WIDEBAND RECEIVER FOR WIRELESS COMMUNICATION SYSTEM AND METHOD FOR CONTROLLING THE SAME

• US 20110081880A1
• Filed: 08/30/2010
• Published: 04/07/2011
• Est. Priority Date: 10/01/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: AHN, Cheol-Woo
• Granted Patent: US 8,467,757 B2
• Time in Patent Office: Days
• US Class Current: 455/319
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 2215/065 by changing the frequency of clock or reference frequency

Abstract

A wideband receiver for a wireless communication system and a method for controlling the same are provided. In the wideband receiver for a wireless communication system, a receive path includes a mixer for receiving a Radio Frequency (RF) signal having a frequency f_SG and for converting the RF signal into an Intermediate Frequency (IF) signal having a frequency f_IF by mixing the RF signal with a first local oscillation signal having a first local oscillation frequency f_LO1, and at least one Phase Locked Loop (PLL) for providing the local oscillation signal to the mixer. A control block determines whether a half-IF signal having a center frequency of f_SG-f_IF/2 exists in the IF signal, and when the half-IF signal exists, controls the at least one PLL to generate a second local oscillation signal having a second local oscillation frequency f_LO2 greater than the first local oscillation frequency f_LO1.

Claims

1. A wideband receiver for a wireless communication system, the wideband receiver comprising:

a receive path having a mixer for receiving a Radio Frequency (RF) signal having a frequency f_SG and for converting the RF signal into an Intermediate Frequency (IF) signal having a frequency f_IF by mixing the RF signal with a first local oscillation signal having a first local oscillation frequency f_LO1, and at least one Phase Locked Loop (PLL) for providing the first local oscillation signal to the mixer; and

a control block for determining whether a half-IF signal having a center frequency of f_SG-f_IF/2 exists in the IF signal, and when the half-IF signal exists, for controlling the at least one PLL to generate a second local oscillation signal having a second local oscillation frequency f_LO2 greater than the first local oscillation frequency f_LO1.

2. The wideband receiver of claim 1, wherein the control block is configured to reset configurations of an Analog-to-Digital Converter (ADC) and a Digital Down-Converter (DDC) in the receive path so that the ADC and the DDC process an IF signal changed by the second local oscillation frequency f_LO2.

3. The wideband receiver of claim 2, wherein the second local oscillation frequency is determined based on a sampling rate of the ADC.

4. The wideband receiver of claim 1, wherein the second local oscillation frequency is determined by adding the frequency f_SG of the RF signal to the frequency f_IF of the IF signal.

5. The wideband receiver of claim 1, wherein:

the control block is connected to a switch for selecting one of a first PLL generating a local oscillation signal having the first local oscillation frequency f_LO1 and a second PLL generating a local oscillation signal having a second local oscillation frequency f_LO2, and for connecting the selected PLL to the mixer, and

wherein the control block controls the switch to select the second PLL when a half-IF signal having a center frequency of f_SG-f_IF/2 exists in the IF signal.

6. The wideband receiver of claim 1, wherein the control block comprises:

a coupling block for detecting the IF signal, which is output from the mixer and is subject to IF filtering;

a Band Pass Filter (BPF) for filtering the IF signal using a pass band having a center frequency of f_SG-f_IF/2;

a detector for converting an output signal of the BPF into a voltage signal; and

a frequency decision block for determining that the half-IF signal exists when a level of the voltage signal exceeds a predetermined threshold.

7. A method for controlling a wideband receiver for a wireless communication system, the method comprising:

detecting an Intermediate Frequency (IF) signal from a receive path having a mixer for receiving a Radio Frequency (RF) signal having a frequency f_SG and converting the RF signal into the IF signal having a frequency f_IF by mixing the RF signal with a first local oscillation signal having a first local oscillation frequency f_LO1;

determining whether a half-IF signal having a center frequency of f_SG-f_IF/2 exists in the IF signal; and

when the half-IF signal exists, providing a second local oscillation signal to the receive path, the second local oscillation signal having a second local oscillation frequency f_LO2 greater than the first local oscillation frequency.

8. The method of claim 7, further comprising:

resetting configurations of an Analog-to-Digital Converter (ADC) and a Digital Down-Converter (DDC) in the receive path so that the ADC and the DDC process an IF signal changed by the second local oscillation frequency f_LO2.

9. The method of claim 8, wherein the second local oscillation frequency is determined based on a sampling rate of the ADC.

10. The method of claim 7, wherein the second local oscillation frequency is determined by adding the frequency f_SG of the RF signal to the frequency f_IF of the IF signal.

11. The method of claim 7, wherein the providing of the second local oscillation signal comprises:

selecting one of a first Phase Locked Loop (PLL) generating a local oscillation signal having the first local oscillation frequency f_LO1 and a second PLL generating a local oscillation signal having a second local oscillation frequency f_LO2; and

connecting the selected PLL to the mixer.

