KR100401428B1 - Apparatus for reducing noise in a class d amplifier - Google Patents

Abstract

The apparatus for removing noise of a class-D amplifier according to the present invention includes a comparison means for generating an operation control signal for controlling the operation of the amplifier according to a comparison result of the broadcast signal output from the tuner with a preset reference value, and broadcasting channel selection. A switching means for outputting a signal for turning off the amplifier to a sleep terminal of the amplifier in accordance with a tuning signal input from a switch, and for outputting a signal for controlling the amplifier to the sleep terminal in accordance with an operation control signal output from the comparing means; Include.

As described above, the present invention is capable of removing noise generated at the time of automatic tuning of the broadcast frequency by turning off the class D amplifier according to the tuning signal generated by the switching operation of the user's broadcasting tuning switch while listening to the broadcasting. There is.

In addition, the present invention has the effect of eliminating the high-speed switching noise of the digital amplifier generated during the automatic tuning of the broadcast tuning switch.

Description

Noise canceling device of class D amplifier {APPARATUS FOR REDUCING NOISE IN A CLASS D AMPLIFIER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital amplifier for broadcast reception, and more particularly, to a noise canceling device of a class D amplifier for reducing noise of a digital amplifier generated during automatic tuning of a broadcast channel.

In general, Class-D amplifiers use pulse-width modulation and are more efficient than analog amplifiers. In addition, class D amplifiers, unlike ordinary amplifiers (Class A, Class B, etc.), operate only in the switching mode of the transistor, resulting in minimal power loss.

However, if the sound equipment is implemented using the low loss efficiency of the class D amplifier, the class D amplifier has analog and digital circuits on one printed circuit board (PCB), and thus, peripheral devices and other An electromagnetic interface (EMI) large enough to cause reception radio interference will be generated.

EMI generated during the conversion of digital signals to pulse-width modulated signals has a significant effect on peripherals and other received radio waves, which can interfere with the normal operation of the equipment.In other words, digital Class-D amplifiers are analog amplifiers. Compared with the advantages of high efficiency, the cooling device is very small, and although the power supply capacity is small, the EMI characteristic generated by the fast switching operation is bad.

Due to the EMI generated during the pulse width modulation of the class D amplifier, it is difficult to develop a product using the class D amplifier.

An object of the present invention is to solve such a problem of the prior art, the operation of the digital amplifier during the broadcast search process because the receiving device is interrupted by accurate broadcast frequency tuning during the broadcast search due to the noise caused by the high-speed switching of the digital amplifier We want to provide a noise canceling device for Class D amplifiers that temporarily stops the digital amplifier to eliminate EMI emissions.

In order to achieve the above object, the present invention provides a tuner for outputting a signal according to broadcast and broadcast frequency search, a broadcast tuning switch for tuning the frequency of the broadcast voice signal, and a broadcast voice signal received by the tuner. An apparatus for removing noise from a broadcast receiver, comprising: comparing means for generating an operation control signal for controlling the operation of the amplifier according to a comparison result of a broadcast signal output from the tuner with a preset reference value; And outputting a signal for turning off the amplifier to a sleep terminal of the amplifier according to a tuning signal input from the broadcast tuning switch, and controlling the amplifier to the sleep terminal according to an operation control signal output from the comparing means. Switching means for outputting a signal.

1 is a block diagram showing an operation control apparatus of a class D amplifier according to the present invention;

2 is a flowchart illustrating an operation control process of a class D amplifier according to the present invention.

<Description of the code | symbol about the principal part of drawing>

100: broadcast receiver 110: tuner

120: broadcast tuning switch 200: amplifier noise canceller

210: comparison means 211: signal converter

212: comparator 220: inverter

300: amplifier

There may be a plurality of embodiments of the present invention, and a preferred embodiment will be described in detail below with reference to the accompanying drawings. Those skilled in the art will be able to better understand the objects, features and advantages of the present invention through this embodiment.

1 is a block diagram showing an operation control apparatus of a class D amplifier according to the present invention.

