CN201045760Y

CN201045760Y - Digital television radio frequency power amplifier

Info

Publication number: CN201045760Y
Application number: CNU200720124399XU
Authority: CN
Inventors: 孙寿根; 陈亚非
Original assignee: CHONGQING HONGSHEN MODERN VIDEO & AUDIO TECHNOLOGY Co Ltd
Current assignee: CHONGQING HONGSHEN MODERN VIDEO & AUDIO TECHNOLOGY Co Ltd
Priority date: 2007-05-31
Filing date: 2007-05-31
Publication date: 2008-04-09
Anticipated expiration: 2017-05-31

Abstract

The utility model relates to a digital television radio frequency power amplifier, which comprises a radio frequency signal amplifying circuit, a constant current circuit, an isolator, a power circuit, and a heat dissipation circuit. The radio frequency signal amplifying circuit forms three-level amplifying by linear power amplification circuits with three power levels which are 10mw, 50mw and 200mw which are connected in sequence, the first level adapts a radio frequency amplification integrated circuit with power multiplication level, the second level and the third level linear power amplification circuits adapt radio frequency linear power tubes which are respectively connected with corresponding input and output matching circuits, and realize the amplifying function at each power level. The second level and the third level linear power amplification circuits are further connected with the respective constant current circuit, the output end of the third level linear power amplifying circuit is connected with the isolator and is output by the isolator finally. The utility model has the advantages that the utility model can meet amplifying and outputting of the linear and nonlinear radio frequency signal with smaller distortion under the various standard requirements of digital televisions, and adopts normal radio frequency cable as a power distribution synthesizer in the UHF frequency band simultaneously, and the cost is reduced, and the reliability is high.

Description

The Digital Television radio-frequency power amplifier

Technical field

The utility model relates to the power amplifier in the digital TV field, particularly to a kind of power amplification circuit of the Standard Digital Television radiofrequency signal of 200mw magnitude.

Background technology

At present, the visual plant that receives as Digital Television in China---concentrate signal source, the mode that more powerful Digital Television radio-frequency signal source wherein and power amplifier thereof all need to take import.For radio-frequency power amplifier wherein, if adopt domestic common on the market power amplifier as an alternative, then can not satisfy the working band height, the requirement of the very little and high reliability of the additional distortion of linearity and nonlinear distortion particularly will be satisfied the requirement that also can obtain the very little Digital Television radiofrequency signal of high reliability, stable, high-quality linearity and nonlinear distortion uhf band high-end.For this reason, the present utility model a kind of radio-frequency power amplifier can satisfy above requirement, can substitute the Digital Television radio-frequency power amplifier of import.

Summary of the invention

The purpose of this utility model is to overcome at present domestic common on the market power amplifier in the deficiency that is applied in the amplification of Digital Television radio-frequency power, provide a kind of energy reliably working in the Digital Television radio-frequency power amplifier of arbitrary channel of VHF, UHF, satisfied linear and the very little demand on signal quality of nonlinear distortion.

The utility model is achieved through the following technical solutions;

The radio-frequency power amplifier that is used for Digital Television of the present utility model comprises rf signal amplification circuit, constant-current circuit, isolator, power circuit and heat radiation circuit.Wherein rf signal amplification circuit is formed three grades of amplifications by the 10mw, the 50mw that connect in regular turn, the linear power amplification circuit of three power levels of 200mw, the first order adopts the radio frequency amplification circuit of PD level, and this first order amplifying circuit is all general at VHF, uhf band.When being used for the VHF frequency range, second and third of this power amplifier grade linear power amplification circuit adopts the RF linear power tube to connect mutually deserved I/O match circuit separately and realizes enlarging function under each power level, and the output of last linear power amplification circuit is exported through isolator.When being used for uhf band, the second level linear power amplification circuit of this power amplifier adopts the RF linear power tube to connect corresponding I/O match circuit, realize the enlarging function under the power level, in the trilinear power amplification circuit, because residing power level is higher, need to adopt traditional power division synthetic technology, the utility model adopts common radio frequency cable to replace expensive three-dB coupler commonly used as power distributing circuit and power synthesis circuit, power distributing circuit connects the Digital Television radiofrequency signal from the second linear power amplification circuit 50mw, it is divided into two paths of signals, import linear power amplification circuit separately, the output signal of linear power amplification circuit is connected to power synthesis circuit, this two-way radiofrequency signal exports isolator to again after power synthesis circuit is synthetic, export through isolator.

Described constant-current circuit is made up of a current sampling circuit, an operational amplifier and an emitter follower on the collector electrode branch road that is connected the RF linear power tube.Described constant-current circuit, their relation is the current sampling circuit in second (or 3rd) linear power amplification circuit, give and give an emitter follower again after operational amplifier amplifies, and then turn back in second (or 3rd) linear power amplification circuit by emitter follower.

Described linear power amplification circuit is made up of an attenuator, an input matching circuit, a transistor and an output matching circuit, wherein the output of attenuator connects input matching circuit, radiofrequency signal through the output of upper level linear power amplification circuit is imported from attenuator, the output of input matching circuit is connected to transistor base, and transistor collector links to each other with output matching circuit.

