respectively.
11. The method according to claim 10 , wherein the frequencies f s of the two sampling clock signals equal (f c +f IF )/N and (f c −f IF )/N respectively, wherein N is a natural number, f c is the frequency of the radio frequency signal, f IF is an intermediate frequency value and 0≦f IF <f s .
12. The method according to claim 11 , wherein there is a relative time delay τ between the two sampling clock signals, τ satisfies the formula φ 2 −φ 1 =Nf s τ≠nπ, and wherein φ1 and φ2 are the initial phases of the radio frequency signals with respect to the two sampling clock signals respectively, and n is a natural number.
13. The method according to claim 12 , wherein the relative time delay τ satisfies the formula
Nf
s
τ
=
(
n
+
1
2
)
π
.
14. A low intermediate frequency receiver for receiving radio frequency signal, the receiver comprising:
an analog to digital converting unit configured to sample a radio frequency signal to convert the radio frequency signal into a digital signal of non-zero frequency domain;
a compensation module configured to compensate the digital signal of non-zero frequency domain to filter out interfering signals therein; and
a mixing module configured to shift the compensated digital signal to the zero frequency domain,
wherein the analog to digital converting unit comprises a first analog to digital converter and a second analog to digital converter, the first analog to digital converter and second analog to digital converter are respectively used for converting the radio frequency signal into two paths of digital signals of non-zero frequency domain under control of two sampling clock signals.
15. The low intermediate frequency receiver according to claim 14 , wherein the frequencies f s of the two sampling clock signals equal (f c +f IF )/N and (f c −f IF )/N respectively, wherein N is a natural number, f c is the frequency of the radio frequency signal, f IF is an intermediate frequency value and 0≦f IF <f s .
16. The low intermediate frequency receiver according to claim 15 , wherein there is a relative time delay τ between the two sampling clock signals, τ satisfies the formula φ 2 −φ 1 =Nf s τ≠nπ, and wherein φ1 and φ2 are the initial phases of the radio frequency signals with respect to the two sampling clock signals respectively, and n is a natural number.
17. The low intermediate frequency receiver according to claim 16 , wherein the relative time delay τ satisfies the formula
Nf
s
τ
=
(
n
+
1
2
)
π
.
18. A mobile terminal used in radio communication system, the mobile terminal comprising:
a receiver, comprising:
a receiving unit configured to receive a radio frequency signal;
an analog to digital converting unit configured to sample the radio frequency signal so as to convert the radio frequency signal into a digital signal of non-zero frequency domain;
a compensation module configured to compensate the digital signal of non-zero frequency domain to filter out interfering signals therein; and
a mixing module configured to shift the compensated digital signal to the zero frequency domain; and
a signal processing means for performing unit configured to perform subsequent processing on the signal output from the mixing module,
wherein the analog to digital converting unit comprises a first analog to digital converter and a second analog to digital converter, the first analog to digital converter and second analog to digital converter are respectively used for converting the radio frequency signal into two paths of digital signals of non-zero frequency domain under control of two sampling clock signals.
19. The mobile terminal according to claim 18 , wherein the frequencies f s of the two sampling clock signals are (f c +f IF )/N and (f c −f IF )/N respectively, wherein N is a natural number, f c is the frequency of the radio frequency signal, f IF is an intermediate frequency value and 0≦f IF <f s .
20. The mobile terminal according to claim 19 , wherein there is a relative time delay ti between the two sampling clock signals, τ satisfies the formula φ 2 −φ 1 =Nf s τ≠nπ, and wherein φ1 and φ2 are the initial phases of the radio frequency signals with respect to the two sampling clock signals respectively, and n is a natural number.