Patent Publication Number: US-10326406-B2

Title: Amplifier device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwan application No. 105144234, which was filed on Dec. 30, 2016, and is included herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to an amplifier device; in particular, to an amplifier device capable of improving linearity. 
     BACKGROUND 
     With the prevalence of mobile devices nowadays, amplifier devices are used in communication modules in great quantity. Due to the fact that the power-gain curve and power-phase curve of an amplifier device tend to be non-linear when they reach a certain level, amplifier devices are limited in power usage. Though the approaches of reducing the power or introducing a pre-distortion circuit may be utilized, the complexity of circuit design and cost would increase correspondingly. Moreover, the linearity of an amplifier device varies according to the input signal, voltage source or temperature, so that if a pre-distortion circuit is utilized as previously described, different control factors need thus be considered, and the circuit design would also become more complicated. 
     Therefore, providing an amplifier device with simple circuit and capable of self-adjusting linearity becomes a critical issue. 
     SUMMARY 
     An amplifier device is provided in one of the embodiments of the present disclosure. The amplifier device includes an amplifying unit having a first end, a second end and a third end, in which the first end of the amplifying unit is configured for electrically connecting to a voltage source, the second end of the amplifying unit is configured for receiving an input signal, the first end of the amplifying unit is configured for outputting an output signal amplified by the amplifying unit, and the third end of the amplifying unit is configured for electrically connecting to a first reference potential; a bias module electrically connected to the second end of the amplifying unit for providing a bias voltage to the amplifying unit; and an impedance unit electrically connected to the bias module, in which an impedance value of the impedance unit is variable. The bias module adjusts a linearity of the amplifier device according to a frequency value of the input signal, a voltage value of the voltage source or a temperature value of the amplifier device, and the impedance value of the impedance unit is adjusted according to the frequency value of the input signal, the voltage value of the voltage source or the temperature value of the amplifier device. 
     An amplifier device is provided in one of the embodiments of the present disclosure. The amplifier device includes an amplifying unit having a first end, a second end and a third end, in which the first end of the amplifying unit is configured for electrically connecting to a voltage source, the second end of the amplifying unit is configured for receiving an input signal, the first end of the amplifying unit is configured for outputting an output signal amplified by the amplifying unit, and the third end of the amplifying unit is configured for electrically connecting to a first reference potential; a bias module electrically connected to the second end of the amplifying unit for providing a bias voltage to the amplifying unit; and an impedance unit electrically connected to the bias module, in which an impedance value of the impedance unit is variable. A voltage value of the voltage source is variable, and the impedance value of the impedance unit is adjusted according to a frequency value of the input signal, the voltage value of the voltage source or a temperature value of the amplifier device. 
     An amplifier device is provided in one of the embodiments of the present disclosure. The amplifier device includes an amplifying unit having a first end, a second end and a third end, in which the first end of the amplifying unit is configured for electrically connecting to a voltage source, the second end of the amplifying unit is configured for receiving an input signal, the first end of the amplifying unit is configured for outputting an output signal amplified by the amplifying unit, and the third end of the amplifying unit is configured for electrically connecting to a first reference potential; a bias module electrically connected to the second end of the amplifying unit for providing a bias voltage to the amplifying unit; and an impedance unit electrically connected to the bias module, in which an impedance value of the impedance unit is variable. The bias module includes a power element and a first bias element. The power element has a first end, a second end and a third end, in which the first end of the power element is configured for electrically connecting to a bias voltage source, and the third end of the power element is connected to the second end of the amplifying unit. The first bias element has a first end and a second end, in which the first end of the bias element is configured for electrically connecting to a reference power module, the second end of the first bias element is electrically connected to the second end of the power element and is configured for providing a variable current to the second end of the power element. The impedance value of the impedance unit and the current value of the variable current are adjusted according to a power of the input signal, a power of the output signal or an operation mode of the amplifier device, to adjust a linearity of the amplifier device 
     In order to further the understanding regarding the present disclosure, the following embodiments are provided along with illustrations to facilitate the disclosure of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagram of an amplifier device according to an embodiment of the present disclosure; 
