CN201341193Y - Electronic tuning unit - Google Patents

Abstract

The utility model relates to an electronic tuning unit for a receiver of a digital terrestrial television, which is respectively connected with an LNB filter circuit, a low-noise amplifier and a signal distribution network according to the signal propagation direction; one output end of the signal distribution network is connected with an RFOUT end and the other output end thereof is connected with a signal selection and filter circuit which is connected with a MAX3580; the MAX3580 is connected with an RC filter circuit; and the output end of the RC filter circuit is connected with a signal output pin. The electronic tuning unit for the receiver of the digital terrestrial television has the advantages of adopting unique ZIF framework and integrated RF tracking filter, leaving external separate filter elements and expensive SAW filter required by the traditional tuning unit based on IF, simplifying peripheral circuit design and being characterized by few peripheral elements, small volume, low power consumption, high integration degree, no debugging, good informality, high reliability and the like.

Description

Electronic tuning unit

Technical field

The utility model relates to a kind of electronic tuning unit, the electronic tuning unit that a kind of specifically ground digital television receiver is used.

Background technology

Digital television receiver is that top box of digital machine will receive the TV signal of transmitting in the space system, must be chosen in corresponding channel in 170MHz to the 850MHz frequency band through tuner, through low-converter radiofrequency signal being become intermediate-freuqncy signal again sends into the lower part circuit and handles, its output is analog signal, tuning and converter plant just is collectively referred to as traditional tuner, i.e. electronic tuning unit.Technology from existing digital television receiver, all have one tuning, down-conversion QAM demodulation, MPEG II separate the process of ginseng sign indicating number, and this plurality of processes is at present by independent devices and circuit are realized respectively separately, that is to say that the overall process that receives last digital bit stream output from analog signal realizes by the several separate device is common.

Simultaneously according to the delivering path difference, Digital Television can be divided into three kinds on terrestrial wireless (DVB-T), wired (DVB-C) and satellite (DVB-S) again.The GB 20600-2006 " digital television ground broadcast transmission system frame structure, chnnel coding and modulation standard " of National Standards Commission's issue in 2006 is exactly the terrestrial wireless standard, is exactly by the television tower emission, and the user is the sort of with the antenna reception.Be intended to replace Europe superscript DVB-T, set up the digital TV ground transmission standard of a cover China oneself.Though GB DMB-T comes into effect, most enterprises still extensive exploitation meet the electronic tuning unit of Europe superscript DVB-T, and it is less to adapt to the electronic tuning unit research of GB DMB-T.

The utility model content

The purpose of this utility model is to provide a China digital TV ground transmission standard DMB-T that meets, and is simple in structure, the digital television receiver electronic tuning unit that cost is low.

The utility model is achieved in that

A kind of electronic tuning unit, be connected with the LNB filter circuit respectively according to signal propagation direction, low noise amplifier, signal distribution network, an output of signal distribution network connects the RFOUT end, and another output connects signal and selects filter circuit, and signal selects filter circuit to link to each other with MAX3580, MAX3580 is connected with the RC filter circuit, and the output of RC filter circuit connects the signal output pin.

Further scheme is: the output of signal selection filter circuit is connected with MAX3580 with the 4th pin by the 3rd pin of MAX3580.

Further scheme is: described MAX3580 also is connected with the RFAGC input circuit, IFAGC input circuit, I2C telecommunication circuit, reference frequency oscillating circuit, MAX3580 power supply filter circuit, PLL loopfilter circuit.

The utility model Digital Television has been to adopt unique Z IF framework and integrated RF tracking filter with receiver with the advantage of electronic tuning unit, saved tradition based on needed external discrete filter element of the tuner of IF and expensive SAW filter, simplified periphery circuit design, had that peripheral cell is few, volume is little, low in energy consumption, characteristics such as integrated level is high, exempt from debugging, good product consistency, reliability height.

Description of drawings

Fig. 1: the utility model theory diagram;

Fig. 2: the utility model circuit connection diagram.

Embodiment

Below in conjunction with accompanying drawing the utility model is described further:

