Abstract:
The present invention provides a liquid crystal panel driving circuit including an operational amplifier and a flexible substrate. The operational amplifier outputs an output signal based on an image signal and a feedback signal corresponding to the output signal without a high frequency content. In the flexible substrate with an inductance, the output signal passes through to a liquid crystal display via the inductance. The operational amplifier may include an operational amplifier element and a negative feedback circuit. The operational amplifier element includes a non-inverting input terminal supplied with the image signal, an inverting input terminal supplied with the feedback signal and an output terminal outputting the output signal. The negative feedback circuit formed between the output terminal and the inverting input terminal.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a liquid crystal panel driving circuit. More particularly, the present invention relates to a liquid crystal panel driving circuit, in which a distortion of a wave form of an output or an oscillation of an operational amplifier for driving a liquid crystal panel that is caused by an influence of a self-inductance of a flexible substrate can be suppressed, when a flexible substrate is used as a medium through which a liquid crystal panel driving circuit and a liquid crystal panel are connected.  
           [0003]    2. Description of the Related Art  
           [0004]    A liquid crystal panel driving circuit is disposed at an input stage of a liquid crystal panel. This liquid crystal panel driving circuit has a plurality of operational amplifiers corresponding to the number of drive lines. A TFT type liquid crystal panel has transistors (TFTs) arrayed in a form of matrix. Each of the operational amplifiers of the liquid crystal panel driving circuit is connected to, for example, a source of this transistor by the first signal line. Then, the liquid crystal panel serving as a capacitance load is charged and discharged through this transistor. Incidentally, another second signal line is connected to a gate of the transistor. An on/off control of a predetermined transistor is carried out in accordance with an input signal through the second line.  
           [0005]    [0005]FIG. 8 is a view showing an arrangement of a conventional operational amplifier for a liquid crystal panel. As shown in FIG. 8, an operational amplifier  806   a  for a liquid crystal panel contains an operational amplifier element  806 . The operational amplifier element  806  has a non-inverting input terminal  801  to receive an input signal. An output terminal  802  of the operational amplifier element  806  is connected as a voltage follower to an inverting input terminal  803  so as to form a negative feedback circuit. Typically, the output terminal  802  of the operational amplifier element  806  is connected through a flexible substrate  804  to a liquid crystal panel  805  serving as a load.  
           [0006]    Here, the operation of the conventional liquid crystal panel driving circuit is described with reference to FIG. 9. FIG. 9 is a conceptual view of the conventional liquid crystal panel driving circuit. A liquid crystal panel driving circuit  906  shown in FIG. 9 is provided with: an operational amplifier group  901  composed of a plurality of operational amplifiers; a D/A converter group  902  composed of a plurality of D/A converters; and an output terminal group  903  composed of a plurality of output terminals. The D/A converter group  902  is connected to an input stage of the operational amplifier group  901 .  
           [0007]    The output terminal group  903  is connected to the liquid crystal panel  905  through a flexible substrate group  904  composed of a plurality of flexible substrates.  
           [0008]    The operational amplifier group  901  is composed of the operational amplifiers  806   a  shown in FIG. 8. Thus, the output terminals of the respective operational amplifiers of the operational amplifier group  901  are connected as the voltage follower so as to form the negative feedback circuit.  
           [0009]    The operational amplifier group  901  performs an impedance conversion on an analog signal outputted by the D/A converter group  902 . The operational amplifier group  901  charges and discharges the liquid crystal panel  905  serving as the capacitance load, on the basis of the signal on which the impedance conversion is performed.  
           [0010]    An invention in relation to a drive of a liquid crystal display using an operational amplifier, especially, an invention in relation to a power supply of a liquid crystal display driving circuit is disclosed in Japanese Laid Open Patent Application (JP-A-Showa, 62-83724). The technique disclosed in this gazette is the liquid crystal display driving circuit having the feature of protecting an oscillation of an operational amplifier by adding four resistors to a power supply circuit in which a six-level voltage is generated by using two kinds of power supplies, five resistors and four operational amplifiers. That is, this technique can protect a current increase caused by the oscillation of the operational amplifier. Incidentally, in order to protect the current increase, an output signal of the operational amplifier is outputted through the resistor and supplied to the liquid crystal panel.  