         FIG. 2  shows a diagram of a first adjusting module and a second adjusting module according to an embodiment of the present disclosure; 
         FIGS. 3A-3Y  show diagrams of an impedance unit implemented by different elements according to the embodiments of the present disclosure; 
         FIG. 4  shows a diagram of a power-gain curve of an amplifier device; 
         FIG. 5  shows a diagram of a power-phase curve of an amplifier device; and 
         FIG. 6  shows a diagram of an amplifier device according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The aforementioned illustrations and following detailed descriptions are exemplary for the purpose of further explaining the scope of the present disclosure. Other objectives and advantages related to the present disclosure will be illustrated in the subsequent descriptions and appended drawings. 
     Reference is made to  FIG. 1 ,  FIG. 2  and  FIGS. 3A-3Y , where  FIG. 1  shows a diagram of an amplifier device according to an embodiment of the present disclosure,  FIG. 2  shows a diagram of a first adjusting module and a second adjusting module according to an embodiment of the present disclosure, and  FIGS. 3A-3Y  show diagrams of an impedance unit implemented by different elements according to the embodiments of the present disclosure. 
     In the following description, for the sake of brevity, for elements with two ends in  FIG. 1  and  FIG. 2 , the upper end would be the first end and the lower end would be the second end if an element is placed vertically, and the left end would be the first end and the right end would be the second end if an element is placed horizontally. For elements with three or more ends in  FIG. 1  and  FIG. 2 , reference in the description would be made according to the end number as labeled in the figures. 
     The amplifier device  1  includes an amplifying unit  11  and a bias module  12 . The amplifying unit  11  includes a first end, a second end and a third end. The first end of the amplifying unit  11  connects to a voltage source Vsource, the second end of the amplifying unit  11  receives an input signal S1, the first end of the amplifying unit  11  is configured for outputting an output signal S2 amplified by the amplifying unit, the third end of the amplifying unit  11  connects to a first reference potential Vref1. In the present embodiment, the amplifying unit  11  may be a bipolar junction transistor (BJT), and the voltage source Vsource is provided by a battery, with the voltage value being variable, e.g., time-varying. The amplifier device  1  may be installed in a mobile device (not shown in the figures), and may use the battery of the mobile device to provide the voltage source Vsource. The amplifier device  1  may be, such as, a power amplifier or a low noise amplifier, and a power amplifier is taken as exemplary in the present embodiment. Moreover, the input signal S1 and the output signal S2 may be AC signal, such as radio frequency (RF) signal. 
     The bias module  12  includes a power element  121 , a reference power module  122 , a first bias element  123 , a second bias element  124  and a third bias element  125 . The power element  121  has a first end, a second end and a third end. The first end of the power element  121  electrically connects to a bias voltage source Vbias, the third end of the power element  121  connects to the second end of the amplifying unit  11 . The bias module  12  adjusts a linearity of the amplifier device  1  according to a frequency value of the input signal S1, a voltage value of the voltage source Vsource or a temperature value of the amplifier device  1 . In the present embodiment, the bias voltage source Vbias and the voltage source Vsource may or may not have the same potential, and is not limited to either circumstance by the present disclosure. 
     The first bias element  123  has a first end and a second end. The first end of the first bias element  123  electrically connects to the reference power module  122 , the second end of the first bias element  123  electrically connects to the second end of the power element  121 . The second bias element  124  has a first end and a second end, and the first end of the second bias element  124  electrically connects to the second end of the first bias element  123 . In the present embodiment, the reference power module  122  is a current source which provides a reference current to the first bias element  123  of the bias module  12 . In other embodiments the reference power module  122  may be a voltage source or power modules with other kinds of power supplying. 
     The third bias element  125  has a first end and a second end, the first end of the third bias element  125  electrically connects to the second end of the second bias element  124 , the second end of the third bias element  125  electrically connects to a second reference potential Vref2 or other reference potentials, and is not limited by the present disclosure. 
     In the present embodiment, the amplifier device  1  further includes a first default capacitor  13 , a second default capacitor  14 , an impedance unit  15  and a first adjusting module  16 , so as to adjust the linearity of the amplifier device  1 . 
     The first default capacitor  13  has a first end and a second end, and the first end of the first default capacitor  13  electrically connects to the bias module  12 . In the present embodiment, the first end of the first default capacitor  13  electrically connects to the second end of the power element  121 , the second end of the first bias element  123  and the first end of the second bias element  124 . The second end of the first default capacitor  13  connects to the impedance unit  15 . The first default capacitor  13  can be used to block DC (direct current) signal. 
