KR101400864B1 - Adaptive circuit for dividing impedance and feedback circuit employing the same - Google Patents

Adaptive circuit for dividing impedance and feedback circuit employing the same Download PDF

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Publication number
KR101400864B1
KR101400864B1 KR1020120009536A KR20120009536A KR101400864B1 KR 101400864 B1 KR101400864 B1 KR 101400864B1 KR 1020120009536 A KR1020120009536 A KR 1020120009536A KR 20120009536 A KR20120009536 A KR 20120009536A KR 101400864 B1 KR101400864 B1 KR 101400864B1
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output
voltage
impedance
variable
ground
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KR1020120009536A
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Korean (ko)
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KR20130088351A (en
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최영하
이은석
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네오피델리티 주식회사
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Abstract

The present invention relates to an adaptive impedance divider circuit and a feedback circuit using the adaptive impedance divider circuit. According to the present invention, it is possible to provide an adaptive impedance dividing circuit for adaptively distributing a variable voltage and outputting a normalized output voltage, and a feedback circuit using the adaptive impedance dividing circuit.

Description

ADAPTIVE CIRCUIT FOR DIVIDING IMPEDANCE AND FEEDBACK CIRCUIT EMPLOYING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adaptive impedance divider circuit and a feedback circuit using the adaptive impedance divider circuit, and more particularly, to an adaptive impedance divider circuit that adaptively distributes a variable voltage to output a normalized output voltage and a feedback circuit using the adaptive impedance divider.

In an electronic device such as a digital amplifier, an unstable power supply with ripple hinders the performance of electronic devices. For example, if ripple is included in the power supply of the digital amplifier, a distorted acoustic signal is output.

Specifically, a digital amplifier amplifies an input signal through switching, amplifies the output signal, and converts the amplified output signal into an analog signal through a low-pass filter. At this time, if the digital amplifier power supply includes ripple during the amplification process, an output signal reflecting the ripple of the power supply is generated.

In order to minimize the distortion of the output signal, a circuit that compares the output signal with the input signal can be used. Since the output signal is a signal obtained by amplifying the input signal, the levels of the two signals must be matched in order to compare the output signal and the input signal.

However, since the level of the output signal depends on the amplification degree of the digital amplifier, there is a problem that the design of the comparison circuit must be changed according to the amplification degree of the digital amplifier. Thus, there is a need for a circuit that can normalize the output signal of various levels to the level of the input signal.

In order to solve the above problems, an object of the present invention is to provide an adaptive impedance divider circuit that adaptively distributes a variable voltage to output a normalized output voltage and a feedback circuit using the adaptive impedance divider circuit.

The adaptive impedance divider according to the present invention includes: a fixed impedance unit connected to an input terminal and an output terminal; A variable impedance unit connected to the output terminal and the ground; A low band filter unit for generating a DC voltage from an output voltage applied to the output terminal; And a control unit controlling the impedance of the variable impedance unit based on the reference voltage and the direct current voltage to maintain the output voltage constant in accordance with the change of the input voltage.

The impedance of the variable impedance unit may be determined according to the magnitude of an input voltage applied to the input terminal.

The control unit may include an operational amplifier (OP-AMP) to which the DC voltage is applied to the inverting input terminal and the reference voltage is applied to the non-inverting input terminal.

The variable impedance unit includes a first resistor connected to the output terminal and the ground; And a transistor connected to the output terminal, the output terminal, and the ground of the operational amplifier.

The control unit may control the transistor to operate in a linear region.

The transistor may comprise a MOSFET.

The fixed impedance portion may include a second resistor.

The low-pass filter section includes a third resistor connected to the output terminal and the inverting input terminal; And a capacitor connected to the inverting input and ground.

The feedback circuit using the adaptive impedance divider circuit according to the present invention includes: a main circuit for generating an output signal; An adaptive impedance divider circuit for generating a feedback signal based on the output signal; And an adder for adding the inverted input signal and the feedback signal to input to the main circuit, wherein the adaptive impedance divider circuit includes: a fixed impedance unit connected to an input end and an output end; A variable impedance unit connected to the output terminal and the ground; A low band filter unit for generating a DC voltage from an output voltage applied to the output terminal; And a control unit for controlling the impedance of the variable impedance unit based on the reference voltage and the DC voltage to determine the output voltage.

