SIGNAL RECEIVING DEVICE AND SIGNAL RECEIVING METHOD

• US 20120220250A1
• Filed: 02/24/2012
• Published: 08/30/2012
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Inventors: OCHIAI, Toshiyuki
• Granted Patent: US 9,166,642 B2
• Time in Patent Office: Days
• US Class Current: 455/205
• CPC Class Codes: H03J 1/0008 using a central processing unit, e.g. a microprocessor digital tuning in general H03J5/0245
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03J 3/08 by varying a second parameter simultaneously with the tuning, e.g. coupling bandpass filter
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 2001/1054 by changing bandwidth

Abstract

A signal receiving device and signal receiving method to pass a desired frequency component of an intermediate frequency signal by using an IF filter without increasing a chip area. The signal receiving device comprises: a mixer to mix a received frequency signal with a local oscillation frequency signal to generate an intermediate frequency signal; an IF filter to pass a predetermined frequency component of the intermediate frequency signal; a controlling part which adjusts, according to a frequency band of the intermediate frequency signal, the frequency band of the IF filter, and adjust, according to a center frequency set in the IF filter that fluctuates with the adjustment, a center frequency of the intermediate frequency signal to be inputted in the IF filter; and a demodulating part to demodulate a frequency component of the intermediate frequency signal outputted after passing through the IF filter.

Claims

1. A frequency signal receiving device comprising:

a mixer which mixes a received frequency signal with a local oscillation frequency signal generated by a local oscillator so as to generate an intermediate frequency signal;

an IF filter in which a center frequency of a passable frequency signal and a frequency band are set so as to pass a predetermined frequency component of the intermediate frequency signal;

a controlling part which adjusts, according to a frequency band of the intermediate frequency signal, the frequency band set in the IF filter, and adjusts, according to a center frequency set in the IF filter that fluctuates with the adjustment, a center frequency of the intermediate frequency signal to be inputted in the IF filter; and

a demodulating part which demodulates a frequency component of the intermediate frequency signal outputted after it passes through the IF filter.

2. The frequency signal receiving device according to claim 1, wherein the controlling part adjusts a center frequency of the intermediate frequency signal by adjusting a center frequency of the local oscillation frequency signal.

3. The frequency signal receiving device according to claim 1, wherein the IF filter comprises a resistance and a condenser block that is connected to the resistance and a capacity thereof is switchable;

and

a frequency band set in the IF filter is adjusted by adjusting a capacity value of the condenser block.

4. The frequency signal receiving device according to claim 3, wherein the condenser block comprises a plurality of condensers that are connected in parallel to each other so that connection to the resistance can be selected;

and

a capacity value of the condenser block is adjusted by adjusting the number of the plurality of condensers to be connected to the resistance.

5. The frequency signal receiving device according to claim 1, wherein the IF filter comprises a high-pass filter and a low-pass filter connected in series to each other.

6. The frequency signal receiving device according to claim 2, wherein a capacity value of the condenser block is adjusted on the basis of first information of a fist memory part in which the first information on the number of the plurality of condensers to be connected to the resistance is memorized in advance, to be selected according to a frequency band of the intermediate frequency signal.

7. The frequency signal receiving device according to claim 6, wherein the first memory part is equipped with a plurality of first registers equipped with the first information set for each frequency band of the intermediate frequency signal that is assumed in advance;

and

a capacity value of the condenser block is adjusted on the basis of the first information of the first register selected according to a frequency band of the intermediate frequency inputted.

8. The frequency signal receiving device according to claim 1, wherein a center frequency of the intermediate frequency signal is adjusted based on second information of a second memory part in which memorized in advance is the second information on the center frequency of the intermediate frequency signal to be selected according to a frequency band of the IF filter that is adjusted according to the frequency band of the intermediate frequency signal.

9. The frequency signal receiving device according to claim 8, wherein the second memory part is equipped with a plurality of second registers equipped with the second information set for each frequency band of the intermediate frequency signal that is assumed in advance;

and

a center frequency of the local oscillation frequency signal is adjusted on the basis of the second information of the second register selected according to a frequency band of the intermediate frequency inputted.

10. The signal receiving device according to claim 5, wherein the condenser block in the high-pass filter comprises:

an inputting terminal to receive the intermediate frequency signal;

a connecting terminal to connect to the low-pass filter; and

a plurality of condensers connected in parallel to each other between the inputting terminal and the connecting terminal via a corresponding switch respectively, and

the switch is turned on or off based on a content of a first control input.

11. The signal receiving device according to claim 5 wherein the condenser block in the low-pass filter comprises:

a connecting terminal to connect to the high-pass filter;

an outputting terminal to output the predetermined band signal; and

a plurality of condensers connected in parallel to each other between the connecting terminal and the outputting terminal via a corresponding switch respectively, and

the switch is turned on or off on the basis of a content of the first control input.

16. The frequency signal receiving device according to claim 1 wherein the IF filter comprises a capacity element and a resistance block that is connected to the capacity element and a resistance value is switchable;

and

a frequency band set in the IF filter is adjusted by adjusting a resistance value of the resistance block.

12. A frequency signal receiving method characterized in that it comprises:

a mixer step to mix a frequency signal received with a local oscillation frequency signal generated by a local oscillator so as to generate an intermediate frequency signal;

a filter step to pass a predetermined frequency component of the intermediate frequency signal by an IF filter in which a center frequency of a passable frequency signal and a frequency band are set;

a first adjusting step to adjust a frequency band set in the IF filter according to the frequency band of the intermediate frequency signal;

a second adjusting step to adjust a center frequency of the intermediate frequency signal according to a fluctuation of the center frequency set in the IF filter caused by adjustment of a frequency band set in the IF filter; and

a demodulating step to demodulate the intermediate frequency signal that has passed through the IF filter.

13. The frequency signal receiving method according to claim 12 wherein a center frequency of the intermediate frequency signal is adjusted by adjusting a center frequency of the local oscillation frequency signal outputted from the local oscillator.

14. The frequency signal receiving method according to claim 13 wherein a frequency band set in the IF filter is adjusted based on first information on a frequency band of the IF filter set for each frequency band of the intermediate frequency signal that is assumed in advance.

15. The frequency signal receiving method according to claim 12 wherein a center frequency of the local oscillation frequency signal is adjusted based on second information on a center frequency of the local oscillation frequency signal set for each frequency band of the intermediate frequency signal that is assumed in advance.