CN103997221B - A kind of multiple-channel output direct current DC converter and corresponding radio frequency units - Google Patents

Abstract

An embodiment of the present invention provides a multi-output DC-DC converter, including: a primary side conversion circuit, a transformer, and at least two secondary side conversion circuits; wherein, the primary side conversion circuit and the at least two secondary side conversion circuits The circuits are coupled through a transformer, and the at least two secondary side conversion circuits are coupled with each other through a transformer; the primary side conversion circuit includes at least a first switch tube and a second switch tube; by adjusting the first switch tube According to the duty ratio of the second switching tube, the output voltages of the two secondary conversion circuits can be adjusted. Correspondingly, the embodiment of the present invention also provides a corresponding wireless radio frequency unit. By implementing the embodiment of the present invention, the performance of the converter can be improved, its cost and volume can be reduced, and the reliability and lifespan of the radio frequency unit can be improved.

Description

A multi-output DC-DC converter and corresponding wireless radio frequency unit

technical field

The invention relates to the technical field of power supplies of wireless base stations, in particular to a multi-channel output DC-DC converter and a wireless radio frequency unit using the corresponding converter.

Background technique

The application environment of the radio frequency unit (Radio Remote Unit, RRU) of the wireless base station is basically outdoors, the working environment is relatively harsh, and the temperature range may be very wide (for example, it can reach the range of -40°C to 55°C). Inside the RRU, the temperature can sometimes even be as high as 100°C. Therefore, the power supply inside the RRU may have problems such as service life and reliability in a high-temperature environment. Therefore, it is necessary to adopt a power supply technical solution with a simple circuit structure and good high-temperature performance inside the RRU.

As shown in FIG. 1 , it is a schematic block diagram of an existing DC converter applied to a wireless base station. In this technical solution, the input 48V direct current is converted into 30V and 5.5V direct current by two isolation converters, and supplied to the power amplifier circuit and the digital circuit respectively. However, due to the adoption of two isolation converters in this scheme, large-capacity filter capacitors are required at the B and C ports. In particular, the filter capacitor used at port B connected to the power amplifier circuit requires relatively high voltage (above 50V) and relatively large capacity (thousands of microfarads), and generally needs to use aluminum electrolytic capacitors; and aluminum electrolytic capacitors are large in size and can be used at high temperatures. The lower service life is limited; in addition, because energy cannot flow between ports B and C, each port must be designed according to the requirements of maximum load, dynamic and hold time, resulting in high circuit cost and large volume.

As shown in FIG. 2 , it is a schematic block diagram of another existing DC converter applied to a wireless base station. In this technical solution, a non-isolated step-down (BUCK) converter is used to replace an isolated converter in Technology 1, so the overall cost and volume of the circuit are relatively reduced, but it still requires two independent converter. At the same time, due to the one-way flow of energy from port B to port C, the filter capacitance of port C can be reduced, and the dynamic performance of port C can be improved, because the energy of port C is obtained from port B, and port B is Regulated stable voltage. However, because energy cannot flow from port C to port B, port B still needs a large-capacity aluminum electrolytic capacitor, and the dynamic performance of port B cannot be improved, because the energy of port B is obtained from port A, and the voltage obtained at port A is An unstable voltage that is not regulated.

Contents of the invention

The technical problem to be solved by the embodiments of the present invention is to provide a multi-output DC-DC converter and a corresponding wireless radio frequency unit, which can realize bidirectional flow of energy between multiple outputs, and reduce or remove large-capacity electrolytic capacitors The use of the converter enables the converter to be applied in a high temperature environment, improving the service life and reliability.

In order to solve the above technical problems, an embodiment of the present invention provides a multi-output DC-DC converter for powering a wireless radio frequency unit, including:

The primary conversion circuit is connected with a DC input power supply;

At least two secondary conversion circuits, wherein the first secondary conversion circuit is used for rectification and conversion, and the first DC power obtained after conversion is output to the power amplifier circuit connected to it, and the second secondary conversion circuit is used for rectification transforming, and outputting the transformed second DC power supply to a digital circuit connected thereto;

The transformer has a primary winding and at least two secondary windings, the primary winding is connected to the primary conversion circuit, and the first secondary conversion circuit and the second secondary conversion circuit are respectively connected to a secondary winding;

Wherein, the primary conversion circuit and the at least two secondary conversion circuits are coupled through a transformer, and the at least two secondary conversion circuits are coupled to each other through a transformer, so that the energy in the two secondary conversion circuits transfer between each other;

