Abstract:
A TV tuner includes an Ultra High Frequency (UHF)/Very High Frequency (VHF) tracking filter, an UHF/VHF matching circuit and a single conversion Tuner IC. The UHF/VHF tracking filter includes a first Low-Temperature Co-fired Ceramics (LTCC) inductor, a first varactor diode and a fine-tune capacitor electrically connected to determine the maximum gain frequency of the UHF/VHF tracking filter. The UHF/VHF matching circuit includes a second LTCC inductance, a second varactor diodes and a fine-tune capacitor electrically connected to determine the maximum gain frequency of the UHF/VHF matching circuit.

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwan Application Serial Number 95133753, filed Sep. 12, 2006, which is herein incorporated by reference. 
     BACKGROUND 
     1. Field of Invention 
     The present invention relates to a TV tuner and a manufacturing method thereof. More particularly, the present invention relates to an ultra high frequency/very high frequency TV tuner. 
     2. Description of Related Art 
     A TV tuner plays an important role in the digital TV, a Set Top Box and a portable transmitting/receiving communication system. The TV tuner is used to amplify the received radio frequency (RF) signal, select the desired signal and filter out the undesired signal to prevent undesired signals affecting the desired ones. After that, the TV tuner lowers the filtered RF signal to an Intermediate Frequency signal. 
     Because the digital TV needs to be portable, the demands for small digital TVs has increased. However, the air coils used in the TV tuner require a lot of space and need to be plugged in by human hands, which increases the cost and makes portability difficult. 
     For the forgoing reasons, there is a need for a new TV tuner for a small, portable digital TV. 
     SUMMARY 
     According to one embodiment of the present invention, a TV tuner having an Ultra High Frequency (UHF) tracking filter, a UHF matching circuit and a single conversion Tuner IC, characterized in that the UHF tracking filter includes at least one first Low-Temperature Co-fired Ceramics (LTCC) inductor, a first varactor diode and a fine-tune capacitor electrically connected to determine the maximum gain frequency of the UHF tracking filter; the UHF matching circuit includes at least one second LTCC inductor, a second varactor diode and a capacitor electrically connected to determine the maximum gain frequency of the UHF matching circuit. 
     According to another embodiment of the present invention, a TV tuner having a Very High Frequency (VHF) tracking filter, a VHF matching circuit and a single conversion Tuner IC, characterized in that the VHF tracking filter includes at least one first LTCC inductor, a first varactor diode and a fine-tune capacitor electrically connected to determine the maximum gain frequency of the VHF tracking filter; the VHF matching circuit includes at least one second LTCC inductor, a second varactor diode and a capacitor electrically connected to determine the maximum gain frequency of the VHF matching circuit. 
     According to another embodiment of the present invention, a method for manufacturing a TV tuner which has a UHF tracking filter, a UHF matching circuit and a single conversion Tuner IC, characterized in that using LTCC inductors in the UHF tracking filter and the UHF matching circuit to determine the maximum gain frequency; tuning the single conversion Tuner IC for a tuned-voltage, in which the tuned-voltage determines the capacitances of a first varactor diode and a second varactor diode of the UHF tracking filter and the UHF matching circuit respectively; and tuning the capacitance of a fine-tune capacitor of the UHF tracking filter and the inductance of the LTCC inductor of the UHF matching circuit to determine the maximum gain frequency of the UHF tracking filter and the UHF matching circuit. 
     According to another embodiment of the present invention, a method for manufacturing a TV tuner which has a Very High Frequency (VHF) tracking filter, a VHF matching circuit and a single conversion Tuner IC, characterized in that using LTCC inductors in the VHF tracking filter and the VHF matching circuit to determine the maximum gain frequency; tuning the single conversion Tuner IC for a tuned-voltage, wherein the tuned-voltage determines the capacitances of a first varactor diode and a second varactor diode of the VHF tracking filter and VHF matching circuit respectively; and tuning the capacitance of a fine-tune capacitor of the VHF tracking filter and the inductance of the LTCC inductor of the VHF matching circuit to determine the maximum gain frequency of the VHF tracking filter and the VHF matching circuit. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
         FIG. 1  is a TV tuner according to one embodiment of the present invention; 
         FIG. 2A  is an Ultra High Frequency (UHF) tracking filter according to one embodiment of present invention; 
         FIG. 2B  is the frequency response of the UHF tracking filter according to one embodiment of present invention; 
         FIG. 3A  is a UHF matching circuit according to one embodiment of present invention; 
         FIG. 3B  is the frequency response of the UHF matching circuit according to one embodiment of present invention; 
         FIG. 4A  is a Very High Frequency (VHF) tracking filter according to one embodiment of present invention; 
         FIG. 4B  is the frequency response of the VHF tracking filter according to one embodiment of present invention; 
         FIG. 5A  is a VHF matching circuit according to one embodiment of present invention; 
         FIG. 5B  is the frequency response of the VHF matching circuit according to one embodiment of present invention; and 
         FIG. 6  is a single conversion Tuner IC according to one embodiment of present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 1  is a TV tuner according to one embodiment of the present invention. The TV tuner includes an antenna  101 , a pre-amplifier  103 , an Ultra High Frequency (UHF) tracking filter  105 , two second amplifiers  107  and  113 , a UHF matching circuit  109 , a Very High Frequency (VHF) tracking filter  111 , a VHF matching circuit  115  and a single conversion Tuner IC  117 . 
