JP2000050618A - Dc-to-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a lag behind the abrupt rising of an input signal with a high range and a large amplitude. SOLUTION: A DC/DC converter involving a DC/DC converter control signal generating circuit 30, in which an input signal is rectified for outputting by shifting DC, a DC/DC converter circuit W1 generating a switching signal based on the output signal of the DC/DC converter control signal generating circuit 30, and a DC/DC converter outputting circuit 34 generating and outputting an output signal based on the switching signal for outputting it outward, is provided with a controlling signal rising accelerating circuit 36 which generates a signal, based on the input signal, with a waveform of a rising edge part of a sine wave and which rises abruptly for feeding it to the DC/DC converter control signal generating circuit 30. The DC/DC converter controlling signal generating circuit 30 adds and combines the rectified input signal and the signal which are provided from the control signal rising accelerating circuit 36 for outputting by shifting DC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DC-DC converter, and more particularly, to a DC-DC converter suitable for use in an amplifier circuit used for power amplification of an audio signal or the like.
A DC converter in which a rising waveform of a voltage waveform of an output signal from a DC-DC converter is particularly improved.
A DC converter;

[0002]

2. Description of the Related Art Conventionally, among amplifier circuits for amplifying an audio signal, an amplifier circuit having a circuit configuration shown in FIG. 1 is known as an amplifier circuit for which high efficiency is achieved by using a DC-DC converter. ing.

This amplifier circuit inputs a signal (audio input signal) output from a signal source 10 to a power amplifier 12, amplifies an input signal in a voltage amplifier circuit 14 of the power amplifier 12, and outputs a signal to an output stage of the power amplifier 12. By driving the + side power transistor 16 and the − side power transistor 18 which are transistors, necessary power is supplied to the speaker 20 which is a load.

The power supply voltage + B generated by the power supply 22 for driving the + power transistor 16 is supplied by a + power supply DC-DC converter 24 connected between the power supply 22 and the + power transistor 16. Be lowered. That is, the + -side power transistor 16 is driven by lowering the power supply voltage + B by the + -side power supply DC-DC converter 24.

Similarly, a power supply voltage B generated by the power supply 26 for driving the negative power transistor 18 is supplied to a DC power supply DC-DC converter 28 connected between the power supply 26 and the negative power transistor 18. Is reduced by That is, the power supply voltage -B is reduced by the DC power supply 28 for the negative side power supply to drive the negative side power transistor 18.

That is, in the conventional amplifier circuit shown in FIG. 1, the power supply voltage + B and the power supply voltage -B are respectively used by using the + side power supply DC-DC converter 24 and the-side power supply DC-DC converter 28. By driving the power amplifier 12 while reducing the power loss, the loss due to heat generation in the power amplifier 12 is reduced while achieving high efficiency.

Here, the DC-DC converter 24 for the + side power supply and the DC-DC converter 28 for the-side power supply have an on / off ratio variable according to the output of the power amplifier 12 (control input by a control voltage signal). Is switched.

FIG. 2 shows a block diagram of a conventional DC-DC converter used as the DC-DC converter 24 for the + side power supply and the DC-DC converter 28 for the-side power supply. The DC converter includes a DC-DC converter control signal generation circuit 30 to which an output from the power amplifier 12 is supplied as an input signal;
A DC-DC converter IC 32 to which an output signal of the DC-DC converter control signal generation circuit 30 is input;
D to which the output signal of the DC converter IC 32 is input
And a C-DC converter output circuit 34. The output of the DC-DC converter output circuit 34
It is taken out as an output signal of the DC converter and supplied to the power amplifier 12, and is also subjected to negative feedback (NF: negative feedback) to the DC-DC converter control signal generation circuit 30.

FIG. 3 shows voltage waveforms at various parts of the conventional DC-DC converter (FIG. 2). Referring to FIG. 3, the conventional DC-DC converter (FIG. 2) Will be described.

First, at a point A, a voltage waveform of an output from the power amplifier 12 is given as a voltage waveform of an input signal to the DC-DC converter control signal generation circuit 30, and the waveform is, for example, It is a sine wave.

The DC-DC converter control signal generation circuit 30 rectifies and inverts the input signal having the waveform shown at point A, shifts DC, and outputs it to point C. D
The C-DC converter IC 32 receives the signal of the waveform at the point C and generates a switching signal as shown at the point D. Further, the DC-DC converter output circuit 34 outputs
The switching signal at the point is input, and an output signal having a voltage waveform for driving the power amplifier 12 shown at the point E is generated.