The impedance of the variable impedance unit may be determined according to the magnitude of an input voltage applied to the input terminal.

The control unit may include an operational amplifier (OP-AMP) to which the DC voltage is applied to the inverting input terminal and the reference voltage is applied to the non-inverting input terminal.

The variable impedance unit includes a first resistor connected to the output terminal and the ground; And a transistor connected to the output terminal, the output terminal, and the ground of the operational amplifier.

The control unit may control the transistor to operate in a linear region.

The transistor may comprise a MOSFET.

The fixed impedance portion may include a second resistor.

The low-pass filter section includes a third resistor connected to the output terminal and the inverting input terminal; And a capacitor connected to the inverting input and ground.

The adaptive impedance divider circuit and the feedback circuit using the adaptive impedance divider according to the present invention have the following advantages.

The adaptive impedance divider circuit according to the present invention can adaptively distribute a variable voltage and output a normalized output voltage. That is, since the input signal can be converted into a signal of a specific level in accordance with the level of the input signal (variable voltage), the circuit design can be changed according to the level of the input signal.

Further, by using the feedback circuit using the adaptive impedance division circuit according to the present invention, the output signal of the main circuit can be normalized to the level of the input signal and compared with the input signal. That is, even if the level of the output signal changes, the output signal can be made to coincide with the level of the input signal, so that the distortion of the output signal can be reduced by comparing the input signal with the output signal converted to the level of the input signal.

1 is a block diagram showing an adaptive impedance divider circuit according to the present invention;
FIG. 2A is a graph showing an example of a variable voltage applied to the adaptive impedance division circuit according to the present invention; FIG.
FIG. 2B is a graph showing the output voltage of the adaptive impedance division circuit according to the present invention to which the variable voltage of FIG. 2A is applied. FIG.
3 is a schematic diagram showing an adaptive impedance circuit according to a first embodiment of the present invention;
4 is a graph showing the drain current Ids and the drain-source voltage Vds according to the gate voltage Vgs of the MOSFET.
5 is a block diagram showing a feedback circuit using an adaptive impedance divider circuit according to the present invention;

Hereinafter, preferred embodiments of the adaptive impedance divider circuit according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing an adaptive impedance divider circuit according to the present invention.

1, the adaptive impedance divider according to the present invention includes a fixed impedance unit 110, a variable impedance unit 120, a low-pass filter unit 130, and a control unit 140.

The fixed impedance section 110 is connected between the input terminal 10 and the output terminal 20 and has a constant impedance.

A variable voltage is applied to the input terminal 10. For example, a variable voltage varying in the range of 7.5 to 26 [V] may be applied to the input terminal 10.

The output stage 20 adaptively distributes the variable voltage to output a normalized output voltage. Specifically, the ratio of the voltage distribution is determined by the ratio of the impedance of the fixed impedance section 110 to the impedance of the variable impedance section 120. The detailed process of adaptively distributing the variable voltage and outputting the normalized output voltage will be described in detail in the first embodiment.

The variable impedance unit 120 is connected to the output terminal 20 and the ground, and the impedance of the variable impedance unit 120 is determined by the control unit 140. The variable impedance unit 120 forms a voltage divider circuit together with the fixed impedance unit 110, and the output voltage is determined according to the impedance of the variable impedance unit 120. In addition, the impedance of the variable impedance unit 120 may be adapted to the magnitude of the variable voltage applied to the input terminal 10.

The low band filter unit 130 is connected to the output stage 20 and the control unit 140 and generates a DC voltage from an output voltage applied to the output stage 20. [ The DC voltage generated by the low-pass filter unit 130 is applied to the control unit 140 which controls the impedance of the variable impedance unit 120.

The control unit 140 controls the impedance of the variable impedance unit 120 based on the reference voltage and the DC voltage generated by the low-pass filter unit 130 to normalize the output voltage.