Shown in accompanying drawing 1,2, a kind of electronic tuning unit amplifies the back frequency-selecting with input signal, then with the local oscillator mixing after the I of output zero intermediate frequency, Q signal.Its signal input part connects the input of LNB filter circuit and low noise amplifier, the output of low noise amplifier connects the input of signal distribution network, an output of signal distribution network connects the RFOUT end, another output connects the input that signal is selected filter circuit, signal selects an output of filter circuit to connect the 3rd pin of MAX3580, another output connects the 4th pin of MAX3580, the I of MAX3580, the Q output pin connects the input of RC filter circuit, the output of RC filter circuit connects the I of this tuner, the Q output pin also comprises the RFAGC input circuit, the IFAGC input circuit in addition, the I2C telecommunication circuit, the reference frequency oscillating circuit, MAX3580 power supply filter circuit, PLLloop filter circuit.The concrete connection is: C1, and C2, C3, C4, L1 forms the LNB filter circuit; R1, R2, R3, R4, R5, R6, R7, C6, L3, Q1 forms low noise amplifier, C7, C8, C9, C10, C11, CD1 forms the electric source filter circuit of low noise amplifier; R8, R9, R10, R11 forms signal distribution network; C14, C15, C16, C17, C18, L3, L4 form input signal and select filter circuit; C29, C31, C33, C35, R14, R15, R16, R17, R18, R19, R20, R21 forms I, Q output filter circuit; C25, R12, R13, Q2 forms the RFAGC input circuit; C36, R22 forms the IFAGC input circuit; C41, C42, R24, R25 forms the I2C telecommunication circuit; C46, C47, C48, X1 forms the reference frequency oscillating circuit, C19, C20, C21, C22, C23, C26, C27, C37, C38, C42, C43, C44, C45, CD2 form MAX3580 power supply filter circuit; C39, C40, R23 form PLL loop filter circuit.Concrete annexation is: RFIN connects inductance L 1 one ends and capacitor C 5 one ends; Inductance L 1 other end connects LNB, C1 wherein in parallel, and C2, C3, C4 is to ground filtering; Capacitor C 5 other ends connect triode Q1 base stage, and resistance R 1, R2, R6 one end; The R6 other end connects capacitor C 6 one ends; R2 one end connects inductance L 2 one ends, resistance R 3 one ends; Resistance R 3 other ends are connected to+5V, connect filter capacitor C7 simultaneously, C8, C9, C10, C11, CD1; Inductance L 2 other ends connect C6, C12, R7 one end; The R7 other end connects the collector electrode of triode Q1; R4, R5 connects the emitter of triode Q1; The C12 other end connects resistance R 8 one ends; The R8 other end connects resistance R 9, R11 one end; The R9 other end connects resistance R 10, C13 one end; The C13 other end connects RFOUT; The R11 other end connects capacitor C 14, C17 one end; The C14 other end connects capacitor C 15 1 ends and inductance L 3 one ends; Inductance L 3 is connected the 3rd pin (VHFIN) of capacitor C 16 and MAX3580 with the C15 other end; The C17 other end connects inductance L 4 one ends and capacitor C 18 1 ends; Capacitor C 18 other ends connect the 4th pin (UHF_IN) of MAX3580; The 1st pin of MAX3580 connects R24 one end; The R24 other end connects the SDA terminal; MAX3580 the 2nd pin connects resistance R 25 1 ends; The R25 other end connects the SCL terminal; The 5th, 6 pin of MAX3580 connect ground; The 7th, 14,20,26,30 of MAX3580 connects power supply+3.3V; The 8th pin of MAX3580 connects inductance L 6 one ends; Inductance L 6 other ends connect power supply+3.3V; + 3.3V connects filter capacitor C19, C20, C21, C22, C23, C24, C26, C27, C37, C38, C42, C43, C44, C45, CD2 to ground; MAX3580 the 9th pin connects the emitter of resistance R 12 1 ends and triode Q2; Resistance R 12 other ends connect power supply+3.3V; The collector electrode of triode Q2 connects ground; The base stage of triode Q2 connects capacitor C 25 to ground, connects R13 one end; The R13 other end connects the IF_AGC input terminal; MAX3580 the 10th pin connects inductance L 5 one ends; Inductance L 5 other ends connect MAX3580 the 11st pin; MAX3580 the 12nd pin is unsettled; MAX3580 the 13rd pin is unsettled; MAX3580 the 15th pin connects capacitor C 28 1 ends; Capacitor C 28 other ends connect resistance R 14 1 ends; Resistance R 14 other ends connect capacitor C 29 and resistance R 15 1 ends; Resistance R 15 other ends connect the QN_OUT lead-out terminal; MAX3580 the 16th pin connects capacitor C 30 1 ends; Capacitor C 30 other ends connect resistance R 16 1 ends; Resistance R 16 other ends connect capacitor C 31 and resistance R 17 1 ends; Resistance R 17 other ends connect the QP_OUT lead-out terminal; MAX3580 the 17th pin connects capacitor C 32 1 ends; Capacitor C 32 other ends connect resistance R 18 1 ends; Resistance R 18 other ends connect capacitor C 33 and resistance R 19 1 ends; Resistance R 19 other ends connect the IN_OUT lead-out terminal; MAX3580 the 18th pin connects capacitor C 34 1 ends; Capacitor C 34 other ends connect resistance R 20 1 ends; Resistance R 20 other ends connect capacitor C 35 and resistance R 21 1 ends; Resistance R 21 other ends connect the IP_OUT lead-out terminal; MAX3580 the 19th pin connects capacitor C 36 and resistance R 22 1 ends; Resistance R 22 other ends connect the IF_GC input terminal; MAX3580 the 21st connects resistance R 23 1 ends, capacitor C 40 1 ends and MAX3580 the 24th pin; Capacitor C 40 other ends connect ground; Resistance R 23 other ends connect capacitor C 39 1 ends; Capacitor C 39 other ends connect ground; MAX3580 the 22nd pin connects ground; MAX3580 the 23rd pin connects capacitor C 41 1 ends; Capacitor C 41 other ends connect ground; MAX3580 the 25th pin connects ground; MAX3580 the 27th pin connects ground; MAX3580 the 28th pin is unsettled; MAX3580 the 29th pin is unsettled; MAX3580 the 31st pin connects capacitor C 46 1 ends and capacitor C 48 1 ends; Capacitor C 46 other ends connect crystal X1 one end; The crystal X1 other end connects ground; Capacitor C 48 other ends connect MAX3580 the 32nd pin and capacitor C 47 1 ends; Capacitor C 47 other ends connect ground.

Claims (3)

1, a kind of electronic tuning unit, be connected with the LNB filter circuit respectively according to signal propagation direction, low noise amplifier, signal distribution network, an output that it is characterized in that signal distribution network connects the RFOUT end, and another output connects signal and selects filter circuit, and signal selects filter circuit to link to each other with MAX3580, MAX3580 is connected with the RC filter circuit, and the output of RC filter circuit connects the signal output pin.

2, electronic tuning unit according to claim 1 is characterized in that: the output of described signal selection filter circuit is connected with MAX3580 with the 4th pin by the 3rd pin of MAX3580.

3, electronic tuning unit according to claim 1 and 2 is characterized in that: described MAX3580 also is connected with the RFAGC input circuit, the IFAGC input circuit, the I2C telecommunication circuit, the reference frequency oscillating circuit, MAX3580 power supply filter circuit, PLL loop filter circuit.