           [0011]    Conventionally, the liquid crystal panel driving circuit has been optimally designed by referring to an equivalent circuit of a liquid crystal panel. However, if a reactance component of the flexible substrate is large, the inductance component causes high impedance to be generated in a high frequency band. This high impedance brings about the situation that a signal to be attenuated by the liquid crystal panel is fed back to the liquid crystal driving circuit  906  without any attenuation. For this reason, in the high frequency band, the influence of the high impedance causes the deterioration of the frequency property of the operational amplifier group  901 . The deterioration of the frequency property results in the oscillation of the operational amplifier group  901 .  
           [0012]    Usually, the inductance component has a value of about 0.5 μH, although it is changed depending on the size of the liquid crystal panel. In the case of this condition, the input of a drive signal having a drive frequency of about 200 MHz may result in an occurrence of an oscillation.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention has been made to solve the above-explained problems.  
           [0014]    Therefore, an object of the present invention is to provide a liquid crystal panel driving circuit and a method of driving a liquid crystal panel, in which even if an inductance component is added between an operational amplifier and a liquid crystal panel, the operational amplifier is not oscillated.  
           [0015]    Another object of the present invention is to provide a liquid crystal panel driving circuit and a method of driving a liquid crystal panel, in which even if an inductance component is added between an operational amplifier and a liquid crystal panel, a speed for driving the liquid crystal panel are not deteriorated.  
           [0016]    Still another object of the present invention is to provide a liquid crystal panel driving circuit and method of driving a liquid crystal panel, in which even if an inductance component is added between an operational amplifier and a liquid crystal panel, a static current are not deteriorated.  
           [0017]    In order to achieve an aspect of the present invention, the present invention provides a liquid crystal panel driving circuit including an operational amplifier which outputs an output signal based on an image signal and an feedback signal corresponding to the output signal without a high frequency content; and a flexible substrate with an inductance wherein the output signal pass through to a liquid crystal display via the inductance.  
           [0018]    In the liquid crystal panel driving circuit, the operational amplifier may includes an operational amplifier element including a non-inverting input terminal supplied with the image signal, an inverting input terminal supplied with the feedback signal and an output terminal outputting the output signal; and a negative feedback circuit formed between the output terminal and the inverting input terminal.  
           [0019]    In the liquid crystal panel driving circuit, the negative feedback circuit may include a low pass filter attenuating the high frequency content.  
           [0020]    In the liquid crystal panel driving circuit, the low pass filter may includes a resistor connected between the inverting input terminal and the output terminal; and a capacitor connected between the inverting input terminal and an power supply.  
           [0021]    In the liquid crystal panel driving circuit, the low pass filter may includes a plurality of resistors connected in series between the inverting input terminal and the output terminal; and a plurality of capacitors connected in parallel to each other through the resistors, wherein one end of the each of plurality of capacitors is connected to a connection point between the resistors and the other end of the each capacitor is connected to a power supply.  
           [0022]    In the liquid crystal panel driving circuit, the low pass filter may further includes a plurality of switches, wherein the each of plurality of switches sets an active state and an inactive state of a corresponding one of the plurality of capacitors.  
           [0023]    In the liquid crystal panel driving circuit, it may further includes a control circuit controlling an active state and an inactive state of the each switch so as to set a synthesis capacitance of the plurality of capacitors, based on the inductance of the flexible substrate.  
           [0024]    In the liquid crystal panel driving circuit, it may further include D/A converter converting a digital image signal to an analog image signal as the image signal.  
           [0025]    In order to achieve another aspect of the present invention, the present invention provides a method of driving a liquid crystal panel including (a) amplifying an image signal as a output signal, (b) supplying a liquid crystal display with the output signal; and (c) feeding back an feedback signal based on the output signal without a high frequency content.  
           [0026]    In the method of driving a liquid crystal panel, (a) amplifying step includes (d) supplying an operational amplifier element with the image signal and the feedback signal; and (e) amplifying the image signal based on the image signal and the feedback signal by the operational amplifier element.  
           [0027]    In the method of driving a liquid crystal panel, (b) supplying step includes (f) supplying the output signal that passes through a flexible substrate with an inductance to the liquid crystal display via the inductance.  