Described input matching circuit is transformed to 50 Europe with transistorized input impedance, and output matching circuit is transformed to 50 Europe with the output impedance of amplifier at the corresponding levels, and input matching circuit and output matching circuit all need conjugate impedance match.

Advantage of the present utility model is to realize to satisfy the various standards of Digital Television and requires linearity down and the less radiofrequency signal power amplification of nonlinear distortion to export, can substitute the Digital Television radio-frequency power amplifier of import, thereby can reduce import with quasi-instrument, save foreign exchange, improve the production domesticization that Digital Television is produced.Simultaneously when uhf band, adopt common radio frequency cable, compare with the power division synthesizer of general general 3dB cable and draw materials easily as the power division synthesizer, cheap, for its 1/50th, the reliability height.

Description of drawings

In conjunction with the embodiments the utility model is further described with reference to the accompanying drawings.

Fig. 1 is the circuit block diagram of the utility model radio-frequency power amplifier.

Fig. 2 is the transistor power amplifier schematic diagram in the utility model radio-frequency power amplifier.

Fig. 3 is the utility model constant-current circuit figure.

Fig. 4 is the circuit block diagram of the utility model trilinear power amplification circuit at uhf band.

Embodiment

Referring to Fig. 1, this radio-frequency power amplifier comprises three grades of linear power amplification circuits 1,2,3, constant-current circuit 4,5, isolator 6, power circuit 7 and the heat radiation circuit 8 that is electrically connected in regular turn.Wherein first order linear power amplification circuit 1 adopts the radio frequency amplification circuit of PD level, when being used for the VHF frequency range, second and third of this power amplifier grade linear power amplification circuit 2,3 adopts the RF linear power tubes to connect corresponding I/O match circuit separately and realizes enlarging function under each power level, and the output of last linear power amplification circuit 3 is through isolator 6 outputs.

When being used for uhf band, the second level linear power amplification circuit 2 of this power amplifier adopts the RF linear power tube to connect corresponding I/O match circuit, realize the enlarging function under the power level, in trilinear power amplification circuit 3, because residing power level is higher, need to adopt traditional power division synthetic technology, the utility model adopts common radio frequency cable to replace expensive three-dB coupler commonly used as power distributing circuit and power synthesis circuit, see Fig. 4, the Digital Television radiofrequency signal that power distributing circuit 13 connects from the second linear power amplification circuit 50mw, it is divided into two paths of signals, import linear power amplification circuit 14 separately, 15, linear

power amplification circuit

14,15 output signal is connected to power synthesis circuit 16, this two-way radiofrequency signal exports isolator 6 to again after power synthesis circuit 16 synthesizes, export through isolator.

Referring to Fig. 2, more than the VHF frequency range adopt second, three grades of linear power amplification circuits 2,3, the linear

power amplification circuit

15 and 14 that adopts in the second level linear power amplification circuit 2 that uhf band adopts and the third level all is by an attenuator 9, one input matching circuit 10, one transistor 11 and an output matching circuit 12 are formed, wherein the output of attenuator 9 connects input matching circuit 10, radiofrequency signal through the output of upper level linear power amplification circuit is imported from attenuator 9, the output of input matching circuit 10 is connected to the ground level of transistor 11, and the collector electrode of transistor 1 links to each other with output matching circuit 12.

Referring to Fig. 3, second and third grade linear power amplification circuit 2 also is connected constant-current circuit 4,5 respectively separately with 3, constant-current circuit 4,5 is made up of current sampling circuit on the collector electrode branch road of the RF linear power tube that is connected linear power amplification circuit 19, an operational amplifier 18 and an emitter follower 17, current sampling circuit 19 obtains the linear power amplification circuit current signal, concatenation operation amplifier 18, after amplifying, connect emitter follower 17 again, and then turn back in the linear power amplification circuit by emitter follower 17.

Power circuit 7 provides electric energy for full machine circuit, and heat radiation circuit 8 is this power amplifier circuit heat radiation.Foregoing circuit is with the solid-state circuit form, adopts the circuit board of particular medium, realizes with PCB (printed circuit board (PCB)) form.

More than the feature and the correlation of each part as described below:

First order linear power amplification circuit 1 to 10mw, exports the power amplification of the Digital Television radiofrequency signal low distortion of the 0.2mw (100dB μ/50 Ω) of the outer input of machine to late-class circuit, and promptly second level linear power amplification circuit 2.

The radiofrequency signal of 10mw is input in the second level linear power amplification circuit 2, at first by attenuator 9, be transported to the base stage of transistor 11 through input matching circuit 10 then, the collector electrode by transistor 11 is transported to output matching circuit 12, and output is amplified to the 50mw radiofrequency signal.