     The second default capacitor  14  has a first end and a second end. The first end of the second default capacitor  14  connects to the first end of the first default capacitor  13 , and the second end of the second default capacitor  14  electrically connects to the second reference potential Vref2. The second default capacitor  14  can be used to block DC (direct current) signal. 
     In the present embodiment, the power element  121  may be, such as a bipolar junction transistor (BJT), the first element  123  is a resistor, and the second bias element  124  and the third bias element  125  are respectively a diode. In the present embodiment, the second bias element  124  and the third bias element  125  may be, but not limited to, a diode composed of a p-type semiconductor or an n-type semiconductor, e.g., a diode composed of bipolar junction transistor (BJT). In other embodiments, the second bias element  124  and the third bias element  125  may be other elements, or be replaced by equivalent circuit such as a metal-oxide-semiconductor field-effect transistor (MOSFET). 
     In the present embodiment, since the bias module  12 , the second default capacitor  14  and the impedance  15  are often disposed in the same vicinity in circuit design, the second default capacitor  14 , the impedance unit  15  and the third bias element  125  may be all electrically connected to the second reference potential Vref2 as a common reference potential. In the present embodiment, the first reference potential Vref1 and the second reference potential Vref2 may be, but are not limited to, a ground potential or other reference potentials. Moreover, in the present embodiment, the reference power module  122  may be a variable current source, a constant voltage source or a variable voltage source, and current value of a reference current provided by the variable current source or voltage value of a reference voltage provided the variable voltage source may be adjusted according to a frequency value of the input signal S1, the voltage value of the voltage source Vsource or a temperature value of the amplifier device  1 , so as to adjust the bias voltage provided by the bias module  12  to the amplifying unit  11 . Comparing to the amplifier device that only has the amplifying unit  11  and the bias module  12 , the second capacitor  14  can be used to change the impedance viewed from the second terminal of the power element  121  to the external, such as the impedance to the AC signal, and the first default capacitor  13  and the impedance unit  15  can be further used to dynamically adjust the impedance viewed from the second terminal of the power element  121  to the external of the power element  121 . 
     In the present embodiment, the impedance value of the impedance unit  15  is variable, and by serially connecting the impedance unit  15  with the first default capacitor  13 , the equivalent impedance resulted from the first default capacitor  13  and the impedance unit  15  can be adjusted. In the present embodiment, the impedance unit  15  may be a variable resistor, a variable capacitor, a variable inductor, a switch or other equivalent circuit or electronic device capable of adjusting impedance value, such as a varactor, or the combination of the above-mentioned elements. The impedance unit  15  further includes an impedance control end Tctrl, which may receive a control signal. In the present embodiment, the amplifier device  1  further includes a first adjusting module  16 , configured to provide a first adjusting signal (e.g., the first adjusting voltage Vcontrol1) to the control end Tctrl of the impedance unit  15 , for adjusting the impedance value of the impedance unit  15 . In other embodiments, the impedance value of the impedance unit  15  may be adjusted according to a frequency value of the input signal S1, the voltage value of the voltage source Vsource or the temperature value of the amplifier device  1 . 
     The first adjusting module  16  includes a first amplifier  160 , a first resistor  161 , a second resistor  162 , a third resistor  163  and a fourth resistor  164 . The first amplifier  160  has a first input end, a second input end and an output end. The first resistor  161  is connected between the first end of the first amplifier  160  and a third reference potential Vref3. The second resistor  162  connects the first input end of the first amplifier  160  and the voltage source Vsource. The third resistor  163  is connected between the second input end of the first amplifier  160  and the output end of the first amplifier  160 . The fourth resistor  164  is connected between the first reference voltage Vr1 and the second input end of the first amplifier  160 . In the present embodiment, the output end of the first amplifier  160  of the first adjusting module  16  outputs a first adjusting voltage Vcontrol1 to adjust the impedance value of the impedance unit  15 , i.e., the output end of the first amplifier  160  of the first adjusting module  16  electrically connects to the control end Tctrl of the impedance unit  15 . In the present embodiment, the third reference potential Vref3 is a ground potential, i.e., 0V. In other embodiments, the third reference voltage Vref3 may be other reference potentials. 
     In the present embodiment, the first adjusting module is a differential amplifier architecture, thus the first adjusting voltage Vcontrol1 may be calculated and obtained according to the voltage value of the voltage source, the first reference voltage Vr1, the third reference potential Vref3, the impedance value of the first resistor  161 , the impedance value of the second resistor  162 , the impedance value of the third resistor  163  and the impedance value of the fourth resistor  164 . In the present embodiment, the third reference potential Vref3 is 0V, and thus the first adjusting voltage Vcontrol1 may be represented by the following equation 1: 
     
