Patent Publication Number: US-2023155619-A1

Title: Power mixer, radio frequency circuit, device and equipment

Description:
TECHNICAL FIELD 
     The invention relates to the technical field of electronics and communication, in particular a power mixer, radio frequency circuit, device and equipment. 
     BACKGROUND 
     The commonly used CMOS up-mixer in the prior art (as shown in  FIG.  1   ) includes six NMOS transistors (M 1 ˜M 6 ) and the baseband voltage signal is input from the gates of M 5  and M 6 . The baseband voltage signal is converted into a baseband current signal by the action of M 5  and M 6 , and is output by the drains of M 5  and M 6 . 
     M 1 ˜M 4  are switch tubes, the local oscillator signal is input from the gate of M 1 ˜M 4 , and the baseband current signal input by the drain of M 5  and M 6  is switched and transmitted to M 1 ˜M 4  according to the frequency of the local oscillator signal, so as to realize the frequency addition. The final radio frequency current signal is converted into a radio frequency voltage signal via the resistors R 1  and R 2  for being finally output. 
     Such CMOS up-mixer has several defects: in one aspect, since M 1 ˜M 4  work in the switching state, a relatively strong local oscillator signal is required, and the power consumption is relatively high. In another aspect, due to the low operating voltage of the CMOS process, the low current density, and the voltage drop across the resistors R 1  and R 2 , the output power is low. In the third aspect, in order to realize linear conversion, when M 5  and M 6  convert the baseband voltage signal into the baseband current signal, M 5  and M 6  must work in a fully conducting state. When the input voltage signal is relatively low, M 5  and M 6  will enter the cut-off state, and the linearity is poor. 
     SUMMARY 
     The technical problem mainly solved by the present invention is to provide a power mixer, radio frequency circuit, device, and equipment, which can improve the linearity and efficiency of baseband voltage signal conversion into baseband current model, save power consumption, and increase output power. 
     In order to achieve the above objective, the first technical solution adopted by the present invention is to provide a power mixer, characterized by comprising: a mixer module, which amplifies an analog baseband current signal by a silicon germanium heterojunction bipolar transistor amplifying circuit, and converts a local oscillator voltage signal into a local oscillator current signal by a silicon germanium heterojunction bipolar transistor switching circuit, wherein the silicon germanium heterojunction bipolar transistor switching circuit receives the amplified analog baseband current signal, and mixes the amplified analog baseband current signal and the local oscillator current signal into a radio frequency current signal; and a transformer module, which converts the radio frequency current signal into a radio frequency power signal and then outputs the radio frequency power signal from the power mixer. 
     In order to achieve the foregoing objective, the second technical solution adopted by the present invention is to provide a radio frequency circuit including the power mixer in the first technical solution. 
     In order to achieve the above object, the third technical solution adopted by the present invention is to provide a chip including the radio frequency circuit in the second technical solution. 
     In order to achieve the above objective, the fourth technical solution adopted by the present invention is to provide a wireless communication device including the chip in the third technical solution. 
     The beneficial effects of the present invention are: the present invention designs a power mixer, which combines a silicon germanium (SiGe) heterojunction (HBT) bipolar transistor amplifying circuit, a silicon germanium (SiGe) heterojunction (HBT) bipolar transistor switching circuit and a transformer circuit. The present application improves the linearity and efficiency of converting a baseband voltage signal into a baseband current model, saves power consumption, and improves output power. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a prior art CMOS up-mixer structure; 
         FIG.  2    is a schematic diagram of the structure of a power mixer of the present invention; and 
         FIG.  3    is a schematic diagram of the circuit structure of a mixer module of the present invention. 
     
    
    
     The symbols of the components in the drawings are as follows:  101 —capacitor one,  102 —first inductance,  103 —second inductance,  104 —third inductance,  105 —fourth inductance,  106 —capacitor two,  107 —capacitor three,  201 —capacitor four,  202 —resistance one,  203 —resistance two,  204 —triode one,  205 —resistor three,  206 —resistor four,  207 —triode two,  208 —resistor five,  209  —resistor six,  210 —triode three,  211 —resistance seven,  212 —resistance eight,  213 —triode four,  214 —resistance nine,  215 —triode five,  216 —triode six,  217 —triode seven,  218 —resistance ten,  219  —resistor eleven,  220 —resistance twelve,  221 —triode eight,  222 —resistance thirteen,  223 —resistance fourteen,  224  triode nine,  225 —resistance fifteen,  226 —resistance sixteen,  227 —triode ten,  228  resistor seventeen,  229 —resistance  18 ,  230 —capacitor five,  231 —capacitor six,  232 —resistance nineteen,  233 —resistance twenty,  234 —triode eleven,  235 —triode twelve,  236 —resistance twenty—one,  237 —resistance twenty—two,  238 —capacitor seven,  239 —capacitor eight,  240 —resistance twenty—three,  241 —resistance twenty—four,  242 —triode thirteen,  243 —triode fourteen,  244 —resistance twenty—five,  245 —resistance twenty—six,  246 —capacitor nine. 