12. The method of claim 7, wherein the determining of whether the half-IF signal exists comprises:

filtering the IF signal via a pass band having a center frequency of f_SG-f_IF/2;

converting the filtered signal into a voltage signal; and

determining that the half-IF signal exists when a level of the voltage signal exceeds a predetermined threshold.

13. A wideband receiver for a wireless communication system, the wideband receiver comprising:

a main receive path having a first mixer for receiving a first Radio Frequency (RF) signal having a frequency f_SG, received via a first antenna, and for converting the first RF signal into a first Intermediate Frequency (IF) signal;

a diversity receive path having a second mixer for receiving a second RF signal having a frequency f_SG, received via a second antenna, and for converting the second RF signal into a second IF signal;

a first Phase Locked Loop (PLL) for generating a first local oscillation signal having a first local oscillation frequency and for providing the first local oscillation signal to the first mixer in the main receive path;

a second PLL for generating a second local oscillation signal having a second local oscillation frequency different from the first local oscillation frequency;

a switch for selecting one of the first PLL and the second PLL, and for connecting the selected PLL to the second mixer in the diversity receive path; and

a control block for controlling the switch to select the second PLL, for monitoring whether reception performance of the diversity receive path has been improved by the second local oscillation signal from the second PLL, and when the reception performance has been improved, for controlling the first PLL such that the first local oscillation signal is generated to have the second local oscillation frequency.

14. The wideband receiver of clam 13, wherein:

the control block controls the switch to select the second PLL when a difference between a Receive Signal Strength Indicator (RSSI) of a first received signal demodulated from the first IF signal generated in one of the main receive path and the diversity receive path using the first local oscillation frequency and a Carrier to Noise Ratio (C/N) for the first received signal exceeds a predetermined threshold, and

the control block controls the first PLL such that the first local oscillation signal is generated to have the second local oscillation frequency, when a difference between an RSSI of a second received signal demodulated from the second IF signal generated in the diversity receive path using the second local oscillation frequency and a C/N for the second received signal does not exceed the threshold.

15. The wideband receiver of clam 13, wherein the control block is configured to reset configurations of an Analog-to-Digital Converter (ADC) and a Digital Down-Converter (DDC) in the main receive path so that the ADC and the DDC process an IF signal changed by the second local oscillation frequency f_LO2.

16. The wideband receiver of claim 15, wherein the second local oscillation frequency is determined based on a sampling rate of the ADC.

17. A method for controlling a wideband receiver for a wireless communication system, the method comprising:

controlling both a main receive path and a diversity receive path to operate according to a first local oscillation signal having a first local oscillation frequency generated by a first Phase Locked Loop (PLL), the main receive path having a first mixer for receiving a first Radio Frequency (RF) signal having a frequency f_SG, received via a first antenna and for converting the first RF signal into a first Intermediate Frequency (IF) signal, the diversity receive path having a second mixer for receiving a second RF signal having a frequency f_SG, received via a second antenna and converting the second RF signal into a second IF signal;

controlling the diversity receive path to operate according to a second local oscillation signal having a second local oscillation frequency generated by a second PLL, and monitoring whether reception performance of the diversity receive path has been improved by the second local oscillation signal from the second PLL; and

when the reception performance has been improved, controlling the first PLL such that the first local oscillation signal is generated to have the second local oscillation frequency.

18. The method of claim 17, wherein the monitoring of the reception performance comprises controlling the second PLL to be connected to the second mixer in the diversity receive path when a difference between a Receive Signal Strength Indicator (RSSI) of a first received signal demodulated from the first IF signal generated in one of the main receive path and the diversity receive path using the first local oscillation frequency, and a Carrier to Noise Ratio (C/N) for the first received signal exceeds a predetermined threshold.

19. The method of claim 17, wherein the controlling of the first PLL comprises controlling the first PLL such that the first local oscillation signal is generated to have the second local oscillation frequency when a difference between an RSSI of a second received signal demodulated from the second IF signal generated in the diversity receive path using the second local oscillation frequency and a C/N for the second received signal does not exceed the threshold.

20. The method of claim 17, further comprising resetting configurations of an Analog-to-Digital Converter (ADC) and a Digital Down-Converter (DDC) in the main receive path so that the ADC and the DDC process an IF signal changed by the second local oscillation frequency f_LO2.

21. The method of claim 20, wherein the second local oscillation frequency is determined based on a sampling rate of the ADC.

22. A wideband receiver for a wireless communication system, the wideband receiver comprising:

a receive path for receiving a Radio Frequency (RF) signal and for generating a first local oscillation frequency based on the RF signal and an Intermediate Frequency signal; and

a control block for determining whether a half-IF signal is present in the IF signal, and for controlling the receive path to generate a second local oscillation frequency greater than the first local oscillation frequency.