     The antenna  101  is electrically connected to the pre-amplifier  103 , and the pre-amplifier  103  is electrically connected to the UHF tracking filter  105  and the VHF tracking filter  111 . The UHF tracking filter  105 , the second amplifier  107  and the UHF matching circuit  109  are electrically connected, and the VHF tracking filter  111 , the second amplifiers  113  and the VHF matching circuit  115  are also electrically connected. In addition, the UHF matching circuit  109  and the VHF matching circuit  115  are electrically connected to the single conversion Tuner IC  117 . The UHF tracking filter  105 , the UHF matching circuit  109 , the VHF tracking filter  111  and the VHF matching circuit  115  use LTCC inductors instead of air coils. 
       FIG. 2A  is the UHF tracking filter  105  according to one embodiment of the present invention. The UHF tracking filter  105  includes a first varactor diode  213   a , a fine-tune capacitor  215   a  and a first LTCC inductor  209   a . The first end of the first varactor diode  213   a  is connected to the first end of the fine-tune capacitor  215   a , the first end of the first LTCC inductor  209   a  is electrically connected to the second end of the fine-tune capacitor  215   a , the second end of the first LTCC inductor  209   a  is electrically connected to the second end of the first varactor diode  213   a . In addition, capacitors  201   a ,  203   a ,  211   a  and the LTCC inductors  205   a  and  207   a  are electrically connected to the first varactor diode  213   a  and the first LTCC inductor  209   a.    
       FIG. 2B  is the frequency response of the UHF tracking filter  105 . Because the capacitances of the first varactor diode  213   a  and the fine-tune capacitor  215   a  are inversely proportional to the frequency response of the UHF tracking filter  105 , such that the maximum gain frequency of the UHF tracking filter  105  can be tuned by tuning the capacitance of the first varactor diode  213   a  or the fine-tune capacitor  215   a . For example, if the capacitances of the first varactor diode  213   a  and fine-tune capacitor  215   a  increase, the frequency response of the UHF tracking filter  105  decreases from the solid line  201   b  to the dotted line  203   b . As a result, the maximum gain frequency of the UHF tracking filter  105  decreases from  205   b  to  207   b.    
       FIG. 3A  is the UHF matching circuit  109  according to one embodiment of the present invention. The UHF matching circuit  109  includes a second LTCC inductor  305   a , a second varactor diode  313   a  and a capacitor  307   a . The first end of the second varactor diode  313   a  is electrically connected to the first end of the capacitor  307   a , the first end of the second LTCC inductor  305   a  is electrically connected to the second end of the second varactor diode  313   a , and the second end of the second LTCC inductor  305   a  is electrically connected to the second end of the capacitor  307   a . In addition, capacitors  303   a ,  309   a ,  311   a  and resistor  301   a  are electrically connected to the second LTCC inductor  305   a , the second varactor diode  313   a  and the capacitor  307   a.    
       FIG. 3B  is the frequency response of the UHF matching circuit  109 . Because the inductance of the second LTCC inductor  305   a  and the capacitance of the second varactor diode  313   a  are inversely proportional to the frequency response of the UHF matching circuit  109 , such that the maximum gain frequency of the UHF matching circuit  109  can be tuned by tuning the inductance of the second LTCC inductor  305   a  or the capacitance of second varactor diode  313   a . For example, If the inductance of the second LTCC inductor  305   a  or the capacitance of the second varactor diode  313   a  increases, the frequency response of the UHF matching circuit  109  decreases from the solid line  301   b  to the dotted line  303   b . As a result, the maximum gain frequency decreases from  305   b  to  307   b.    
       FIG. 4A  is the VHF tracking filter  111 . The VHF tracking filter  111  includes a first LTCC inductor  405   a , a first varactor diode  413   a  and a fine-tune capacitor  415   a  electrically connected. In addition, there are still other capacitors  401   a ,  411   a  and other inductors  403   a ,  407   a  electrically connected to the first varactor diode  413   a  and the first LTCC inductor  405   a.    
       FIG. 4B  is the frequency response of the VHF tracking filter  111 . Because the capacitances of the fine-tune capacitor  415   a  and the first varactor diode  413   a  are inversely proportional to the frequency response of the VHF tracking filter  111 , such that the maximum gain frequency of the VHF tracking filter  111  can be tuned by tuning the capacitances of the fine-tune capacitor  415   a  and the first varactor diode  413   a.    