           [0028]    In the method of driving a liquid crystal panel, (c) feeding back step includes (g) feeding back the feedback to the operational amplifier element, wherein the high frequency content signal is attenuated. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a view showing an arrangement of a conventional operational amplifier for a liquid crystal panel;  
         [0030]    [0030]FIG. 2 is a conceptual view of a conventional liquid crystal panel driving circuit;  
         [0031]    [0031]FIG. 3 is a view showing a configuration of an operational amplifier for driving a liquid crystal panel according to the first embodiment of the present invention;  
         [0032]    [0032]FIG. 4 is a view showing a configuration of an operational amplifier for driving a liquid crystal panel according to the second embodiment of the present invention;  
         [0033]    [0033]FIG. 5 is a view showing a configuration of an operational amplifier for driving a liquid crystal panel according to the third embodiment of the present invention;  
         [0034]    [0034]FIG. 6 is a view showing a configuration of an operational amplifier for driving a liquid crystal panel according to the fourth embodiment of the present invention;  
         [0035]    [0035]FIG. 7 is a view showing a configuration of the first liquid crystal panel driving circuit according to the present invention;  
         [0036]    [0036]FIG. 8 is a view showing a configuration of the second liquid crystal panel driving circuit according to the present invention;  
         [0037]    [0037]FIG. 9A is a view showing a property wave form when a low pass filter according to the present invention is not actuated; and  
         [0038]    [0038]FIG. 9B is a view showing a property wave form when the low pass filter according to the present invention is actuated. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    The embodiments of an operational amplifier for driving a liquid crystal panel according to the present invention and a liquid crystal panel driving circuit will be described below with reference to the attached drawings.  
         [0040]    [0040]FIG. 1 is a view showing the configuration of an operational amplifier for driving a liquid crystal panel, according to the first embodiment of the present invention.  
         [0041]    An operational amplifier  108   a  shown in FIG. 1 is provided with an operational amplifier element  108 , a resistor  111  and a capacitor  121 . The operational amplifier element  108  is composed of a non-inverting input terminal  102 , an output terminal  103  and an inverting input terminal  104 .  
         [0042]    The output terminal  103  is connected through the resistor  111  to the inverting input terminal  104 . Moreover, the output terminal  103  is connected through the resistor  111  and the capacitor  121  to a power supply  107 . A negative feedback circuit is constituted by the connection between the output terminal  103  and the inverting input terminal  104 . The resistor  111  and the capacitor  121  constitute a so-called low pass filter.  
         [0043]    As a value of the resistor  111 , a value from several ten Ω to several hundred Ω is defined depending on a frequency of a drive signal and a value of an inductance. As a value of the capacitor  121 , a value from several pF to several ten pF is defined depending on the frequency of the drive signal and the value of the inductance. If the frequency of the drive signal is, for example, about 200 MHz, a value of about 400 Ω is set for the resistor  111 , and a value of about 2 pF is set for the capacitor  121 .  
         [0044]    A liquid crystal panel  106  is connected through a flexible substrate  105  to the output terminal  103 .  
         [0045]    In the operational amplifier  108   a  having the above-mentioned configuration, an output signal corresponding to a signal input to the non-inverting input terminal  102  is outputted from the output terminal  103 . The output signal outputted from the output terminal  103  controls the operation for charging and discharging the liquid crystal panel  106  serving as a capacitance load, through the flexible substrate  105 .  
         [0046]    Incidentally, the feedback signal from the liquid crystal panel  106  is attenuated by the resistor  111  and the capacitor  121 , and it does not reach the inverting input terminal  104 . Conventionally, in a high frequency band, an inductance component of the flexible substrate  105  becomes high impedance. Therefore, the feedback signal to be attenuated in the liquid crystal panel  106  is not attenuated. However, in the present invention, the signal to be fed back is attenuated by the effects of the resistor  111  and the capacitor  121 . Thus, the oscillation of the operational amplifier  108   a  (operational amplifier element  108 ) is prevented.  
         [0047]    The second embodiment of the operational amplifier according to the present invention will be described below with reference to FIG. 2. FIG. 2 is a view showing the configuration of an operational amplifier for driving a liquid crystal panel, according to the second embodiment of the present invention.  