       
         
           
             
               
                 
                   
                     Vcontrol 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   = 
                   
                     
                       
                         
                           R 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1 
                         
                         
                           
                             R 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             1 
                           
                           + 
                           
                             R 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             2 
                           
                         
                       
                       * 
                       
                         ( 
                         
                           1 
                           + 
                           
                             
                               R 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               3 
                             
                             
                               R 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               4 
                             
                           
                         
                         ) 
                       
                       * 
                       Vsource 
                     
                     - 
                     
                       
                         
                           R 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           3 
                         
                         
                           R 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           4 
                         
                       
                       * 
                       Vr 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       1 
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
               
             
           
         
       
     
     In the equation above, R1 is the impedance value of the first resistor  161 , R2 is the impedance value of the second resistor  162 , R3 is the impedance value of the third resistor  163  and R4 is the impedance value of the fourth resistor  164 . Vcontrol1 represents the first adjusting voltage and Vr1 represents the first reference voltage. 
     According to equation 1, if the impedance value of the first resistor  161  equals to the impedance value of the third resistor  163  and the impedance value of the second resistor  162  equals to the impedance value of the fourth resistor  164 , equation 1 may be simplified to equation 2: 
     
       
         
           
             
               
                 
                   
                     Vcontrol 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   = 
                   
                     
                       ( 
                       
                         Vsource 
                         - 
                         
                           Vr 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1 
                         
                       
                       ) 
                     
                     * 
                     
                       ( 
                       
                         
                           R 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1 
                         
                         
                           R 
                           ⁢ 
                           
                               
                           
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                           2 
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                 
               
             
           
         
       