     If the capacitances of the fine-tune capacitor  415   a  or the first varactor diode  413   a  increases, the frequency response of the VHF tracking filter  111  decreases from the solid line  401   b  to the dotted line  403   b , such that the maximum gain frequency decreases from  405   b  to  407   b . On the contrary, if the capacitances of the fine-tune capacitor  415   a  or the first varactor diode  413   a  decreases, the frequency response of the VHF tracking filter  111  increases. 
       FIG. 5A  is the VHF matching circuit  115 . The VHF matching circuit  115  includes a second LTCC inductor  503   a , a second varactor diode  509   a  and a capacitor  507   a . The first end of the second varactor diode  509   a  is electrically connected to the first end of the capacitor  507   a , the first end of the second LTCC inductor  503   a  is electrically connected to second end of the capacitor  507   a . In addition, the capacitor  501   a  and LTCC inductor  505   a  are electrically connected to the second LTCC inductor  503   a  and the capacitor  507   a.    
       FIG. 5B  is the frequency response of the VHF matching circuit  115 . Because the inductance of the second LTCC inductor  503   a  is proportional to the frequency response of the VHF matching circuit  115 , so the maximum gain frequency can be tuned by tuning the inductance of the second LTCC inductor  503   a . If the inductance of the second LTCC inductor  503   a  increases, the frequency response moves from the solid line  505   b  to the dotted line  507   b , as a result, the maximum gain frequency increase from the solid line  501   b  to the dotted line  503   b.    
       FIG. 6  is the single conversion Tuner IC  117  according to one embodiment of present invention. The single conversion Tuner IC  117  includes a third varactor diode  615 , a third fine-tune capacitor  617 , a third variable-capacitor  613 , a third LTCC inductor  611  and a third resistor  621 , in which the third fine-tune capacitor  617  is connected in parallel to the third varactor diode  615 . The first end of the third variable-capacitor  613  is electrically connected to the first end of the third varactor diode  615  and the first end of the third fine-tune capacitor  617 . The first end of the third LTCC inductor  611  is electrically connected to the second end of the third variable-capacitor  613 . The second end of the third LTCC inductor  611  is electrically connected to the second end of the third varactor diode  615  and the second end of the third fine-tune capacitor  617 . 
     The first end of the third resistor  621  is electrically connected to the first ends of the third varactor diode  615 , the third fine-tune capacitor  617  and the third variable-capacitor  613 , the second end of the third resistor  621  is electrically connected to a tuned-voltage generating terminal  639 . In addition, the capacitors  601 ,  603 ,  605 ,  607  and  609  are electrically connected to the third varactor diode  615 , the third fine-tune capacitor  617 , the third variable-capacitor  613 , the third LTCC inductor  611  and the resistor  619 . 
     The third variable-capacitor  613  tunes the tuned-voltage such that the tuned-voltage falls within the range of 0 volts to 30 volts, then the third fine-tune capacitor  617  tunes the tuned-voltage slightly. The tuned-voltage tunes the capacitances of the first varactor diode  213   a  and second varactor diode  313   a  of the UHF tracking filter  105  and UHF matching circuit  109  respectively. If the tuned-voltage increases, the capacitances of the first varactor diode  213   a  and the second varactor diode  313   a  decrease. 
     The single conversion Tuner IC  117  further includes a third varactor diode  629 , a third fine-tune capacitor  631 , a third variable-capacitor  633 , a third LTCC inductor  627  and a third resistor  635 . The first end of the third LTCC inductor  627  is electrically connected to the first end of the third variable-capacitor  633 . The second end of the third LTCC inductor  627  is electrically connected to the second end of the third varactor diode  629  and the second end of the third fine-tune capacitor  631 . 
     The second end of the third variable-capacitor  633  is electrically connected to the second end of the third varactor diode  629  and the second end of the third fine-tune capacitor  631 . The first end of the third resistor  635  is electrically connected to the second end of the third variable-capacitor  633 , the second end of the third resistor  635  is electrically connected to a generating terminal of the tuned-voltage  639  with very high frequency. 
     The third variable-capacitor  633  tunes the tuned-voltage such that the tuned-voltage falls within the range of 0 volts to 30 volts, then the third fine-tune capacitor  631  tunes the tuned-voltage slightly. The tuned-voltage tunes the capacitances of the first varactor diode  413   a  and second varactor diode  509   a  of the VHF tracking filter  111  and VHF matching circuit  115  respectively. If the tuned-voltage increases, the capacitances of the first varactor diode  413   a  and the second varactor diode  509   a  decrease. 
     According to the embodiments, the tracking filters and matching circuits of the TV tuner use LTCC inductors instead of air coils, which reduces the volume of the TV tuner such that the digital TV can be portable. In addition, the plugging process of the air coils done by human hands can be omitted, which reduces the cost. 
     Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 USC §112, ¶ 6. In particular, the use of “step of” in the claim herein is not intended to invoke the provisions of 35 USC §112, ¶ 6. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.