The DC-DC converter output circuit 34
Is output to the DC-DC converter control signal generation circuit 30 as described above, with negative feedback (NF:
Negative feedback).

In FIG. 4, a large amplitude signal having a frequency of 1 kHz is output from a signal source 10 and input to an amplifier 12 of an amplifier circuit (FIG. 1) using a conventional DC-DC converter (FIG. 2). FIG. 4 shows voltage waveforms at various points in the amplifier circuit shown in FIG. 1 at this time, and the operation of the amplifier circuit shown in FIG.

That is, in the + side circuit, the + side power supply D
The C-DC converter 24 variably switches the on / off ratio by a switching signal (voltage waveform at point D in FIG. 3) according to the output of the power amplifier 12 (control input by the control voltage signal), so that the power supply voltage + B (A) is reduced to a voltage (B) necessary and sufficient to extract necessary power from the power amplifier 12.

On the negative side, a DC power supply for the negative side
The DC converter 28 variably switches the on / off ratio by a switching signal according to the output of the power amplifier 12 (control input by a control voltage signal),
The power supply voltage -B (E) is reduced to a voltage (D) necessary and sufficient to extract necessary power from the power amplifier 12.

That is, according to this amplifier circuit, as shown in FIG. 4, the output voltage (B) of the DC-DC converter 24 for the + power supply and the output voltage (D) of the DC-DC converter 28 for the-power supply. Is changed following the output voltage (C) of the power amplifier 12, so that loss due to heat of the power transistor in the power amplifier 12 can be greatly reduced regardless of the magnitude of the output of the power amplifier 12. it can.

Also, a DC-DC converter 2 for the + side power supply
Since the DC-DC converter 4 and the-side power supply DC-DC converter 28 perform the switching drive as described above, the loss here is also small, and the efficiency of the whole amplifier circuit is extremely high.

However, the + side power supply DC-DC converter 24 and the-side power supply DC
The -DC converter 28 has a built-in smoothing circuit for smoothing the switching output waveform and supplying it to the power amplifier 12. For this reason, when a high-frequency (high-frequency) and large-amplitude (large-output) signal is input to the power amplifier 12, the power supply cannot follow the sharp rise of the input signal, and the power amplifier 12 Twelve outputs were clipping.

That is, FIG. 5 shows a voltage waveform at each part of the amplifier circuit shown in FIG. 1 when a high-amplitude signal having a frequency of 10 kHz is output as a high-frequency and large-amplitude signal and input to the power amplifier 12. When a signal having a large amplitude at a frequency of 10 kHz is output and input to the power amplifier 12, when the input signal sharply rises, the positive side power supply D
There has been a problem that the rising waveforms of the voltage waveforms (B, D) output from the C-DC converter 24 and the negative-side power supply DC-DC converter 28 have a delay.

For this reason, the power supply to the power amplifier 12 by the DC-DC converter 24 for the + side power supply and the DC-DC converter 28 for the − side power supply cannot follow.
The output (C) of the power amplifier 12 was clipped.

Although the "rise" originally indicates a change from a small value to a large value, in the present specification, the absolute value of the DC-DC converter 28 for the negative side power supply is also large. When it changes in a certain direction, the phrase "rise" is used.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional DC-DC converter, and an object thereof is to provide a DC-DC converter.
Improve the rising waveform of the voltage waveform of the converter output so that there is no delay even for the steep rising of the input signal of high frequency (high frequency) and large amplitude (high output), and high frequency (high frequency) And a DC- with improved followability to a steep rising of an input signal having a large amplitude (large output).
It is intended to provide a DC converter.

[0023]

In order to achieve the above-mentioned object, the present invention provides a DC-DC converter, in which a waveform obtained by performing half-wave rectification and differentiation of the input signal waveform is added to the waveform of the input signal. Thus, the rising waveform of the voltage waveform of the output of the DC-DC converter is improved.

That is, according to the first aspect of the present invention, a DC-DC converter control signal generation circuit for rectifying an input signal and then shifting and outputting a DC signal;
A DC-DC converter circuit that generates a switching signal based on an output signal of a DC converter control signal generation circuit, and a DC-DC converter output circuit that generates and outputs an output signal for outputting to the outside based on the switching signal In the DC-DC converter having the above, a signal having a waveform similar to a rising portion of a sine wave and having a sharply rising waveform is generated based on the input signal and supplied to the DC-DC converter control signal generation circuit. And a control signal rising speeding circuit.
The DC converter control signal generation circuit adds and synthesizes the rectified signal of the input signal and the signal supplied from the control signal rising speeding circuit, and then shifts and outputs DC.