     
     In the present embodiment, the first reference voltage Vr1 is a constant, with only the voltage value of the voltage source being variable, and the impedance values of each resistor are also constant, which means that the first adjusting voltage Vcontrol1 is a function value of the voltage source Vsource. In other embodiments, other kinds of circuit may be utilized for the design of the first adjusting voltage Vcontrol1, so long as the voltage source Vsource is the main variable of the first adjusting voltage Vcontrol1. 
     In the present embodiment, the impedance value of the impedance unit  15  is adjusted according the voltage value of the voltage source Vsource, which means, based on the voltage value of the voltage source Vsource, adjusting the equivalent impedance seen from the third end of the power element  121  to the internal of the power element  121 , and further adjusting the bias voltage provided by the bias module  12  to the amplifying unit  11 . In other embodiments, the impedance value of the impedance unit  15  may be adjusted according to the a frequency value of the input signal S1 or other parameters, so as to further adjust the bias voltage provided by the bias module  12  to the amplifying unit  11 . For example, a frequency-voltage conversion circuit may first be used to detect the frequency of an input signal, the frequency is then converted into a voltage value, and then the impedance value of the impedance unit  15  may be adjusted by using the voltage value. In other embodiments, the amplifier device  1  may include a temperature sensor (not shown in the figures) for detecting the temperature of the amplifier device  1 . The impedance value of the impedance unit  15  may be adjusted according to the temperature of the amplifier device  1 , so as to further adjust the bias voltage provided by the bias module  12  to the amplifying unit  11 . In summary, in the embodiments of the present disclosure, the equivalent impedance seen from the third end of the power element  121  to the internal of the power element  121  may be adjusted according to the voltage value of the voltage source Vsource, a frequency value of the input signal S1 and the temperature of the amplifier device  1 . 
     In the present embodiment, the first adjusting module  16 , based on the variation of the voltage source Vsource, adjusts the impedance value of the impedance unit  15 . Therefore, the impedance seen outwardly from the second end of the power element  121  of the bias module  12  may be adjusted, which effects the equivalent impedance seen from the third end of the power element  121  to the internal of the power element  121 , further adjusts the bias voltage provided bias module  12  to the amplifying unit, and effects the linearity of the power-gain curve or the power-phase curve of the amplifying unit  11 . 
     In the present embodiment, the impedance unit  15  may be that shown by the diagrams in  FIGS. 3A-3Y , and may be, but not limited to, designed by using different resistors, capacitors, inductors, variable resistors, variable capacitors, variable inductors, switch elements (e.g., transistors or diodes), or the combination thereof. 
     [Embodiment of Amplifier Device with Two Adjusting Modules] 
     In the present embodiment, the amplifier device  1  further includes a second adjusting module  17 . The second adjusting module  17  includes a second amplifier  170 , a fifth resistor  171 , a sixth resistor  172 , a seventh resistor  173  and an eighth resistor  174 . The second amplifier  170  has a first input end, a second input end and an output end. The fifth resistor  171  is connected between the first input end of the second amplifier  170  and a fourth reference potential Vref4. The sixth resistor  172  is connected between the first input end of the second amplifier  170  and the voltage source Vsource. The seventh resistor  173  is connected between the second input end of the second amplifier  170  and the output end of the second amplifier  170 . The eighth resistor is connected between a second reference voltage Vr2 and the second input end of the second amplifier  170 . 
     In the present embodiment, the varying interval of the voltage source Vsource is divided into two intervals, which means that the voltage source Vsource has a first voltage interval and a second voltage interval. When the voltage value of the voltage source Vsource is within the first voltage interval, the first adjusting module  16  provides a first adjusting voltage to adjust the impedance value of the impedance unit  15 , and when the voltage value of the voltage source Vsource is within the second voltage interval, the second adjusting module  17  provides a second adjusting signal (e.g., a second adjusting voltage) to adjust the impedance value of the impedance unit  15 . In the present embodiment, both the output end of the first amplifier  160  of the first adjusting module  16  and the output end of the second amplifier  170  of the second adjusting module  170  electrically connect to the control end Tctrl of the impedance unit  15 . In other embodiments, a user may set the first reference voltage Vr1 and the second reference voltage Vr2 for the setting of the first voltage interval and the second voltage interval. In the present embodiment, the first adjusting voltage Vcontrol1 and the second adjusting voltage Vcontrol2, as described in the previous paragraph, are both a function value of the voltage source Vsource. In other embodiments, other circuits may be utilized for the design of the first adjusting voltage Vcontrol1 and the second adjusting voltage Vcontrol2, so long as the voltage source Vsource is the main variable of the first adjusting voltage Vcontrol1 and the second adjusting voltage Vcontrol2, the designs thereof not being limited to the above description. 
     In the present embodiment, the third reference potential Vref3 and the fourth reference potential Vref4 may be, but not limited to, a ground potential or other reference potentials. 
     In other embodiments, the first adjusting voltage Vcontrol1 of the first adjusting module  16  may electrically connect to the first impedance control end Tctrl1 as shown in  FIG. 3S  or  FIG. 3T , the second adjusting voltage Vcontrol2 may electrically connect to the second impedance control and Tctrl2 as shown in  FIG. 3S  or  FIG. 3T . A designer, by different practical demands, and according to the resistor-capacitor combination as shown in  FIG. 3S  or  FIG. 3T , may select different resistances or capacitances to generate different equivalent impedances. 