The control unit 140 adaptively controls the impedance of the variable impedance unit 120 according to the magnitude of the DC component included in the variable voltage (the DC voltage generated by the low-pass filter unit 130) to normalize the output voltage .

2A is a graph showing an example of a variable voltage applied to the adaptive impedance division circuit according to the present invention.

Referring to FIG. 2A, input voltages applied to the adaptive impedance divider according to the present invention may have different DC components and AC components, respectively. Specifically, in the graph of FIG. 2A, the input voltage with the largest DC component has a DC component of about 24V, and includes an AC component with an amplitude of about 5V. Also, the input voltage having the smallest direct current component has a direct current component of about 12V and includes an alternating current component of about 2V amplitude.

FIG. 2B is a graph showing the output voltage when the variable voltage of FIG. 2A is applied to the adaptive impedance divider circuit according to the present invention. FIG.

Referring to FIG. 2B, the adaptive impedance divider circuit according to the present invention normalizes and outputs each input voltage having a different DC component and an AC component. Specifically, all the output voltages obtained by normalizing the variable voltage in Fig. 2A have a DC component of 1V. In addition, each input voltage in Fig. 2A includes an AC component with an amplitude of about 5V to about 2V, but the output voltage in Fig. 2B only includes an AC component with an amplitude of less than 0.4. That is, by using the adaptive impedance divider circuit according to the present invention, it is possible to output an output voltage having a DC component having a constant magnitude and an AC component having a magnitude similar in magnitude when a variable voltage is applied.

Fig. 3 is a schematic diagram showing an adaptive impedance circuit according to the first embodiment of the present invention, and shows a specific configuration of each block.

3, the control unit 140 includes an operational amplifier 141 (OP-AMP) to which a DC voltage and a reference voltage are respectively applied to an inverting input terminal and a non-inverting input terminal and an output is applied to the variable impedance unit .

The DC voltage applied to the inverting input terminal is generated by the low-band filter unit 130 using the output voltage of the output terminal 20, and corresponds to the DC component of the output voltage.

The operational amplifier 141 applies the generated output based on the reference voltage and the direct current voltage to the variable impedance section 120.

The variable impedance section 120 preferably includes a first resistor 121 and a transistor 122.

The first resistor 121 may be connected to the output terminal 20 and the ground.

The transistor 122 is preferably connected to the output stage 20, the operational amplifier 141 and the ground.

That is, the first resistor and the transistor may be connected in parallel. The value of the first resistor is fixed, and the impedance of the transistor is determined according to the output of the operational amplifier. Assuming that the value of the first resistor is a and the impedance of the transistor is x, the impedance of the variable impedance portion has a value of 1 / (1 / a + 1 / x) Impedance is determined by impedance.

In addition, the transistor 122 may include a metal oxide semiconductor field-effect transistor (MOSFET). When the transistor 122 is a MOSFET, the gate may be connected to the output terminal of the operational amplifier 141, the drain may be connected to the output terminal 20, and the source may be connected to the ground.

4 is a graph showing the drain current Ids and the drain-source voltage Vds according to the gate voltage Vgs of the MOSFET.

Referring to FIG. 4, as the gate voltage Vgs increases, a larger drain-source voltage Vds is required for the MOSFET to operate in the saturation region. That is, when the MOSFET operates in the linear region, the slope of the graph changes as the gate voltage Vgs increases at the same drain-source voltage Vds. For example, when the drain-source voltage Vds is Vds1, the slope of the tangent line increases as the gate voltage Vgs increases from Vgs3 to Vgs6. Since the X and Y axes of the graph are the dimensions of the voltage and current, respectively, an increase in the slope of the tangent means a decrease in the impedance.