Therefore, according to the first aspect of the present invention, the control signal rising speeding circuit has a waveform like a rising portion of a sine wave based on an input signal, and has a waveform rising sharply. A signal is generated and DC
-The DC converter control signal generation circuit adds and combines the signal obtained by rectifying the input signal and the signal supplied from the control signal rising speeding circuit, and then shifts and outputs DC. The rising waveform of the signal is sharpened, and as a result, the DC-D generated based on the signal having the sharp rising waveform is generated.
The rising waveform of the output signal of the C converter also becomes steep.

According to a second aspect of the present invention, in the first aspect of the present invention, the control signal rising speed-up circuit is supplied to the DC-DC converter control signal generating circuit. The waveform of the input signal is a waveform that rises at a time slightly earlier than the rise of the waveform of the input signal.

Therefore, according to the second aspect of the present invention, the voltage of the edge portion of the rising waveform of the signal when the signals are added and synthesized by the DC-DC converter control signal generation circuit is raised to a high level. , A waveform having a sharper rise can be obtained.

Here, the control signal rise speeding-up circuit includes, for example, a rectifier / buffer circuit for half-wave rectifying the input signal and outputting the input signal, as in the third aspect of the present invention.
A differential circuit that differentiates and outputs the output from the rectifier / buffer circuit, and an ideal diode circuit that rectifies the output from the differential circuit without loss and outputs the rectified output to the DC-DC converter control signal generation circuit. Things.

Further, the rectifier / buffer circuit may be, for example, a rectifier / buffer circuit configured to rectify the input signal by half-wave and a half-wave rectifier by the rectifier circuit. A buffer circuit that outputs the rectified input signal and a resistor that is inserted between the rectifier circuit and the buffer circuit and that shifts the level of the input signal to the negative side can be provided.

With this configuration, the waveform of the signal output through the differentiating circuit and the ideal diode circuit rises at a time slightly earlier than the rising of the waveform of the input signal.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a DC-DC converter according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 6 is a block diagram showing an example of an embodiment of a DC-DC converter according to the present invention.

The DC-DC converter shown in FIG. 6 is similar to the conventional DC-DC converter shown in FIG.
It shall be used for the amplifier circuit shown in FIG.

In the DC-DC converter shown in FIG. 6, the same or corresponding components as those of the conventional DC-DC converter shown in FIG. 2 are denoted by the same reference numerals as those used in FIG. Thus, detailed description thereof will be omitted.

That is, the DC-DC converter shown in FIG. 6 is provided with a control signal rising speed-up circuit 36 having an output from the power amplifier 12 as an input signal as compared with the conventional DC-DC converter shown in FIG. The output signal of the control signal rising speed-up circuit 36 is DC-D
The difference is that the power is supplied to the C converter control signal generation circuit 30. And DC-
The DC converter control signal generation circuit 30 adds and synthesizes an output signal from the control signal rise speed-up circuit 36 and a signal obtained by rectifying an input signal as an output from the power amplifier 12, and shifts and outputs DC. Is what you do.

Here, FIG. 7 shows a D signal according to the present invention when a signal having a frequency of 5 kHz is input from the power amplifier 12.
FIG. 8 shows voltage waveforms at various parts of the C-DC converter (FIG. 6).
FIG. 6 shows voltage waveforms at various parts of the DC-DC converter according to the present invention (FIG. 6) at the time of inputting a signal of Hz.
An outline of the operation of the DC converter (FIG. 6) will be described.

First, at point A, the power amplifier 12
Is given as an input signal, and its voltage waveform is, for example, a frequency of 5 k in the case shown in FIG.
Hz sine wave, and in the case shown in FIG.
z sine wave. In FIG. 8, illustration of the voltage waveform at point A is omitted.

Then, the control signal rise speeding-up circuit 3
At 6, the signal having the voltage waveform shown at the point A rises at a time slightly higher than the rising of the waveform shown at the point A while the voltage waveform shown at the point B (a waveform like a rising portion of a sine wave rises sharply). ), And a DC-DC converter control signal generation circuit 3
Output to 0.