     In other embodiments, the voltage-varying interval of the voltage source Vsource may be divided into more intervals, and the number of the adjusting modules should be increased accordingly to provide adjusting voltages. 
     Reference is made to  FIG. 4  and  FIG. 5 , where  FIG. 4  shows a diagram of a power-gain curve of an amplifier device and  FIG. 5  shows a diagram of a power-phase curve of an amplifier device. 
     The solid line as shown in  FIG. 4  is the power-gain curve of an uncompensated amplifier device. In general, when the power of an uncompensated amplifier device exceeds a predetermined value, the gain curve extends downwardly and nonlinearly as shown in  FIG. 4 . After that, if a pre-distortion circuit or other compensation circuit is introduced, it would be shown as the dotted line I and the dotted line II in  FIG. 4 , where the dotted line I represents the gain linear area being drawn to higher power after the amplifier device is bias compensated, and when under higher power, the gain curve extends downwardly. The dotted line II represents, after the amplifier device is bias compensated, the linear area of the adjusted gain curve being not only drawn further, but also extended upwardly according to practical demand. 
     The solid line as shown in  FIG. 5  is the power-phase curve of an amplifier device not being bias compensated. As shown in  FIG. 5 , when the power is lower, the power-phase curve extends linearly, when the power increases to a predetermined value however, the power-phase curve starts to extend downwardly, and distortion occurs at the output end of the amplifier device. The dotted line III and the dotted line IV in  FIG. 5  are the power-phase curve adjusted according to different demands of the amplifier device  1  according to an embodiment of the present disclosure. Therefore, a user may compensate the linearity of the amplifier device  1  according to different factors, so as to increase the linearity of the amplifier device  1  effectively. 
     Reference is made to  FIG. 6 , which shows a diagram of an amplifier device according to another embodiment of the present disclosure. In the present embodiment, the amplifier device  1  as shown in  FIG. 6  is similar to the amplifier device  1  as shown in  FIG. 1 , one of the differences is that the first bias element  123  of the amplifier device  1  of  FIG. 1  is replaced by a first bias element  127 . In the present embodiment, the first bias element  127  may be a variable resistor. The first bias element  127  has a third control end Tctrl3 electrically connected with the first adjusting module  16 . Furthermore, in the present embodiment, the voltage source Vsource may have a constant voltage value. 
     In the present embodiment, when the power of the input signal S1 and the output signal S2 are changed, or the operation mode of the amplifying unit  11  is adjusted between a high power operation mode and a low power operation mode, a variable current I b , which flows into the second end of the power element  121  of the bias module  12  through the first bias element  127  from the reference power module  122  would be changed. For example, when the operation mode of the amplifying unit  11  is adjusted from the high power operation mode to the low power operation mode, the variable current I b  would be decreased. In the meantime, the impedance value of the impedance unit  15  will be adjusted simultaneously in accordance with the corresponding linearity. Therefore, in the present embodiment, the linearity of the frequency-phase curve can be adjusted accordingly. That is to say, in the present embodiment, the variable current of the first bias element  127  and the impedance value of the impedance unit  15  are taken as the main factors of the first adjusted voltage Vcontrol1. 
     Therefore, in the present embodiment, the first adjusting module  16  can, according to the power of the input signal S1 and the output signal S2 or the operation mode of the amplifier device, output a first adjusting voltage Vcontrol1, and by adjusting the impedance value of the impedance unit  15  over the first control end Tctrl and the third control end Tctrl3, and by the variable current I b  flows through the first bias element  127 , the linearity of the amplifier device  1  can be adjusted. 
     In other embodiments such as shown in  FIG. 3Y , the impedance unit  15  includes a switch element. When the operation mode of the amplifying unit  11  is changed (e.g., the operation mode of the amplifying unit  11  is adjusted between a high power operation mode and a low power operation mode), the first adjusting module  16  can, according to the operation mode of the amplifier device, outputs the first adjusting voltage Vcontrol1 corresponding to the operation mode, by controlling the switch element of the impedance unit  15  to be connected or disconnected through the first control end Tctrl1 and the third control end Tctrl3, and the variable current I b  passing through the first bias element  127 , an impedance value matching the operation mode can be provided, which further improves the linearity of the amplifier device. 
     The amplifier devices as provided in some of the preset disclosure are capable of output adjustment for bias modules according to different linearity factors, and are capable of bias compensation for amplifier devices according to the voltage value of a voltage source, the frequency value of an input signal or a temperature value. The other amplifier devices as provided in some of the preset disclosure are capable of impedance adjustment according to a power of the input signal, a power of the output signal or a operation mode of the amplifying unit. Therefore, the linearity or the tendency of the power-gain curve or the power-phase curve of an amplifier device may be adjusted accordingly to meet with practical demands. 
     The descriptions illustrated supra set forth simply the preferred embodiments of the present disclosure; however, the characteristics of the present disclosure are by no means restricted thereto. All changes, alterations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the present disclosure delineated by the following claims.