     DESCRIPTION OF THE EMBODIMENTS 
     The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to make a clearer definition of the protection scope of the present invention. 
     It should be noted that the terms “first”, “second”, “third”, etc. in the claims and specification of this application are used to distinguish similar objects, and not necessarily used to describe a specific sequence or sequence. 
     The present invention adopts a silicon germanium (SiGe) heterojunction (HBT) triode process, and specifically provides a power mixer, which combines a silicon germanium (SiGe) heterojunction (HBT) bipolar transistor amplifying circuit, a silicon germanium (SiGe) heterojunction (HBT) bipolar transistor switching circuit and a transformer circuit. The present application not only utilizes the high gain characteristics of SiGe technology, but also combines the characteristics of bipolar transistors that can play a switching role in saturation and cut-off states. Using a bipolar transistor switch circuit to replace the traditional CMOS tube switch circuit can convert the local oscillator voltage signal into a vibration current signal, thereby reducing the power consumption of the local oscillator drive circuit. 
       FIG.  2    shows a specific embodiment of a power mixer structure of the present invention. In this embodiment, the power mixer of the present invention includes a mixer module and a transformer module. The mixer module mixes the baseband current signal and the local oscillator signal to generate a radio frequency current signal, and the transformer module receives the radio frequency current, converts it into a radio frequency power signal and output. 
     In an embodiment of the present invention, the analog baseband current signal BB 0  input by the analog baseband is input to the BBP_IN of a I-path mixer module circuit. BB 90  is input to the BBP_IN of a Q-path mixer module circuit, BB 180  is input to the BBN_IN of the I-path mixer module circuit, and BB 270  is input to the BBN_IN of the Q-path mixer module circuit. The structure of the I-path mixer module circuit is the same as that of the Q-path mixer module circuit. I-path local oscillator voltage signal (LOIN- 0  or LOIN 180 ) and I-path baseband current signal (BB 0  or BB 180 ) are mixed to generate two paths of radio frequency current signals. One of the radio frequency current signals is input from the first radio frequency current signal output terminal to the common connection terminal between a first inductor  102  and the capacitor  101  (third capacitor) of the transformer module, another radio frequency current signal is input from the second radio frequency current signal output terminal to the common connection terminal between the second inductor  103  and the capacitor  101  (third capacitor) of the transformer module. 
     The Q-path local oscillator voltage signal (LOIN- 90  or LOIN 270 ) and the Q-path baseband current signal (BB 90  or BB 270 ) are mixed to generate two radio frequency current signals. One of the radio frequency current signals is input from the first radio frequency current signal output terminal to the common connection terminal between the first inductor  102  and the capacitor  101  (third capacitor) of the transformer module. The other radio frequency current signal is input from the second radio frequency current signal output terminal to the common connection terminal between the second inductor  103  and the capacitor  101  (third capacitor) of the transformer module. 
     In an embodiment of the present invention, the radio frequency current signal input circuit of the transformer module is composed of a first inductor  102 , a second inductor  103  and a capacitor  101  (third capacitor). The first inductor  102  and the second inductor  103  are connected in series, and the other terminal of the first inductor  102  is connected to one pole of the capacitor  101  (third capacitor), a radio frequency current signal receiving terminal is formed between the first inductor  102  and the second inductor  103  and is connected to the first radio frequency current signal output terminal in the mixer module. The other terminal of the second inductor  103  is connected to the other pole of the capacitor  101  (third capacitor), and another radio frequency current signal receiving terminal is formed between the second inductor  103  and the capacitor  101 , the radio frequency current signal receiving terminal is connected to the second radio frequency current signal output terminal in the mixer module. 
     The radio frequency power signal output circuit of the transformer module is composed of a third inductor  104 , a fourth inductor  105 , a second capacitor  106  (a fourth capacitor) and a third capacitor  107  (a fifth capacitor). The third inductor  104  and the fourth inductor  105  are connected in series, the other terminal of the third inductor  104  is connected to one pole of the capacitor two  106  and the one pole of the capacitor three  107 , and the other terminal of the fourth inductor  105  is connected to the other pole of the capacitor two  106  and connected to the ground, the other pole of the capacitor three  107  is connected to the output terminal of the radio frequency power signal. 