The primary conversion circuit includes at least a first switch tube and a second switch tube, and the first DC power supply and the second switch tube can be adjusted by adjusting the duty ratio of the first switch tube and the second switch tube. 2. The voltage of the DC power supply;

Wherein, the primary-side conversion circuit includes a step-down voltage stabilizing conversion circuit composed of a filter capacitor, a first switch tube, a second switch tube, a first inductor and a first capacitor, and a third switch tube, a fourth switch tube A DC/AC conversion circuit composed of a tube and the primary winding of the transformer;

Wherein, the filter capacitor is connected in parallel with the DC input power supply, its anode is connected to the drain of the first switch tube, and the source of the first switch tube is connected to one end of the first inductor and the drain of the second switch tube, so The other end of the first inductance is connected to the positive pole of the first capacitor and the middle tap of the primary winding of the transformer, the source of the second switching tube, the negative pole of the first capacitor, the source of the third switching tube, the fourth switch The source of the tube is connected to the negative pole of the filter capacitor, and the drain of the third switch tube and the drain of the fourth switch tube are respectively connected to one end of the primary winding of the transformer;

Wherein, it further includes an isolated feedback control circuit, one end of which is connected to the positive pole of the fourth capacitor, and is used to transmit a corresponding pulse width modulation signal to the gate of the first switching tube, and the isolated feedback control circuit further includes:

A sampling voltage comparison amplifier circuit, configured to divide the voltage sampled from the positive electrode of the second capacitor and then compare it with a reference voltage and amplify it;

A pulse width modulation circuit, used to compare the amplified signal from the sampling voltage comparison amplifier circuit with a predetermined sawtooth wave signal, and generate a pulse width modulation signal;

The isolation circuit at least includes an optocoupler, configured to transmit the pulse width modulation signal generated by the pulse width modulation circuit to the gate of the first switch tube;

Wherein, the first secondary side conversion circuit includes a fifth switch tube, a sixth switch tube and a second capacitor;

Wherein, the anode of the second capacitor is connected to the center tap of the first secondary winding of the transformer, the source of the fifth switching transistor and the source of the sixth switching transistor are connected to the negative electrode of the second capacitor, and the The drain of the fifth switch tube and the drain of the sixth switch tube are respectively connected to one end of the first secondary winding of the transformer, and both ends of the second capacitor are connected to a power amplifier circuit.

Preferably, the second secondary side conversion circuit includes a seventh switch tube, an eighth switch tube and a third capacitor;

Wherein, the anode of the third capacitor is connected to the center tap of the second secondary winding of the transformer, the source of the seventh switching transistor and the source of the eighth switching transistor are connected to the negative electrode of the third capacitor, and the The drain of the seventh switch tube and the drain of the eighth switch tube are respectively connected to one end of the second secondary winding of the transformer, and both ends of the third capacitor are connected to a digital circuit.

Preferably, the first switch tube and the second switch tube have complementary duty ratios, the duty ratios of the third switch tube and the fourth switch tube are both 50%, and the third switch tube The switching tube is switched synchronously with the fifth switching tube and the seventh switching tube, and the fourth switching tube is switched synchronously with the sixth switching tube and the eighth switching tube.

Preferably, the first secondary side conversion circuit includes a full-bridge rectifier circuit composed of a ninth switch tube, a tenth switch tube, an eleventh switch tube, and a twelfth switch tube;

Wherein, the first end of the first secondary winding of the transformer is connected to the source of the ninth switching transistor and the drain of the eleventh switching transistor, and the second end of the first secondary winding of the transformer is connected to the first The source of the tenth switch tube, the drain of the twelfth switch tube, the drains of the ninth switch tube and the tenth switch tube are connected to the positive pole of the fourth capacitor, and the source of the eleventh switch tube pole, and the source of the twelfth switch tube are connected to the negative pole of the fourth capacitor.

Preferably, the third capacitor is a large-capacity low-voltage capacitor, and the second capacitor and the fourth capacitor are high-voltage aluminum electrolytic capacitors.

Correspondingly, an embodiment of the present invention also provides a wireless radio frequency unit, which adopts the aforementioned multi-output DC-DC converter, one output of the multi-output DC-DC conversion is connected to a power amplifier circuit, and the other output is connected to a digital circuit .