The control signal rising speeding circuit 36
From the detailed structure of the voltage waveform signal shown at point A
For details of the operation of generating the signal of the voltage waveform indicated by the dot,
This will be described later in detail with reference to FIGS.

DC-DC converter control signal generation circuit 3
In the case of 0, a signal having a voltage waveform shown at a point C is generated by adding and synthesizing a signal obtained by rectifying the voltage waveform shown at a point A and a signal having a voltage waveform shown at a point B. That is, the voltage waveform of the signal obtained at the point C is a waveform protruding downward (negative direction), and the voltage at the fall is sharply reduced, the fall is sharp, and the voltage shown at the point B is high. Since the waveform rises at a time slightly earlier than the rise of the voltage waveform shown at the point A, the voltage waveform falls at a time slightly earlier than the rise of the voltage waveform shown at the point A.

The DC-DC converter IC 32 receives the signal having the voltage waveform shown at the point C and generates a switching signal as shown at the point D in accordance with the voltage waveform shown at the point C. In FIG. 8, the illustration of the voltage waveform at point D is omitted.

Further, a DC-DC converter output circuit 3
Reference numeral 4 receives the switching signal shown at point D and generates a signal having a voltage waveform at point E for driving the power amplifier 12.

As shown in FIG. 7 and FIG. 8, the voltage waveform of the signal at the point E generated as described above has a rising voltage irrespective of the frequency, and the rising voltage waveform becomes steep. Since the voltage waveform obtained at the point C falls at a time slightly earlier than the rise of the voltage waveform shown at the point A, the voltage at the edge portion of the rising voltage waveform can be raised higher. It is possible to reliably eliminate the delay of the input signal having a high frequency (high frequency) and a large amplitude (large output) with respect to a steep rise of the input signal. It is possible to follow the steep rising with a margin.

Next, the control signal rising speeding circuit 36 will be described with reference to FIG. 9. The control signal rising speeding circuit 36 is a rectifier / buffer circuit which receives an output from the power amplifier 12 as an input signal. 38
And a differentiation circuit 40 to which an output signal of the rectification / buffer circuit 38 is inputted, and an ideal diode circuit 42 to which an output signal of the differentiation circuit 40 is inputted. It is input to the DC converter control signal generation circuit 30.

FIG. 10 shows a detailed circuit configuration of the control signal rising speed-up circuit 36 for realizing the rectifier / buffer circuit 38, the differentiating circuit 40, and the ideal diode circuit 42.

Here, FIG. 11 shows voltage waveforms at various parts of the control signal rising speeding circuit 36 shown in FIG. 10, and the operation of the control signal rising speeding circuit 36 will be described with reference to FIG. Will be described.

First, the control signal rising speeding circuit 36
The output from the power amplifier 12 at the point A is given as an input signal to the rectification / buffer circuit 38, and its waveform is, for example, a sine wave.

The signal at the point A is half-wave rectified by the diode 38a, which is a rectifier circuit of the rectifier / buffer circuit 38. Further, the level is shifted to minus by the resistor 38b, and the signal of the voltage waveform shown at the point B is obtained. Becomes
The signal of the voltage waveform shown at the point B is inverted by the buffer 38c and becomes a signal of the voltage waveform shown at the point C which protrudes downward (minus direction).

The signal of the voltage waveform shown at the point C thus obtained is differentiated by the differentiating circuit 40, and as shown at the point D, the falling portion of the voltage waveform including the edge portion becomes steep and the signal at the point A A signal having a voltage waveform falling at a time slightly earlier than the rising of the voltage waveform shown is obtained.

The signal of the voltage waveform shown at the point D is rectified by the ideal diode circuit 42 without loss of the diode, and unnecessary components are cut and inverted. The voltage at the point E is like a rising portion of a sine wave. A signal having a waveform that rises sharply and rises at a time slightly earlier than the rise of the voltage waveform shown at point A is obtained.

Then, as described above, the DC-DC converter control signal generation circuit 30 generates the voltage waveform signal shown at the point E and the voltage waveform signal (a signal obtained by rectifying the input signal) shown at the point A, which are obtained as described above. Are added and synthesized to generate an output signal. Therefore, as described above, from the DC-DC converter control signal generation circuit 30, the waveform protrudes downward (negative direction), and the voltage at the fall is sharply reduced, and the fall is sharp, and , A signal having a voltage waveform falling at a time slightly earlier than the rising of the voltage waveform shown at point A is obtained.