Then be input to the third level linear power amplification circuit 3 from the 50mw radiofrequency signal of second level linear power amplification circuit 2 outputs, same earlier by attenuator 9, be transported to the base stage of transistor 11 then through input matching circuit 10, collector electrode by transistor 11 is transported to output coupling 12 circuit, this input, output matching circuit be according to the difference of VHF or UHF working channel, and need do corresponding configuration and adjustment.At uhf band, the utility model adopts common radio frequency cable to replace the expensive three-dB coupler rate of doing work commonly used to distribute synthesizer, the power division synthesizer that this is made up of common radio frequency cable, under each working channel of UHF, will be by power distributing circuit 13 from the Digital Television radiofrequency signal of the second linear power amplification circuit 50mw, be divided into two paths of signals, import linear

power amplification circuit

14 and 15 separately, 14 and 15 output signal outputs to power synthesis circuit more separately, this two-way radiofrequency signal exports late-class circuit (the power division synthesizer of common radio frequency cable to again after power synthesis circuit is synthetic, be power divider when being used in power division, be used in and be power combiner when power synthesizes.) output is amplified to the low distortion radiofrequency signal of 200mw.

Export by an isolator 6 from the 200mw radiofrequency signal that 3 outputs of third level linear power amplification circuit are amplified more than the 32dB, to guarantee that exporting return loss meets specification requirement.

Input matching circuit is transformed to 50 Ω with transistorized extremely low input impedance in the circuit of wherein second and third grade linear power amplification circuit 2,3, make amplifier obtain maximum exciting power from signal source, and output matching circuit is transformed to 50 Ω with the output impedance of amplifier at the corresponding levels, is transferred to the power maximum of load to guarantee amplifier.Input matching circuit and output matching circuit are conjugate impedance match, so that can make input and output can obtain maximum through-put power.

Constant-current circuit 4 or 5 makes the collector current of second and third grade linear power amplification circuit 2,3 constant, and is stable with the radio-frequency performance that guarantees second and third grade linear power amplification circuit 2,3.

Claims

1. Digital Television radio-frequency power amplifier, comprise rf signal amplification circuit, constant-current circuit (4,5), isolator (6), power circuit (7) and heat radiation circuit (8), it is characterized in that: rf signal amplification circuit is by the 10mw that connects in regular turn, 50mw, the linear power amplification circuit of three power levels of 200mw is formed three grades of amplifications, the first order adopts the radio frequency amplification circuit (1) of PD level, second, three grades of linear power amplification circuits (2,3) adopting the RF linear power tube to connect corresponding I/O match circuit separately forms, realize the enlarging function under each power level, second, three grades of linear power amplification circuits (2,3) also with separately constant-current circuit (3,4) connect, the output of third level linear power amplification circuit (3) connects isolator (6), exports through isolator; Power circuit (7) is given the circuit supply of full machine.

2. Digital Television radio-frequency power amplifier, comprise rf signal amplification circuit, constant-current circuit, isolator (6), power circuit (7) and heat radiation circuit (8), it is characterized in that: rf signal amplification circuit is formed three grades of amplifications by the 10mw, the 50mw that connect in regular turn, the linear power amplification circuit of three power levels of 200mw; The first order adopts the radio frequency amplification circuit (1) of PD level; The second level adopts RF linear power tube (2) to connect corresponding I/O match circuit, realizes the enlarging function under the power level, and second level linear power amplification circuit also connects by constant-current circuit (3); Third level linear power amplification circuit adopts common radio frequency cable as power distributing circuit and power synthesis circuit, power distributing circuit (13) connects the Digital Television radiofrequency signal from the second linear power amplification circuit 50mw, it is divided into two paths of signals, import linear power amplification circuit (14,15) separately, the output signal of linear power amplification circuit (14,15) is connected to power synthesis circuit (16), this two-way radiofrequency signal exports isolator (6) to again after power synthesis circuit (16) is synthetic, export through isolator; Power circuit (7) is given the circuit supply of full machine.

3. Digital Television radio-frequency power amplifier according to claim 1 and 2, it is characterized in that described constant-current circuit is made up of a current sampling circuit (19), an operational amplifier (18) and an emitter follower (17) on the collector electrode branch road of the RF linear power tube that is connected linear power amplification circuit, current sampling circuit (19) obtains the linear power amplification circuit current signal, concatenation operation amplifier (18), after amplifying, connect emitter follower (17) again, and then turn back in the linear power amplification circuit by emitter follower (17).

4. Digital Television radio-frequency power amplifier according to claim 1 and 2, it is characterized in that described linear power amplification circuit is made up of an attenuator (9), an input matching circuit (10), a transistor (11) and an output matching circuit (12), wherein the output of attenuator (9) connects input matching circuit (10), radiofrequency signal through the output of upper level linear power amplification circuit is imported from attenuator (9), the output of input matching circuit (10) is connected to the ground level of transistor (11), and the collector electrode of transistor (1) links to each other with output matching circuit (12).

5. Digital Television radio-frequency power amplifier according to claim 4, it is characterized in that described input matching circuit (10) is transformed to 50 Europe with the input impedance of transistor (10), output matching circuit (12) is transformed to 50 Europe with the output impedance of amplifier at the corresponding levels, and input matching circuit and output matching circuit are conjugate impedance match.