         [0048]    An operational amplifier  209   a  shown in FIG. 2 is provided with an operational amplifier element  209 , a resistor group  211  and a capacitor group  221 . The operational amplifier element  209  is composed of a non-inverting input terminal  203 , an output terminal  204  and an inverting input terminal  205 . The resistor group  211  is composed of a plurality of resistors connected in series with one after another (between the inverting input terminal  205  and the output terminal  204 ). The capacitor group  221  is composed of a plurality of capacitors connected in parallel to each other through the resistors.  
         [0049]    The output terminal  204  is connected through the resistor group  211  to the inverting input terminal  205 . Moreover, one end of each capacitor of the capacitor group  221  is connected to the connection point between the resistors. The other end of each capacitor is connected to a power supply  208 .  
         [0050]    A negative feedback circuit is formed by the connection between the output terminal  103  and the - inverting input terminal  104 . The resistor group  211  and the capacitor group  221  constitute a so-called low pass filter.  
         [0051]    The output terminal  204  is connected through a flexible substrate  206  to a liquid crystal panel  207 .  
         [0052]    In the operational amplifier  209   a  having the above-mentioned configuration, an output signal corresponding to a signal input to the non-inverting input terminal  203  is outputted from the output terminal  204 . The output signal outputted from the output terminal  204  controls the operation for charging and discharging the liquid crystal panel  207  serving as the capacitance load, through the flexible substrate  206 .  
         [0053]    Incidentally, the feedback signal from the liquid crystal panel  207  is attenuated by the resistor group  211  and the capacitor group  221 , and it does not reach the inverting input terminal  205 . Conventionally, in the high frequency band, an inductance component of the flexible substrate  206  becomes high impedance. Therefore, the feedback signal to be attenuated in the liquid crystal panel  207  is not attenuated. However, the signal to be fed back is attenuated by the effects of the resistor group  211  and the capacitor group  221 . Thus, the oscillation of the operational amplifier  209   a  (operational amplifier element  209 ) is prevented.  
         [0054]    The third embodiment according to the present invention will be described below with reference to FIG. 3. FIG. 3 is a view showing the configuration of an operational amplifier for driving a liquid crystal panel, according to the third embodiment of the present invention.  
         [0055]    An operational amplifier  308   a  shown in FIG. 3 is provided with an operational amplifier element  308 , a resistor group  311 , a capacitor group  321 , the first switch group (SWa)  331  and the second switch group (SWb)  332 . The operational amplifier element  308  is composed of a non-inverting input terminal  302 , an output terminal  303  and an inverting input terminal  304 . The resistor group  311  is composed of a plurality of resistors connected in series with one after another (between the inverting input terminal  304  and the output terminal  303 ). The capacitor group  321  is composed of a plurality of capacitors. The first switch group  331  is composed of a plurality of switches. The second switch group  332  is composed of a plurality of switches.  
         [0056]    The output terminal  303  is connected through the resistor group  311  to the inverting input terminal  304 . The first switch corresponding in the first switch group  331  is connected in parallel to each capacitor of the capacitor group  221 . One end of each capacitor is connected to the connection point between the resistors. The other end of each capacitor is connected through a second switch corresponding in the second switch group  332  to the power supply  307 .  
         [0057]    A negative feedback circuit is formed by the connection between the output terminal  303  and the inverting input terminal  304 . The resistor group  311 , the capacitor group  321 , the first switch group  331  and the second switch group  332  constitute a so-called low pass filter.  
         [0058]    The output terminal  303  is connected through a flexible substrate  305  to a liquid crystal panel  306 .  
         [0059]    In the operational amplifier  308   a  having the above-mentioned configuration, a signal input to the non-inverting input terminal  302  is outputted through the operational amplifier  308 , and controls the operation for charging and discharging the liquid crystal panel load  306  serving as the capacitance load. As for a feedback signal from the liquid crystal panel  306 , an attenuation amount is adjusted by the capacitor selected by the resistor group  311 , the first switch group  331  and the second switch group  332 . The feedback signal is attenuated in accordance with the attenuation in the resistor group  311  and the capacitor group  321 . Incidentally, if the first switch is turned on, the corresponding second switch is turned off. Similarly, if the first switch is turned off, the corresponding first switch is turned on.  
         [0060]    By suitably controlling the on/off operations of the first switch group  311  and the second switch group  332 , the synthesis capacitance of the capacitor group  321  can be defined in accordance with the reactance value of the flexible substrate  305 .  