As a result, the rising waveform of the voltage waveform of the output signal as the output of the DC-DC converter is improved, and the steep rising of the input signal having a high frequency (high frequency) and a large amplitude (large output) is achieved. Also, there is no delay, and the followability to a steep rising of an input signal having a high frequency (high frequency) and a large amplitude (large output) is improved.

[0053]

Since the present invention is configured as described above, the rising waveform of the voltage waveform of the output of the DC-DC converter can be improved, and the high frequency (high frequency) and large amplitude (large output) can be obtained. There is no delay even for a steep rising of the input signal, and an excellent effect that the followability to a steep rising of an input signal having a high frequency (high frequency) and a large amplitude (large output) can be improved. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional amplifier circuit.

FIG. 2 is a block diagram of a conventional DC-DC converter.

FIG. 3 is a voltage waveform diagram of each part of a conventional DC-DC converter (FIG. 2).

FIG. 4 is a voltage waveform diagram of each part of the conventional amplifier circuit (FIG. 1) when a large amplitude signal having a frequency of 1 kHz is input.

FIG. 5 is a voltage waveform diagram of each part of the conventional amplifier circuit (FIG. 1) when a large amplitude signal having a frequency of 10 kHz is input.

FIG. 6 is a block diagram illustrating an example of an embodiment of a DC-DC converter according to the present invention.

7 is a voltage waveform diagram of each part of the DC-DC converter (FIG. 6) according to the present invention when a signal having a frequency of 5 kHz is input.

8 is a voltage waveform diagram of each part of the DC-DC converter (FIG. 6) according to the present invention when a signal having a frequency of 1 kHz is input.

FIG. 9 is a detailed block diagram of a main part of the DC-DC converter (FIG. 6) according to the present invention.

FIG. 10 is a detailed circuit diagram of a control signal rising speeding circuit.

FIG. 11 is a voltage waveform diagram of each part of the control signal rising speeding circuit.

[Explanation of symbols]

Reference Signs List 10 signal source 12 power amplifier 14 voltage amplifying circuit 16, 18 power transistor 20 speaker 22 power supply (+ B) 24 + side power supply DC-DC converter 26 power supply (-B) 28-side power supply DC-DC converter 30 DC-DC Converter control signal generation circuit 32 DC-DC converter IC 34 DC-DC converter output circuit 36 Control signal rise speed-up circuit 38 Rectification / buffer circuit 38a Diode 38b Resistance 40 Differentiator circuit 42 Ideal diode circuit

Continued on the front page F term (reference) 5H730 AA04 AS00 BB13 BB57 DD04 FD01 FG05 5J092 AA02 AA18 AA41 CA36 CA65 FA03 FA18 GR02 GR05 HA02 HA08 HA09 HA19 HA25 HA29 HA33 HA39 KA01 KA11 KA30 KA48 KA49 KA51 TA20 MA05 SA05

Claims (4)

[Claims] 1. A DC-DC converter control signal generation circuit that rectifies an input signal and then shifts and outputs DC, and a DC that generates a switching signal based on an output signal of the DC-DC converter control signal generation circuit. A DC-DC converter circuit, and a DC-DC converter output circuit that generates and outputs an output signal for outputting to the outside based on the switching signal. A control signal rising speeding circuit that generates a signal having a rising portion-like waveform and a waveform that rises steeply and supplies the signal to the DC-DC converter control signal generating circuit; The signal generation circuit receives a signal obtained by rectifying the input signal and the control signal rising speed-up circuit. Signal and the DC-DC converter from the additive synthesis and outputs to shift the DC to. 2. A waveform of a signal supplied from the control signal rising speeding circuit to the DC-DC converter control signal generating circuit is a waveform rising at a time slightly earlier than the rising of the waveform of the input signal. DC converter. 3. The DC-DC converter according to claim 1, wherein the control signal rising and speeding-up circuit includes a rectifier / buffer circuit for half-wave rectifying the input signal and outputting the input signal, A DC-DC converter having a differentiating circuit for differentiating the output and outputting the same, and an ideal diode circuit for rectifying the output from the differentiating circuit without loss and outputting the rectified output to the DC-DC converter control signal generating circuit. 4. The DC-DC converter according to claim 3, wherein the rectifier / buffer circuit rectifies the input signal by half-wave rectification, and outputs the input signal half-wave rectified by the rectifier circuit. DC-DC having a buffer circuit for performing the operation, and a resistor inserted between the rectifier circuit and the buffer circuit to shift the level of the input signal to the negative side.
converter.