     In this transformer module, the first inductor  102  and the third inductor  104  have mutual inductance, and the mutual inductance coefficient is K1, the second inductor  103  and the fourth inductor  105  have mutual inductance, and the mutual inductance coefficient is K2, and the turns ratio of the transformer is 1:1. When the transformer is outputting at low power, the post-stage power amplifier can be omitted (for example, the output power is about 10 dBm). When the output power of the transformer increases to about 20 dBm, it can act as the first gain stage of the power amplifier, thereby simplifying the system and saving power consumption. 
       FIG.  3    shows a specific embodiment of the circuit structure of a mixer module of the present invention. In this embodiment, the power mixer module circuit of the present invention includes a silicon germanium heterojunction bipolar transistor amplifying circuit and a silicon germanium heterojunction bipolar transistor switching circuit. The silicon germanium heterojunction bipolar transistor amplifying circuit amplifies the analog baseband current signal input by the analog baseband, and the amplified analog baseband current signal is input to the silicon germanium heterojunction bipolar transistor switching circuit. The silicon germanium heterojunction bipolar transistor switch circuit converts the local oscillator voltage signal into the local oscillator current signal, the silicon germanium heterojunction bipolar transistor switch circuit receives the amplified analog baseband current signal and mixes it with the local oscillator current signal to obtain the radio frequency current signal. 
     In an embodiment of the present invention, the silicon germanium heterojunction bipolar transistor amplifying circuit is composed of two identical units, and the two units respectively process the I-path baseband current signal and the Q-path baseband current signal. Each unit includes nine silicon germanium heterojunction bipolar transistors, seventeen bias resistors, and one capacitor (capacitor four  201  or capacitor five  230 ). 
     The following takes the I-path baseband current signal amplifying circuit as an example to illustrate its specific structure: 
     The I-path baseband current signal amplifying circuit includes eight parallel units, and each unit is composed of a silicon germanium heterojunction bipolar transistor and two series-connected upper bias resistors (a first resistor and a second resistor). One terminal of a bias resistor (the first resistor) is connected to the base of the silicon germanium heterojunction bipolar transistor, and one terminal of the other bias resistor (the second resistor) is connected to a bias voltage input terminal. A bias voltage is provided for the bias circuit to adjust the magnitude of the output current signal of the collector of the silicon germanium heterojunction bipolar transistor. A connection point is set between the two bias resistors, and one pole of the capacitor four  201  is connected through the connection point. Furthermore, the other pole of the capacitor four  201  is connected to the input terminal of the I-path analog baseband current signal. The I-path baseband current signal is input through the input terminal of the analog baseband current signal. The emitter of the silicon germanium heterojunction bipolar transistor is connected to the collector of the ninth silicon germanium heterojunction bipolar transistor. 
     As shown in  FIG.  3   , in the eight parallel units, resistor one  202 , resistor two  203 , triode one  204  constitute a unit, resistor three  205 , resistor four  206 , triode two  207  constitute a unit, resistor five  208 , resistor six  209 , triode three  210  constitutes a unit. Resistor seven  211 , resistor eight  212 , and triode four  213  constitute a unit, and there are four units that are not shown in detail. A connection point between resistor one  202  and resistor two  203 , a connection point between resistor three  205  and resistor four  206 , a connection point between resistor five  208  and resistor six  209 , a connection point between resistor seven  211  and resistor eight  212  point, and a connection point between the remaining four cells and the two bias resistors are connected to each other and connected one pole of the capacitor four  201 . Therefore, the other pole of the capacitor four  201  is connected to the input terminal BBP_IN of the I-path analog baseband current signal. The triode collectors of the eight units are connected to each other and are connected to two baseband current signal output lines so as to communicate with the silicon germanium heterojunction bipolar transistor switching circuit. The two output lines are respectively connected to the emitter of the triode eleven  234  and the emitter of the triode twelve  235 . The triode emitters of the eight units are interconnected and connected to the collector of the ninth triode (triode five  215 ). The base of the triode five  215  is connected to a bias resistor (the third resistor or the resistor nine  214 ), and the other terminal of the resistor nine  214  is connected to a bias voltage input terminal, and the bias voltage input terminal provides the triode five  215  with a bias voltage VB. The emitter of triode five  215  is grounded. 