Implementing the embodiment of the present invention has the following beneficial effects:

In the embodiment provided by the present invention, only one independent isolation converter is used and the duty ratio of the first switching tube in the primary side conversion circuit is adjusted, so that the voltage regulation and voltage regulation of the output port of the first secondary side conversion circuit can be realized ;

At the same time, the bidirectional flow of energy between the first secondary conversion circuit and the second conversion circuit can be realized, so that the voltage at the output port of the second conversion circuit and the voltage at the output port of the first secondary conversion circuit maintain a fixed ratio and stabilize the voltage, and When adjusting the voltage of the output port of the first secondary conversion circuit, the voltage of the output port of the second secondary conversion circuit is changed accordingly, which can further improve the dynamic response performance of the first secondary conversion circuit and prolong the second secondary conversion circuit. The voltage holding time of the side conversion circuit;

Moreover, through the two-way flow of energy between the first secondary conversion circuit and the second conversion circuit, it is also possible to reduce or remove the large-capacity electrolytic capacitor of the first secondary conversion circuit, and only use small-capacity ceramic capacitors, so that Reduce cost and volume, and improve system reliability and life.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For a person of ordinary skill in the art, obtaining other drawings based on these drawings still belongs to the scope of the present invention without any creative effort.

FIG. 1 is a schematic block diagram of an existing DC converter applied to a wireless base station;

FIG. 2 is a schematic block diagram of another existing DC converter applied to a wireless base station;

Fig. 3 is a block diagram of an embodiment of the multi-channel output DC-DC converter provided by the present invention;

Fig. 4 is a circuit schematic diagram corresponding to an embodiment of the multi-channel output DC-DC converter in Fig. 3;

5 is a schematic diagram of the first secondary conversion circuit in another embodiment of the multi-output DC-DC converter provided by the present invention;

Fig. 6 is a schematic circuit diagram corresponding to yet another embodiment of the multi-output DC-DC converter in Fig. 3;

FIG. 7 is a circuit schematic diagram of one embodiment of the isolated feedback control circuit of FIG. 6 .

detailed description

The following descriptions of various embodiments refer to the accompanying drawings to illustrate specific embodiments in which the present invention can be implemented. The directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", etc., are for reference only The orientation of the attached schema. Therefore, the directional terms used are used to illustrate and understand the present invention, but not to limit the present invention.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 3 , it is a schematic block diagram of an embodiment of the multi-output DC-DC converter provided by the present invention, combined with the circuit schematic diagram in FIG. 4 . In this embodiment, the multi-output DC-DC converter is used for powering the wireless radio frequency unit, including:

The primary conversion circuit A is connected to a DC input power supply Vin, which may be a unidirectional power conversion circuit with a voltage stabilizing function;

At least two secondary conversion circuits, wherein the first secondary conversion circuit B is used to output the converted first DC power supply (Vout1) to the power amplifier circuit connected to it, and the second secondary conversion circuit C is used to convert The second DC power supply (Vout2) obtained after conversion is output to the digital circuit connected thereto;

The transformer T has a primary winding and at least two secondary windings, the primary winding is connected to the primary conversion circuit A, and the first secondary conversion circuit B and the second secondary conversion circuit C are respectively connected to a secondary winding;

Among them, the primary conversion circuit A and at least two secondary conversion circuits (B, C) are coupled through a transformer T, and at least two secondary conversion circuits (B, C) are coupled to each other through a transformer T, thereby realizing Energy is transferred from the primary side conversion circuit A to at least two secondary side conversion circuits (B, C), and energy is transferred between the two secondary side conversion circuits (B, C);

The primary-side conversion circuit A at least includes a step-down stabilized voltage conversion circuit and a DC/AC conversion circuit connected to each other, wherein the buck-type stabilized voltage conversion circuit includes at least a first switch tube Q1 and a second switch tube Q2, and by adjusting The duty cycle of the first switching tube Q1 and the second switching tube Q2 can adjust the voltage of the first DC power supply and the second DC power supply, that is, the duty cycle of the first switching tube Q1 can be adjusted between 0-100%. regulation to vary the output voltage.