For example, if the impedance of the fixed impedance section is 9 [ohm], the first resistor is 2 [ohm], the DC component of the variable voltage is 20 [V], and the reference voltage is 1 [V] Is applied to the MOSFET. Assuming that the value corresponding to 19 [V] is Vgs6 and the impedance of the MOSFET is 18/29 [ohm] (about 0.62 [ohm]), the impedance of the variable impedance portion is 9/19 [ohm] (about 0.47 [ohm]) do. The DC component of the output voltage is converted to 1 [V] because the fixed impedance portion and the variable impedance portion are distributed at a ratio of 9: 9/19 at a variable voltage of 20 [V].

The DC component of the variable voltage in the circuit under the above conditions can be changed to 10 [V]. The operational amplifier applies a value corresponding to 9 [V] which is the difference between the DC component of the variable voltage and the reference voltage to the MOSFET. Assuming that the value corresponding to 9 [V] is Vgs5 and the impedance of the MOSFET is 2 [ohm], the impedance of the variable impedance portion is 1 [ohm]. Since the variable impedance of 10 [V] is distributed at the fixed impedance part and the variable impedance part at the ratio of 9: 1, the DC component of the output voltage is converted to 1 [V].

That is, when the direct current component of the variable voltage is 20 [V], the output voltage of the 1 [V] direct current component is output by the voltage division, and even if the direct current component of the variable voltage changes to 10 [V] So that an output voltage having a direct current component of 1 [V] is output.

The low-pass filter unit 130 preferably includes a third resistor 131 and a capacitor 132.

The third resistor 131 may be connected to the output terminal 20 and the inverting input terminal of the operational amplifier 141.

Capacitor 132 may be coupled to the inverting input of operational amplifier 141 and ground. Since the AC component is short-circuited through the capacitor 132 connected to the ground, only the DC voltage is applied to the inverting input terminal of the operational amplifier 141.

The fixed impedance section 110 preferably includes a second resistor 111.

5 is a block diagram showing a feedback circuit using an adaptive impedance divider circuit according to the present invention.

5, the feedback circuit using the adaptive impedance divider circuit according to the present invention includes a main circuit 200, an adaptive impedance divider circuit 100, and an adder 300

The main circuit 200 generates an output signal based on the input signal and the feedback signal. For example, the main circuit 200 may be a digital amplifier that amplifies an input signal.

If the main circuit 200 is a digital amplifier, if ripple is included in the digital amplifier power supply during the amplification process, a distorted output signal is generated due to ripple. It is possible to reduce the distortion of the output signal by comparing the output signal with the input signal. Since the output signal is a signal obtained by amplifying the input signal, the level of the output signal and the input signal must be matched.

The adaptive impedance dividing circuit 100 generates a normalized feedback signal based on the output signal generated by the main circuit 200. [ The feedback signal may be generated by distributing the voltage so that the output signal matches the level of the input signal.

When the main circuit 200 is a digital amplifier, the magnitude of the output signal changes according to the amplification degree of the digital amplifier, so that the voltage division ratio must be changed according to the level of the output signal. The adaptive impedance divider circuit 100 according to the present invention can adaptively change the impedance of the variable impedance section according to the level of the output signal to generate a normalized feedback signal. Since the operation of the adaptive impedance divider circuit 100 for generating the normalized signal has been described with reference to FIGS. 1 to 4, detailed description thereof will be omitted.

The adder 300 adds the inverted input signal and the feedback signal and inputs the sum to the main circuit 200. Since the feedback signal is a signal obtained by converting the output signal into the level of the input signal, it can be used to reduce the distortion of the output signal by adding the inverted input signal and the feedback signal.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Modifications will be possible.

Therefore, the embodiments disclosed in the present specification are intended to illustrate rather than limit the present invention, and the scope and spirit of the present invention are not limited by these embodiments. The scope of the invention should be construed according to the following claims, and all the technical scope of the invention should be construed as being included in the scope of the present invention.