         [0061]    The fourth embodiment according to the present invention will be described below with reference to FIG. 4. FIG. 4 is a view showing the configuration of an operational amplifier for driving a liquid crystal panel, according to the fourth embodiment of the present invention.  
         [0062]    An operational amplifier  408   a  shown in FIG. 4 is provided with an operational amplifier element  408 , a resistor group  411 , a capacitor group  421  and a switch group (SW)  431 . The operational amplifier element  408  is composed of a non-inverting input terminal  402 , an output terminal  403  and an inverting input terminal  404 . The resistor group  411  is composed of a plurality of resistors connected in series with one after another (between the inverting input terminal  404  and the output terminal  403 ). The capacitor group  421  is composed of a plurality of capacitors. The switch group  431  is composed of a plurality of switches.  
         [0063]    The output terminal  403  is connected through the resistor group  411  to the inverting input terminal  404 . One end of each capacitor of the capacitor group  421  is connected to the connection point between the resistors. The other end of each capacitor is connected through a switch corresponding in the switch group  432  to the power supply  407 .  
         [0064]    A negative feedback circuit is formed by the connection between the output terminal  403  and the inverting input terminal  404 . The resistor group  411 , the capacitor group  421  and the switch group  431  constitute a so-called low pass filter.  
         [0065]    The output terminal  403  is connected through a flexible substrate  405  to a liquid crystal panel  406 .  
         [0066]    In the operational amplifier  408   a  having the above-mentioned configuration, a signal input to the non-inverting input terminal  402  is outputted through the operational amplifier  408 , and controls the operation for charging and discharging the liquid crystal panel load  406  serving as the capacitance load. As for a feedback signal from the liquid crystal panel  406 , an attenuation amount is adjusted by the capacitor selected by the resistor group  411  and the switch group  431 . The feedback signal is attenuated in accordance with the attenuation in the resistor group  411  and the capacitor group  421 .  
         [0067]    By suitably controlling the on/off operations of the switch group  431 , the synthesis capacitance of the capacitor group  421  can be defined in accordance with the reactance value of the flexible substrate  405 .  
         [0068]    The configuration of a first liquid crystal panel driving circuit according to the present invention will be described below with reference to FIG. 5. FIG. 5 is a view showing the configuration of the first liquid crystal panel driving circuit according to the present invention.  
         [0069]    A liquid crystal panel driving circuit  506  shown in FIG. 5 is provided with an operational amplifier group  501  composed of a plurality of operational amplifiers, a D/A converter group  502  composed of a plurality of D/A converters; and an output terminal group  503  composed of a plurality of output terminals. The D/A converter group  502  is connected to an input stage of the operational amplifier group  501 .  
         [0070]    The output terminal group  503  is connected to a liquid crystal panel  505  through a flexible substrate group  504  composed of a plurality of flexible substrates.  
         [0071]    The operational amplifier group  501  is composed of the operational amplifiers  108   a  shown in FIG. 1 or the operational amplifiers  209   a  shown in FIG. 2. Thus, the output terminal of each operational amplifier of the operational amplifier group  501  is connected as the voltage follower so as to form the negative feedback circuit.  
         [0072]    A picture signal (digital signal) outputted by a picture signal generator (not shown) is sent to the D/A converter group  502 . This picture signal has data amounts in which its number corresponds to the number of pixels. The operational amplifier group  501  performs an impedance conversion on an analog signal outputted by the D/A converter group  502 . The operational amplifier group  501  charges and discharges the liquid crystal panel  505  serving as the capacitance load, on the basis of the signal on which the impedance conversion is performed.  
         [0073]    A feedback signal from the liquid crystal panel  505  is attenuated by the negative feedback circuit of the operational amplifier group  501 .  
         [0074]    Here, a configuration of a second liquid crystal panel driving circuit according to the present invention will be described below with reference to FIG. 6. FIG. 6 is a view showing the configuration of the second liquid crystal panel driving circuit according to the present invention.  