Specifically, please refer to the schematic diagram in FIG. 4, wherein the primary-side conversion circuit A includes a step-down circuit composed of a filter capacitor Ca, a first switch tube Q1, a second switch tube Q2, a first inductor L1, and a first capacitor C1. type voltage stabilizing conversion circuit, and a DC/AC conversion circuit composed of the third switching tube Q3, the fourth switching tube Q4 and the primary winding of the transformer T;

Wherein, the filter capacitor Ca is connected in parallel with the DC input power supply, its anode is connected to the drain of the first switching tube Q1, the source of the first switching tube Q1 is connected to one end of the first inductor L1, and the drain of the second switching tube Q2, The other end of the first inductor L1 is connected to the positive pole of the first capacitor C1 and the center tap of the primary winding of the transformer T, the source of the second switching transistor Q2, the negative pole of the first capacitor C1, the source of the third switching transistor Q3, The source of the fourth switching transistor Q4 is connected to the negative electrode of the filter capacitor Ca, and the drains of the third switching transistor Q3 and the fourth switching transistor Q4 are respectively connected to one end of the primary winding of the transformer T.

It can be understood that, in other embodiments, the primary-side conversion circuit A may also adopt a boost conversion circuit, for example.

Specifically, the first secondary conversion circuit B includes a fifth switching tube Q5, a sixth switching tube Q6, and a second capacitor C2;

Wherein, the anode of the second capacitor C2 is connected to the center tap of the first secondary winding of the transformer T, the source of the fifth switching transistor Q5 and the source of the sixth switching transistor Q6 are connected to the negative electrode of the second capacitor C2, and the fifth switching transistor Q5 The drain of the sixth switch tube Q6 and the drain of the sixth switch tube Q6 are respectively connected to one end of the first secondary winding of the transformer T, and both ends of the second capacitor C2 are connected to the power amplifier circuit.

Specifically, the second secondary conversion circuit C includes a seventh switching tube Q7, an eighth switching tube Q8, and a third capacitor C3;

Wherein, the anode of the third capacitor C3 is connected to the center tap of the second secondary winding of the transformer T, the source of the seventh switch Q7 and the source of the eighth switch Q8 are connected to the negative of the third capacitor C3, and the seventh switch Q7 The drain of the third capacitor C3 and the drain of the eighth switching tube Q8 are respectively connected to one end of the second secondary winding of the transformer T, and both ends of the third capacitor C3 are connected to the digital circuit.

It can be understood that, in the above schematic circuit diagram, the first switching tube Q1 and the second switching tube Q2 have complementary duty cycles, for example, when the duty cycle of the first switching tube Q1 is d, the second switching tube The duty ratio of Q2 is 1-d; the duty ratios of the third switching tube Q3 and the fourth switching tube Q4 are both 50%, that is, when the third switching tube Q3 is turned on, the fourth switching tube Q4 is turned off, and the fourth switching tube Q4 is turned on The third switching tube Q3 is turned off; the third switching tube Q3 is switched on and off synchronously with the fifth switching tube Q5 and the seventh switching tube Q7, and the fourth switching tube Q4 is switched on and off synchronously with the sixth switching tube Q6 and the eighth switching tube Q8.

Wherein, the third capacitor C3 is a large-capacity low-voltage capacitor, and the second capacitor C2 and the fourth capacitor C4 are high-voltage aluminum electrolytic capacitors.

It can be understood that the first secondary conversion circuit B and the second secondary conversion circuit C constitute a multifunctional power conversion circuit, which can realize at least two functions, wherein: the first function is to realize the AC/DC rectification function , that is, the AC energy transmitted from the primary side of the transformer T passes through the fifth switch tube Q5 and the sixth switch tube Q6 in the first secondary side conversion circuit B, and the seventh switch tube Q7 in the second secondary side conversion circuit C and the eighth switching tube Q8 rectify to become a direct current, which is respectively supplied to the power amplifier circuit and the digital circuit.

The second function is to realize the bidirectional transfer of energy between the first secondary conversion circuit B and the second secondary conversion circuit C. Among them, two-way transmission includes 3 modes:

Mode 1: When the fifth switching tube Q5 and the seventh switching tube Q7 switch synchronously, and the sixth switching tube Q6 and the eighth switching tube Q8 switch synchronously, because the winding connected to the first secondary conversion circuit B and the second secondary Coupling between the windings connected to the side conversion circuit C, energy can be freely transferred in two directions between the first secondary side conversion circuit B and the second secondary side conversion circuit C;

Mode 2: when the fifth switching tube Q5 and the sixth switching tube Q6 are turned off, energy can only flow from the second secondary side conversion circuit C to the first secondary side conversion circuit B;

Mode 3: when the seventh switching tube Q7 and the eighth switching tube Q8 are turned off, energy can only flow from the first secondary side conversion circuit B to the second secondary side conversion circuit C.