     The structure of the Q-path baseband current signal amplifying circuit is the same as that of the I-path baseband current signal amplifying circuit, wherein the connection points between the eight bias resistors are connected to each other and are connected to one pole of the capacitor five  230 , and then pass through the other pole of the capacitor five  230  connect to the input terminal BBN_IN of the Q path analog baseband current signal. The triode collectors of the eight units are connected to each other and are connected to two baseband current signal output lines so as to communicate with the silicon germanium heterojunction bipolar transistor switching circuit. The two output lines are respectively connected to the emitter of the triode thirteen  242  and the emitter of the triode fourteen  243 . The triode emitters of the eight units are interconnected and connected to the collector of the ninth triode (triode seven  217 ). The base of the triode seven  217  is connected to a bias resistor (resistor ten  218 ), and the other terminal of the resistor ten  218  is connected to a bias voltage input terminal, and the bias voltage input terminal provides the triode seven  217  with a bias voltage VB. The emitter of triode seven  217  is grounded. 
     The gain stage of the mixer module consists of eight side-by-side silicon germanium heterojunction bipolar transistors in the Q-path baseband current signal amplifying circuit and eight side-by-side silicon germanium heterojunctions in the I-path baseband current signal amplifying circuit. The area of the emitter region of the silicon germanium heterojunction bipolar transistor is incremented by binary. The current magnification can be switched by changing the number of the sixteen silicon germanium heterojunction bipolar transistors that are turned on. The bias voltages input by the sixteen silicon germanium heterojunction bipolar transistor bias circuits can be set individually or in any combination, so as to adjust the amplification factor of the baseband current signal according to the needs of practical applications. 
     In one embodiment of the present invention, the silicon germanium heterojunction bipolar transistor switching circuit consists of two cells with the same structure. Therein, a unit converts the I-path local oscillator voltage signal (LOIN- 0  or LOIN 180 ) into a local oscillator current signal, and mixes the amplified baseband current signal of path I with the I-path local oscillator current signal and processes it into a radio frequency current signal. Another unit converts the Q-path local oscillator voltage signal (LOIN- 90  or LOIN 270 ) into a local oscillator current signal, and mixes the amplified Q-path baseband current signal with the Q-path local oscillator current signal into a radio frequency current signal. 
     Each switch circuit unit includes two silicon germanium heterojunction bipolar transistors, four bias resistors and two capacitors. 
     The following takes the I signal switch circuit as an example to illustrate its specific structure: 
     The I-path signal switch circuit includes two silicon germanium heterojunction bipolar transistors (triode eleven  234  and triode twelve  235 ) arranged in parallel. The base terminal of each silicon germanium heterojunction bipolar transistor (triode eleven  234  or triode twelve  235 ) is connected in series with a fourth resistor (resistor twenty  233  or resistor twenty one  236 ) and a fifth resistor (resistor ten Nine  232  or resistor twenty-two  237 ), the other terminal of the fifth resistor (resistor nineteen  232  or resistor twenty-two  237 ) is connected to a bias voltage input terminal to input the bias voltage VBLO. A connection point is set between the fourth resistor and the fifth resistor, the connection point is connected to one pole of the second capacitor (capacitor six  231  or capacitor seven  238 ), and the other pole of the second capacitor is connected to the local oscillator voltage signal input terminal, the two local oscillator voltage signal input terminals are respectively connected to the I-path local oscillator voltage signal with a phase difference of 180°. For example, capacitor six  231  is connected to VLO-P at 0° and capacitor seven is connected to VLO-N at 180°. 
     The emitter terminals of the two SiGe heterojunction bipolar transistors are respectively connected to the SiGe heterojunction bipolar transistor amplifying circuit to receive the amplified analog baseband current signal. The collector terminals of the two silicon germanium heterojunction bipolar transistors are respectively connected to the first radio frequency current signal output terminal and the second radio frequency current signal output terminal. 
     As shown in  FIG.  3   , the base of a silicon germanium heterojunction bipolar transistor (triode eleven  234 ) is connected in series with two bias resistors (resistor nineteen  232  and resistor twenty  233 ), the other terminal of the resistor nineteen  232  (the fifth resistor) is connected to the local oscillator bias voltage input terminal to input the bias voltage VBLO. A connection point is set between resistor nineteen  232  (fifth resistor) and resistor twenty  233  (fourth resistor), this connection point is connected to one pole of capacitor six  231  (second capacitor), and the other pole of capacitor six  231  is connected the input terminal of the local oscillator voltage signal of path I, so that the 0° local oscillator voltage signal VLO-P is input to the input terminal. The collector of the triode eleven  234  is connected to the first radio frequency current signal output terminal, so that the radio frequency current signal formed by mixing the I-path local oscillator current signal and the I-path baseband current signal is input to the transformer module. The emitter of the triode eleven  234  is connected to the baseband current signal output line of the I-path baseband current signal amplifying circuit. 