         [0075]    A liquid crystal panel driving circuit  607  shown in FIG. 6 is provided with an operational amplifier group  601  composed of a plurality of operational amplifiers, a D/A converter group  602  composed of a plurality of D/A converters, an output terminal group  603  composed of a plurality of output terminals, and a switch unit controller  606 . The D/A converter group  602  is connected to an input stage of the operational amplifier group  601 . The switch unit controller  606  is connected to the operational amplifier group  601   
         [0076]    The output terminal group  603  is connected to a liquid crystal panel  605  through a flexible substrate group  604  composed of a plurality of flexible substrates.  
         [0077]    The operational amplifier group  601  is composed of the operational amplifiers  308   a  shown in FIG. 3 or the operational amplifiers  408   a  shown in FIG. 4. Thus, the output terminal of each operational amplifier of the operational amplifier group  601  is connected as the voltage follower so as to form the negative feedback circuit. Also, the on/off controls of the first switch group  331 , the second switch group  332  and the switch group  431  are carried out in accordance with the control of the switch unit controller  606 . The synthesis capacitance of the capacitor groups  321 ,  421  is suitably defined in accordance with the on/off controls.  
         [0078]    The operational amplifier group  501  performs the impedance conversion on an analog signal outputted by the D/A converter group  502 . The operational amplifier group  501  charges and discharges the liquid crystal panel  505  serving as the capacitance load, on the basis of the signal on which the impedance conversion is performed.  
         [0079]    The feedback signal from the liquid crystal panel  505  is attenuated by the negative feedback circuit of the operational amplifier group  501   
         [0080]    The operational property of the liquid crystal panel driving circuit according to the present invention will be described below with reference to FIGS. 7A, 7B. FIG. 7A shows a wave form when a low pass filter according to the present invention is not actuated. FIG. 7B shows a wave form when a low pass filter according to the present invention is actuated.  
         [0081]    [0081]FIGS. 7A, 7B show the wave forms in a case of a flexible substrate inductance value L=0.5 μH. In FIGS. 7A, 7B, a horizontal axis indicates a frequency of a drive signal, and a vertical axis indicates a phase value corresponding to a phase curve and a gain value corresponding to a gain curve.  
         [0082]    In FIGS. 7A, 7B, the gain curve indicate the gain of the operational amplifier with respect to each frequency. In FIGS. 7A, 7B, the phase curve indicate a phase difference between a non-inverting input and an inverting input of the operational amplifier with respect to each frequency.  
         [0083]    In FIGS. 7A, 7B, the situation is induced in which the phase curve is changed by about 0 to 180 degrees, associated with the increase in the frequency. In this situation, the gain of “1” or more causes the oscillation of the operational amplifier.  
         [0084]    In FIG. 7A, in the situation in which the phase curve is changed by about 0 to 180 degrees, the gain is increased to “1” or more. The oscillation of the operational amplifier occurs in the operational amplifier (the conventional liquid crystal panel driving circuit) having such property.  
         [0085]    On the other hand, in FIG. 7B, the situation having the gain of “1” or more is not present in any frequency. Thus, the oscillation corresponding to the frequency does not occur in the operational amplifier according to the present invention.  
         [0086]    As mentioned above, the liquid crystal panel driving circuit according to the present invention can avoid the influence of the inductance component in the flexible substrate, on the basis of the capacitance of the feedback circuit. Thus, it is possible to prevent the oscillation of the operational amplifier that is caused by the inductance component.  
         [0087]    As mentioned above, the liquid crystal panel driving circuit according to the present invention can avoid the oscillation of the operational amplifier or the distortion of the output without any deterioration in the speed when the liquid crystal panel is driven and the static current, even if the inductance component of the flexible substrate that is the medium combined by the liquid crystal panel driving circuit and the liquid crystal panel is large.  
         [0088]    According to the above-mentioned configuration, if a latter stage of the operationally driving amplifier indicates the high impedance state because of the inductance component in the high frequency band, the feedback signal is attenuated by the load connected to the negative feedback circuit. Due to this action of the attenuation, the operational amplifier is protected against the oscillation, and it is stably operated. Incidentally, in the configuration according to the present invention, the capacitor and the resistor are not connected in series between the liquid crystal panel and the output terminal of the operational amplifier. So, the speed when the liquid crystal panel is driven is not deteriorated. Moreover, there is no technical idea of increasing the current supplied to the operational amplifier and thereby making the operational amplifier stable. Hence, the static current value is never increased.