In addition, by adjusting the duty cycle of the first switch tube Q1 and the second switch tube Q2, the voltages of the first DC power supply and the second DC power supply can be adjusted. Specifically, the duty cycle of the first switch tube Q1 can be 0 Adjust between -100% to vary the output voltage. The principle is as follows: By changing the duty ratio d of the first switch tube Q1, the voltage at point a (that is, the positive pole of the first capacitor C1) can be adjusted. The relationship between the voltage at point a and the input voltage Vin is: Va=Vin*d ; In addition, since the energy between the first secondary conversion circuit B and the second secondary conversion circuit C can flow bidirectionally, the output voltage of the second secondary conversion circuit C and the output voltage of the first secondary conversion circuit B remain constant When adjusting the voltage output by the first secondary conversion circuit B, the voltage output by the second secondary conversion circuit C will also change accordingly; the voltages of the three points a, b, and c in Figure 4 The proportional relationship is determined by the turns ratio of the primary and secondary windings of the transformer T, assuming that the winding turns of the transformers connected to the three parts of the primary conversion circuit A, the first secondary conversion circuit B and the second conversion circuit C are respectively Na, Nb and Nc, then the relationship between the voltage ratio of the three points a, b, c and the number of turns of the three sets of windings is: Va: Vb: Vc=Na: Nb: Nc.

As shown in Figure 5, it is a schematic diagram of the first secondary side conversion circuit in another embodiment of the multi-output DC-DC converter provided by the present invention; the first secondary side conversion circuit B includes a ninth switch A full-bridge circuit composed of tube Q9, tenth switch tube Q10, eleventh switch tube Q11, and twelfth switch tube Q12;

Wherein, the first end of the first secondary winding of the transformer T is connected to the source of the ninth switching transistor Q9 and the drain of the eleventh switching transistor Q11, and the second end of the first secondary winding of the transformer T is connected to the tenth switching transistor Q10 The source of the twelfth switching tube Q12, the drain of the ninth switching tube Q9, the drain of the tenth switching tube Q10 are connected to the anode of the fourth capacitor C4, the source of the eleventh switching tube Q11, The source of the twelfth switching transistor Q12 is connected to the negative electrode of the fourth capacitor C4.

As shown in Figure 6, it is a schematic circuit diagram corresponding to another embodiment of the multi-channel output DC-DC converter in Figure 3; in this embodiment, an isolated feedback control circuit is further included, which is arranged at b between the point and the first switching tube Q1, that is, one end thereof is connected to the anode of the second capacitor C2, and is used to transmit a corresponding pulse width modulation signal to the gate of the first switching tube Q1; it can be understood that, for the circuit of FIG. 5, One end of the isolated feedback control circuit is connected to the positive pole of the fourth capacitor C4, that is, the voltage stabilization function is realized by detecting the voltage at point b; in addition, in other embodiments, the feedback control circuit can also be set to be connected to point a and the first Between a switch tube Q1, that is, one end thereof is connected to the anode of the first capacitor C1. In this way, the voltage stabilizing function is realized by detecting the voltage at point a.

As shown in FIG. 7, it is a schematic circuit diagram of an embodiment of the isolated feedback control circuit. In this embodiment, the isolated feedback control circuit further includes:

The sampling voltage comparison amplifier circuit is used to divide the voltage sampled from the positive pole of the second capacitor C2 or the positive pole of the fourth capacitor C4 (the sampling voltage V_b from point b is shown in the figure) and compare it with a reference voltage , and amplified, specifically including: voltage divider resistors R1 and R2, third resistor R3, fifth capacitor C5, and first comparator OP1; wherein the sampling voltage V_b is divided by voltage divider resistors R1 and R2, and compared with the reference The voltage Vref is compared and amplified by OP1, R3, and C5;

The pulse width modulation circuit is used to compare the amplified signal from the sampling voltage comparison amplifier circuit with a predetermined sawtooth signal, and generate a pulse width modulation signal, specifically including: a sawtooth signal source V_SAW and a second comparator OP2, Among them, the signal amplified by the sampling voltage comparison amplifier circuit is compared with V_SAW, and the second comparator OP2 generates a pulse width modulation (PWM) signal;

The isolation circuit includes at least an optocoupler for transmitting the pulse width modulation signal generated by the pulse width modulation circuit to the gate of the first switching transistor Q1. Specifically, the isolation circuit includes an optocoupler OPT1, a fourth resistor R4 and a second Five resistors.

