Patent Abstract:
Disclosed is a tuner input circuit. The tuner input circuit includes an integrated including a low noise amplifier and a band pass filter embedded in one chip.

Full Description:
BACKGROUND 
     1. Field of the Invention 
     The disclosure relates to a tuner input circuit, and more particularly to a tuner input circuit in which a low noise amplifier (LNA) and a band pass filter (BPF) allowing a broadcast signal received from an antenna to pass therethrough before inputting to a tuner are integrated with each other in one chip, thereby realizing a device in small size. 
     2. Discussion of the Background 
     In general, static electricity is collected into a human body or machine to raise the potential difference and then suddenly flows toward a lower potential, which is called an electrostatic discharge (ESD). The ESD is to discharge high voltage of about several kV to several tens of kV for a short time of several μs. 
     A device affected by the ESD must be equipped with a protective circuit against the ESD so that the device obtains the resistance against the ESD. For example, when high voltage is applied to a device such as a tuner through an antenna due to the ESD, since the ESD voltage is greater than the internal voltage of a circuit device provided in the tuner, the internal circuits of the tuner may be broken, so that the failure of the tuner may be caused. Accordingly, in order to prevent the failure of the tuner, an ESD protection circuit must be added. 
     In addition, until the signal received through the antenna is input to the tuner, the signal passes through a CB trap, an ESD diode, and an LNA. Since the above devices include capacitors and inductors, the devices may serve as limitation factors in realizing a PCB in micro-size. 
     In addition, the above devices represent different performances due to the difference in a time constant and a pattern therebetween. Further, the interference exists between multi-channels, so that the reliability of the devices must be improved. 
       FIG. 1  is a block diagram showing a tuner input circuit according to the related art. 
     Referring to  FIG. 1 , the tuner input circuit according to the related art includes capacitors connected between an antenna (ANT) and a tuner  200  to cut off a DC component of a signal input from the antenna (ANT), a CB trap  100  to trap a signal having a specific frequency band among signals passing through the capacitors, an EST diode  150  having a cathode connected between the capacitor and the connection terminal of the tuner  200  and an anode connected to the ground, and an LNA  160 . 
     As shown in  FIG. 1 , since the above devices include a plurality of capacitors and a plurality of inductors, the devices occupy the most part of a PCB space. Accordingly, the devices may serve as limitation factors in realizing the device in micro-size. 
     SUMMARY 
     The embodiment of the disclosure provides a tuner input circuit which can be realized in small size by providing an LNA and a BPF in one integrated circuit. 
     According to the embodiment of the disclosure, there is provided a tuner input circuit including an integrated circuit including an LNA and a BPF embedded in one chip. 
     As described above, according to the embodiment of the disclosure, the tuner input circuit can be realized in small size by providing the LNA and the BPF in one integrated circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a tuner input circuit according to the related art; 
         FIG. 2  is a block diagram showing a tuner input circuit according to the embodiment of the disclosure; and 
         FIG. 3  is a graph showing a frequency characteristic of a band pass filter. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, exemplary embodiments of the disclosure will be described in detail with reference to accompanying drawings. The details of other embodiments are contained in the detailed description and accompanying drawings. The advantages, the features, and schemes of achieving the advantages and features of the disclosure will be apparently comprehended by those skilled in the art based on the embodiments, which are detailed later in detail, together with accompanying drawings. The same reference numerals will be assigned to the same elements throughout the whole description. 
       FIG. 2  is a block diagram showing a tuner input circuit according to the embodiment of the disclosure. An integrated circuit  300  according to the embodiment may be formed in the form of a single chip. The integrated circuit  300  may be provided therein with a low noise amplifier (LNA)  340  and a band pass filter (BPF) module  350 . 
     In addition, a signal received through an antenna may passes through an impedance matching module  310 , an electrostatic discharge (ESD) module  320 , and a CB trap  330  before the signal is input into the LNA  340 . The input return loss of −10 dB or more may be satisfied by the impedance matching module  310 . In order to omit additional impedance matching, the length and the thickness of a pattern from the input of an antenna to the integrated circuit  300  may be adjusted, and may be modified according to designs. 
     The ESD module  320  has high voltage of about several kV to about several tens of kV and discharges the voltage for a short time. The ESD module  320  prevents the application of the overvoltage. 
     The signal, which has passed through the ESD module  320 , may be input to the CB trap  330 . The CB trap  330  traps and filters a specific frequency band of a signal which has passed through the ESD module  320 . 
     The impedance matching module  310 , the ESD module  320 , and the CB trap  330  may be selectively formed at the outside of the integrated circuit  300 . 
     The signal, which has passed through the CB trap  330 , is input into the LNA  340 . The LNA  340  selectively operates with the characteristic of a low noise ratio and a high amplification degree and low-noise amplifies an RF signal received from the antenna 
     The LNA  340  selectively operates by DC voltage supplied thereof. If the received RF signal represents a weak electric field, the LNA  340  low-noise amplifies the received RF signal. If the received RF signal represents a strong electric field, the LNA  340  is turned off to by-pass the RF signal. In other words, a by-pass path may be formed at the LNA  340 . 
     The signal, which has passed through the LNA  340 , is input to the BPF module  350 . Since the BPF module  350  cuts off remaining signals except for a signal having a specific frequency band, the frequency band is changed according to the channel selection. Accordingly, the BPF module  350  may communicate with a controller  380  to change the frequency band. The communication scheme may include an international institute of communication (IIC) scheme, but the embodiment is not limited thereto. 
       FIG. 3  is a graph showing a frequency characteristic of a band pass filter. As shown in  FIG. 2 , the band pass filter has a characteristic of passing only one frequency band. The band pass filter has two cutoff frequencies fc 1  and fc 2  serving as upper and lower limit frequencies that may easily pass through the band pass filter. In the case of a narrow frequency band, only the central frequency may be marked. The central frequency may be changed through the communication with the controller  380 . 
     Signals, which have passed through the BPF module  350 , may be distributed by a Balun  360 . The Balun  360  is a passive device to convert a balanced signal into an unbalanced signal, or to convert an unbalanced signal into a balanced signal. The Balun  360  refers to a matching transformer used when feeding power through a coaxial cable. The balanced signal refers to a signal transmitted when the ground surrounds a central signal line like a coaxial cable, and the unbalance signal refers to a signal transmitted when the ground is provided below or at both sides of the signal line like a PCB. 
     As described above, according to the embodiment of the disclosure, the tuner input circuit can be realized in micro-size by providing the LNA and the BPF in one integrated circuit. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Technology Classification (CPC): 7