10: input terminal 20: output terminal
100: adaptive impedance divider circuit 110: fixed impedance unit
111: second resistor 120: variable impedance unit
121: first resistor 122: transistor
130: low-pass filter unit 131: third resistance
132: capacitor 140:
141: operational amplifier 200: main circuit
300: adder

Claims (14)

1. An adaptive impedance divider circuit comprising: an input terminal to which a variable voltage is applied; and an output terminal for adaptively distributing the variable voltage to output as an output voltage,
A fixed impedance unit connected between the input terminal and the output terminal;
A variable impedance unit connected between the output terminal and the ground;
A low band filter unit for generating a DC voltage from the output voltage;
And a control unit for adaptively controlling the impedance of the variable impedance unit based on the reference voltage and the DC voltage so that the output voltage is normalized,
, ≪ / RTI &
The control unit includes an operational amplifier (OP-AMP) to which the DC voltage and the reference voltage are respectively applied to an inverting input terminal and a non-inverting input terminal, and an output is applied to the variable impedance unit,
The variable impedance unit
A first resistor coupled between the output and the ground; And
The operational amplifier, the output terminal, and the transistor
Wherein the adaptive impedance divider circuit comprises:
delete
delete
The method according to claim 1,
Wherein the controller controls the transistor to operate in a linear region.
The method according to claim 1,
Wherein the transistor comprises a MOSFET having a gate connected to the operational amplifier, a drain connected to the output, and a source coupled to ground.
The method according to claim 1,
Wherein the fixed impedance portion comprises a second resistor.
The method according to claim 1,
The low-
A third resistor coupled between the output and the inverting input; And
A capacitor connected between the inverting input and ground,
Wherein the adaptive impedance divider circuit comprises:
A main circuit for generating an output signal;
An adaptive impedance divider circuit for generating a feedback signal based on the output signal; And
An adder for adding the inverted input signal and the feedback signal to the main circuit,
, ≪ / RTI &
Wherein the adaptive impedance divider circuit comprises:
1. An adaptive impedance divider circuit comprising: an input terminal to which a variable voltage is applied; and an output terminal for adaptively distributing the variable voltage to output as an output voltage,
A fixed impedance unit connected between the input terminal and the output terminal;
A variable impedance unit connected between the output terminal and the ground;
A low band filter unit for generating a DC voltage from the output voltage;
And a control unit for adaptively controlling the impedance of the variable impedance unit based on the reference voltage and the DC voltage so that the output voltage is normalized,
, ≪ / RTI &
The control unit includes an operational amplifier (OP-AMP) to which the DC voltage and the reference voltage are respectively applied to an inverting input terminal and a non-inverting input terminal, and an output is applied to the variable impedance unit,
The variable impedance unit
A first resistor coupled between the output and the ground; And
The operational amplifier, the output terminal, and the transistor
And a feedback circuit.
delete
delete
9. The method of claim 8,
Wherein the control unit controls the transistor to operate in a linear region.
9. The method of claim 8,
Wherein the transistor comprises a MOSFET having a gate connected to the operational amplifier, a drain connected to the output, and a source coupled to ground.
9. The method of claim 8,
And the fixed impedance portion comprises a second resistor.
9. The method of claim 8,
The low-
A third resistor coupled between the output and the inverting input; And
A capacitor connected between the inverting input and ground,
And a feedback circuit.
KR1020120009536A 2012-01-31 2012-01-31 Adaptive circuit for dividing impedance and feedback circuit employing the same KR101400864B1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR960014115B1 (en) * 1986-03-03 1996-10-14 밀톤 돌비 레이 Attanuator using bootstrapping
JP2003084723A (en) 2001-09-12 2003-03-19 Sharp Corp Power supply device and display device provided with the power supply device
KR20040058353A (en) * 2001-11-29 2004-07-03 산켄덴키 가부시키가이샤 Switching power supply
US20080136396A1 (en) 2006-12-06 2008-06-12 Benjamin Heilmann Voltage Regulator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR960014115B1 (en) * 1986-03-03 1996-10-14 밀톤 돌비 레이 Attanuator using bootstrapping
JP2003084723A (en) 2001-09-12 2003-03-19 Sharp Corp Power supply device and display device provided with the power supply device
KR20040058353A (en) * 2001-11-29 2004-07-03 산켄덴키 가부시키가이샤 Switching power supply
US20080136396A1 (en) 2006-12-06 2008-06-12 Benjamin Heilmann Voltage Regulator

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