Correspondingly, the embodiment of the present invention also provides a wireless radio frequency unit (Radio Remote Unit, RRU), which uses the aforementioned multi-output DC-DC converter shown in Figure 3 and Figure 7, wherein the multi-output DC-DC converter One output of the DC conversion is connected to the power amplifier circuit, and the other output is connected to the digital circuit. For more details, please refer to the foregoing description of FIGS. 3-7 , which will not be repeated here.

Implementing the embodiment of the present invention has the following beneficial effects:

First of all, implementing the embodiment of the present invention can realize multiple output power supplies through a simple circuit structure, at least one of which can be connected to a power amplifier circuit, and the other can be connected to a digital circuit;

In addition, by adjusting the duty ratio of the first switching tube Q1 in the primary conversion circuit A, the voltage output from the first secondary conversion circuit B and the voltage output from the second secondary conversion circuit C can be adjusted and Stablize;

Moreover, since bidirectional flow of energy can be realized between the first secondary conversion circuit B and the second secondary conversion circuit C, the voltage output from the second secondary conversion circuit C and the voltage output from the first secondary conversion circuit B Maintaining a fixed proportional voltage regulator, so that when the voltage output by the first secondary conversion circuit B is adjusted, the voltage output by the second secondary conversion circuit C can follow the change;

Furthermore, since energy can flow bidirectionally between the first secondary conversion circuit B and the second secondary conversion circuit C, the large-capacity filter capacitors of the first secondary conversion circuit B and the second secondary conversion circuit C can realize Shared, thereby reducing the total number of capacitors and reducing costs; and by configuring the third capacitor C3 as a large-capacity low-voltage capacitor (such as a tantalum capacitor) in the second secondary side conversion circuit C, thereby reducing or canceling the high-voltage aluminum in the high-voltage power amplifier circuit The number of electrolytic capacitors (second capacitor C2) improves system reliability and life;

Since bidirectional flow of energy can be realized between the first secondary conversion circuit B and the second secondary conversion circuit C, the dynamic response performance of the first secondary conversion circuit B can be further improved, and the voltage of the second secondary conversion circuit C can be extended keep time. When the output port of the first secondary conversion circuit B has a dynamic voltage drop, the energy at the output port of the second secondary conversion circuit C can flow into the B port through the winding of the seventh switching tube Q7, the eighth switching tube Q8 and the transformer T, reducing Voltage drop; when there is a dynamic voltage overshoot at the output port of the first secondary conversion circuit B, the energy at the output port of the first secondary conversion circuit B can flow in through the fifth switching tube Q5, the sixth switching tube Q6 and the winding of the transformer T The output port of the second secondary conversion circuit C reduces voltage overshoot; and when the input voltage Vin is powered off, it is often hoped that the voltage at the output port of the second secondary conversion circuit C can be maintained for a little longer to prolong the working time of the digital circuit , at this time, both the first switch tube Q1 and the second switch tube Q2 are turned off, the fifth switch tube Q5 and the sixth switch tube Q6 continue to work, so that the energy of the output port of the first secondary side conversion circuit B flows to the second secondary side The output port of the side conversion circuit C, thereby prolonging the voltage holding time of the second secondary side conversion circuit C.

The above disclosure is only a preferred embodiment of the present invention, which certainly cannot limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims (6)