     The base of another silicon germanium heterojunction bipolar transistor (triode twelve  235 ) is connected in series with two bias resistors (resistor twenty one  236  and resistor twenty two  237 ), and resistor twenty two  237  (fifth resistor), the other terminal is connected to the local oscillator bias voltage input terminal to input the bias voltage VBLO. A connection point is set between resistor twenty two  237  (fifth resistor) and resistor twenty one  236  (fourth resistor). This connection point is connected to one pole of capacitor seven  238  (second capacitor) and the other pole of capacitor seven  238  is connected to the input terminal of the 180° I local oscillator voltage signal, so that the input terminal inputs the I local oscillator voltage signal VLO-N. The collector of the triode twelve  235  is connected to the second radio frequency current signal output terminal, so that the radio frequency current signal formed by mixing the I-path local oscillator current signal and the I-path baseband current signal is input into the transformer module. The emitter of the triode twelve  235  is connected to the baseband current signal output circuit of the I-path baseband current signal amplifying circuit. 
     The structure of the Q-path signal switch circuit is the same as the above I-path signal switch circuit. 
     As shown in  FIG.  3   , the base of a silicon germanium heterojunction bipolar transistor (triode fourteen  243 ) is connected in series with two bias resistors (resistance twenty-five  244  and resistor twenty-six  245 ), and the other terminal of the resistor twenty-six  245  (fifth resistor) is connected to the local oscillator bias voltage input terminal to input the bias voltage VBLO. A connection point is set between resistor twenty-six  245  (fifth resistor) and resistor twenty-five  244  (fourth resistor). This connection point is connected to one pole of capacitor nine  246  (second capacitor) and the other pole of capacitor nine  246  is connected to the input terminal of the Q-path local oscillator voltage signal, so that the 90° Q-path local oscillator voltage signal VLO-P is input from the input terminal. The collector of the triode fourteen  243  is connected to the second radio frequency current signal output terminal, so that the radio frequency current signal formed by mixing the Q-path local oscillator current signal and the Q-path baseband current signal is input into the transformer module. The emitter of the triode fourteen  243  is connected to the baseband current signal output circuit of the Q-path baseband current signal amplifying circuit. 
     The base of another silicon germanium heterojunction bipolar transistor (triode thirteen  242 ) is connected in series with two bias resistors (resistor twenty-four  241  and resistor twenty-three  240 ), and the other terminal of resistor twenty-three  240  (fifth resistor) is connected to the local oscillator bias voltage input terminal to input the bias voltage VBLO. A connection point is set between resistor twenty-three  240  (fifth resistor) and resistor twenty-four  241  (fourth resistor). This connection point is connected to one pole of capacitor eight  239  (second capacitor) and the other pole of capacitor eight  239  is connected to the input terminal of the Q-path local oscillator voltage signal, so that a 270° Q-path local oscillator voltage signal VLO-N is input from the input terminal. The collector of the triode thirteen  242  is connected to the first radio frequency current signal output terminal, so that the radio frequency current signal formed by mixing the Q-path local oscillator current signal and the Q-path baseband current signal is input into the transformer module. The emitter of the triode thirteen  242  is connected to the baseband current signal output circuit of the Q-path baseband current signal amplifying circuit. 
     After using the silicon germanium heterojunction bipolar transistor switch circuit in the present invention, due to the effect of the bias circuit, compared with the strong local oscillator signal in the CMOS transistor circuit in  FIG.  1   , the present invention can reduce the intensity of the local oscillator signal to obtain the same mixing effect. 
     This type of power mixer can be used in radio frequency circuits, which can be used in low-power Bluetooth chip-level systems, and can also be used in other chips that need to include power mixer radio frequency circuits, and further used in Bluetooth products, wireless routers, mobile phones, mobile communication base stations and other wireless communication equipments. 
     The present invention combines a silicon germanium (SiGe) heterojunction (HBT) bipolar transistor amplifying circuit, a silicon germanium (SiGe) heterojunction (HBT) bipolar transistor switching circuit and a transformer circuit to design a power hybrid frequency converter, so as to improve the linearity and efficiency of baseband voltage signal conversion into baseband current model, save power consumption and increase output power. 
     The above are only the embodiments of the present invention, which do not limit the scope of the present invention. Any equivalent structural transformations made by using the contents of the description and drawings of the present invention, or directly or indirectly applied to other related technical fields, are the same. The theory is included in the scope of patent protection of the present invention.