JPS61292407A - Acoustic device and amplifying method - Google Patents

Abstract

PURPOSE:To obtain an acoustic device having both the excellent efficiency of a class D amplifier and the excellent resolution of an analog power amplifier by separating an input signal into a large amplitude element and a small amplitude element, applying pulse amplification to the large amplitude element and amplifying analogically the small amplitude element and adding both the elements in the process of amplification. CONSTITUTION:An input signal 5 can be a PCM signal or an analog signal. The class D amplifier section 2 has bad resolution. Then the input signal 5 is decomposed into the large amplitude element and the small amplitude element. This is performed by an amplitude separation section 1. The large amplitude element not so much requiring the resolution is amplified by the class S amplifier section 2 and the small amplitude element is amplified analogically by an analog amplifier section 3. Then the large amplitude element and the small amplitude element are added by an adder section 4 to form the original sound. Thus, the large amplitude element requiring large current amplification is amplified by the class D amplifier with excellent efficiency and the small amplitude element requiring the resolution is amplified by an analog amplifier so as to utilize both the advantages.

Description

DETAILED DESCRIPTION OF THE INVENTION The signal is converted into a width modulated or pulse frequency modulated digital signal, sufficiently amplified, and passed through a low pass filter if necessary to drive a speaker.

Let's take pulse width modulation as an example. Assuming that the highest reproduction frequency is 20 KHz, sampling must be performed at 40 KHz or higher. That is, the pulse width is from O to 25
Changes with tfsEct. Now, if the pulse width is controlled by 12-pit expression, the pulse resolution needs to be 6nSEC. In other words, a pulse with a pulse width of 6nSEC must be amplified. However, K that drives the speaker requires an amplifier circuit that allows a large current to flow, and it is impossible to obtain such resolution. The present invention was invented to solve this problem.

Next, the present invention will be explained in detail.

Figure 1 shows the basic configuration. The input signal 5 may be considered to be a PCM signal or an analog signal. Here, the D-class amplifier part 2 has a poor ability to solve problems. Therefore, the input signal 5 is decomposed into large amplitude elements and small amplitude elements.

This is performed by the amplitude separator 1. Thereafter, large amplitude elements that do not require high resolution are amplified by the 0222771 section 2, and small amplitude elements are amplified in an analog manner by the analog power amplifier section 3. Thereafter, the adder 4 adds the large amplitude element and the small amplitude @ element to obtain the original sound. By doing this, large-amplitude elements that require larger current amplification than K are amplified by efficient class D amplifiers, and multi-amplitude elements that require resolution are amplified by analog power amplifiers, so it has the best of both worlds. becomes.

Next, each part will be explained.

An embodiment of the amplitude separator 1 is shown in FIG. In this case the input signal is a PCM serial signal. In addition to the pulse train of the input signal, a clock that indicates the pulse read timing and a synchronization signal that indicates the data delimiter are required. In this example, the input signal 6 as shown in FIG. The discussion will proceed assuming that a clock 7 and a synchronization signal 8 are input. Also, the data length is 1
In 6 bits, (8001)H to (FFFF)H represent positive voltage, and (7FFF)H to (0000)H represent negative voltage. Therefore, the maximum negative voltage is (0000)H, and the maximum positive voltage 1 ((FFFF
) H-t' is present, and represents (s o o o ) aka ov. Here, ()H indicates hexadecimal representation. Input signal 9 is set in shift register 12 by clock 10.

Here, the lower number bits 1 of the parallel output of the shift register 12
4 is a small amplitude element and is added to the D/A converter 13.

Furthermore, the most significant bit 16 of the output of the shift register 12 is applied to the D/A converter 13 as a sign bit. When the synchronization bit 11 is input, the previous data is completely set in the shift register 12, and this timing is used to determine the analog signal level. This signal is output to the analog power amplifier section 3 through the volume 15.

The remaining bit 17 of the shift register 12 is output to the 0221771 section 2 as a large amplitude element. Most significant bit 16
is also output as a bit that determines the sign.

In the previous example, input signal 5 was PCM.

Next, FIG. 4 shows an example in which the input signal 5 is an analog signal. Input 'signal 29 is connected to A/D converter 18 link 6
a! Rehalus: Add to PliF'. This pulse 29 should be 40KHz in order to make the maximum reproduction frequency 20KHz.
The above is necessary. Furthermore, since the output of the A/D converter 18 is set to (8000)H when the input signal 19 is OV, it is necessary to apply an offset voltage to the A/D converter 18. A
The most significant biratra polarity bit 25 of the output of the /D converter 18 is set, the lower several pictographs 24 are set as small amplitude elements, and the remaining bits 23 are set as large amplitude elements. The small amplitude element 24 is D/A
The converter 20 converts the analog signal A into an output 22 to the analog power amplifier section 3 again. Also, the large amplitude element 23 becomes the output 21 to the 0221771 part 2. Next, regarding the 0221771 part 2, Kiriyuki will discuss. In the example of the amplitude separation section 1, the output to the 0221771 section 2 is binary data. Therefore, it is sufficient to convert this binary data f into pulse width and change the polarity of the pulse using the polarity bit.

Next, the analog power amplifier section 3 will be described.

The analog power amplifier section 3 has a small output, so it is best to fully utilize it, such as a car stereo IC.

Next, the addition section 4 will be described.

There are three types of additions:

(b) Add in a sound field equipped with two speakers.

(b) If the speaker is equipped with two voice coils, the sum will be added inside the speaker.

(c) Add electrically.

As described above, according to the present invention, it is possible to provide an audio device that has both the high efficiency of a D class amplifier and the high resolution of an analog power amplifier.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram. Figures 1iIJ2 are data examples when the input signal is PCM. FIG. 3 is a circuit example of the amplitude separation section. FIG. 4 is a circuit example of the amplitude separation section. 1 is an amplitude separation section, 2 is a D class amplifier section, 3 is an analog power amplifier section, 4 is an addition section, 5 is an input signal, 6 is an input signal,
7 is a clock, 8 is a synchronization signal, 9 is an input signal, 10 is a clock, 11 is a synchronization signal,
12 is a shift register, 13 is a D/A converter, 14
are the lower several bits (small amplitude elements), 15 is the polyneem, 16 is the most significant bit, 17 is the large amplitude element bit, 18 is the output to the analog power amplifier section, 19 is the A/D
converter, 20 is a D/A converter, 21 is an output to the D class amplifier section, 22 is an output to the analog power amplifier section, 23 is a large amplitude element bit, 24 is a small amplitude element bit, 25 is the most significant bit, 26 is a polyneem, 27 is a delay circuit, 28 is output as a read clock to the D class amplifier section, '$111゜. 3°72 figure

Claims (2)

[Claims] (1) Amplification characterized by separating an input signal into large-amplitude elements and small-amplitude elements, pulse-amplifying the large-amplitude elements, amplifying the small-amplitude elements in an analog manner, and adding the above-mentioned elements afterwards or during the amplification process. Method. (2) means for separating an input signal into large amplitude elements and small amplitude elements; a D class amplifier that amplifies the large amplitude elements; an analog power amplifier that amplifies the small amplitude elements; the output of the D class amplifier; and the analog power amplifier. An acoustic device comprising: an output of; and means for applying.