1. A multi-channel output DC-DC converter for powering a wireless radio frequency unit, characterized in that it comprises: The primary conversion circuit is connected with a DC input power supply; At least two secondary conversion circuits, wherein the first secondary conversion circuit is used for rectification and conversion, and the first DC power obtained after conversion is output to the power amplifier circuit connected to it, and the second secondary conversion circuit is used for rectification transforming, and outputting the transformed second DC power supply to a digital circuit connected thereto; The transformer has a primary winding and at least two secondary windings, the primary winding is connected to the primary conversion circuit, and the first secondary conversion circuit and the second secondary conversion circuit are respectively connected to a secondary A winding, wherein the first secondary conversion circuit includes a fifth switching tube, a sixth switching tube and a second capacitor; Wherein, the primary conversion circuit and the at least two secondary conversion circuits are coupled through a transformer, and the at least two secondary conversion circuits are coupled to each other through a transformer, so that the energy in the two secondary conversion circuits transfer between each other; The primary conversion circuit includes at least a first switch tube and a second switch tube, and the first DC power supply and the second switch tube can be adjusted by adjusting the duty ratio of the first switch tube and the second switch tube. 2. The voltage of the DC power supply; Wherein, the primary-side conversion circuit includes a step-down voltage stabilizing conversion circuit composed of a filter capacitor, a first switch tube, a second switch tube, a first inductor and a first capacitor, and a third switch tube, a fourth switch tube A DC/AC conversion circuit composed of a tube and the primary winding of the transformer; Wherein, the filter capacitor is connected in parallel with the DC input power supply, its anode is connected to the drain of the first switch tube, and the source of the first switch tube is connected to one end of the first inductor and the drain of the second switch tube, so The other end of the first inductance is connected to the positive pole of the first capacitor and the middle tap of the primary winding of the transformer, the source of the second switching tube, the negative pole of the first capacitor, the source of the third switching tube, the fourth switch The source of the tube is connected to the negative pole of the filter capacitor, and the drain of the third switch tube and the drain of the fourth switch tube are respectively connected to one end of the primary winding of the transformer; Wherein, it further includes an isolated feedback control circuit, one end of which is connected to the positive pole of the fourth capacitor, and is used to transmit a corresponding pulse width modulation signal to the gate of the first switching tube, and the isolated feedback control circuit further includes: A sampling voltage comparison amplifier circuit, configured to divide the voltage sampled from the positive electrode of the second capacitor and then compare it with a reference voltage and amplify it; A pulse width modulation circuit, used to compare the amplified signal from the sampling voltage comparison amplifier circuit with a predetermined sawtooth wave signal, and generate a pulse width modulation signal; The isolation circuit at least includes an optocoupler, configured to transmit the pulse width modulation signal generated by the pulse width modulation circuit to the gate of the first switch tube; Wherein, the anode of the second capacitor is connected to the center tap of the first secondary winding of the transformer, the source of the fifth switching transistor and the source of the sixth switching transistor are connected to the negative electrode of the second capacitor, and the The drain of the fifth switch tube and the drain of the sixth switch tube are respectively connected to one end of the first secondary winding of the transformer, and both ends of the second capacitor are connected to a power amplifier circuit. 2. The multi-output DC-DC converter according to claim 1, wherein the second secondary conversion circuit comprises a seventh switching tube, an eighth switching tube and a third capacitor; Wherein, the anode of the third capacitor is connected to the center tap of the second secondary winding of the transformer, the source of the seventh switching transistor and the source of the eighth switching transistor are connected to the negative electrode of the third capacitor, and the The drain of the seventh switch tube and the drain of the eighth switch tube are respectively connected to one end of the second secondary winding of the transformer, and both ends of the third capacitor are connected to a digital circuit. 3. The multi-channel output DC-DC converter as claimed in claim 2, characterized in that, The first switch tube and the second switch tube have complementary duty ratios, the duty ratios of the third switch tube and the fourth switch tube are both 50%, and the third switch tube and the fourth switch tube have complementary duty cycles. The fifth switching tube and the seventh switching tube are switched synchronously, and the fourth switching tube is switched synchronously with the sixth switching tube and the eighth switching tube. 4. The multi-output DC-DC converter according to claim 2, wherein the first secondary side conversion circuit comprises a ninth switching tube, a tenth switching tube, an eleventh switching tube, a A full-bridge rectifier circuit composed of twelve switch tubes; Wherein, the first end of the first secondary winding of the transformer is connected to the source of the ninth switching transistor and the drain of the eleventh switching transistor, and the second end of the first secondary winding of the transformer is connected to the first The source of the eleventh switching tube and the drain of the twelfth switching tube, the drains of the ninth switching tube and the tenth switching tube are connected to the positive pole of the fourth capacitor, and the eleventh switching tube The source and the source of the twelfth switch tube are connected to the negative pole of the fourth capacitor. 5. The multi-output DC-DC converter according to claim 4, wherein the third capacitor is a large-capacity low-voltage capacitor, and the second capacitor and the fourth capacitor are high-voltage aluminum electrolytic capacitors. 6. A wireless radio frequency unit, comprising the multi-channel output DC-DC converter as claimed in any one of claims 1-5, one output of the multi-channel output DC-DC conversion is connected to a power amplifier circuit, and the other output Connect digital circuits.