As shown therein, the operation control apparatus of the class D amplifier includes a broadcast receiver 100 including a tuner 110 and a broadcast tuning switch 120, a comparison means 210, an inverter 220, and a flip flop 230. Class D amplifier noise canceling device 200, including a class D amplifier 300, and a speaker (SP).

The tuner 110 of the broadcast receiver 100 tunes to a signal of a specific channel selected by a user, and outputs an input broadcast voice signal to the class-D amplifier 300, and broadcast broadcasting by a switching operation of the broadcast channel selection switch 120. Outputs a reduced broadcast voice signal (ie, a search signal) to the class D amplifier noise canceller 200. In this case, the search signal according to the broadcast frequency search may be a signal extracted from the RF receiver of the tuner 110 or the IF receiver of the tuner 110.

The broadcast channel selection switch 120 checks whether the broadcast automatic channel switching operation is performed by the user and outputs the broadcast channel selection signal to the class-D amplifier noise removing device 200 when the broadcast channel selection switch 120 is operated.

The class D amplifier 300 has a sleep terminal connected to the output terminal of the flip flop 230 and receiving an output signal of the flip flop 230, and the sleep terminal is turned on or off according to the output signal of the flip flop 230. It is done.

When the sleep terminal of the class D amplifier 300 is on, the class D amplifier 300 is in a sleep mode in which no switching operation is performed, and when the sleep terminal of the class D amplifier 300 is off, the class D amplifier ( 300 is an operation mode state in which the broadcasting signal input from the signal tuner 110 input to the class D amplifier 300 is amplified and output to the speaker SP through a switching operation.

The inverter 220 is a means for inverting a tuning signal generated by the broadcasting channel switching operation of the broadcasting channel switching switch 120. The inverter 220 generates a low signal generated when the broadcasting channel switching switch 120 operates. High) is converted into a signal and output to the clear stage of the flip-flop 230, and the output signal of the flip-flop 230 (when broadcasting) by the signal input to the clear stage of the flip-flop 230. By converting the signal to a low signal to turn on the sleep terminal of the class D amplifier 300, the class D amplifier 300 is switched to the sleep mode.

The comparison means 210 generates an operation control signal for controlling the operation of the class D amplifier 300 according to a result of comparing the broadcast signal output from the tuner 110 with a preset reference value, and the configuration thereof includes a signal converter ( 211) and a comparator 212.

The search signal output from the tuner 110 is converted by the signal converter 211 according to the switching operation of the broadcast tuning switch 120, and the converted signal is provided to the flip-flop 230 through the comparator 212. .

When the tuner 110 searches for a new broadcast frequency according to the switching operation of the broadcast tuning switch 120, the signal converter 211 receives a search signal output from the tuner 110 and converts it into a signal having an effective value. It sends out to the comparator 212. The signal converter 211 outputs a low signal having an effective value when a search signal (ie, a signal smaller than a reference value) is output from the tuner 110, and the signal output from the tuner 110 is a broadcast signal. In the case of (signal larger than reference value), a high signal having an effective value is output.

The comparator 212 converts the output of the comparator 212 from low to high when the signal input from the signal converter 211 is greater than the preset input voltage Vth, and outputs the signal converter 211. If the signal input from the () is less than the voltage (Vth), the output of the comparator 212 is converted from High to Low and output.

At this time, the signal output from the comparator 212 is input to the clock terminal of the flip-flop 230 connected to the output terminal of the comparator 212, the output signal of the flip-flop 230 is converted according to the input signal It is provided to the sleep terminal of the class D amplifier (300). The sleep terminal is controlled on / off by the output signal of the flip flop 230, and thus the operation of the class D amplifier 300 is controlled.

The flip-flop 230 is a switching means for determining the operation of the class D amplifier 300, receives the tuning signal output from the broadcast tuning switch 120 converted through the inverter 220 to the clear stage, the comparator ( It is composed of a D-flip flop that receives the operation control signal of the class D amplifier 300 output from 212 as a clock signal and varies the output signal of the flip flop 230.

The signal output from the output terminal Q of the flip-flop 230 is high only when the operation control signal of the class-D amplifier 300 output from the comparator 212 is converted from low to high. The D-class amplifier 300 switches again by a high signal output from the output terminal Q of the flip-flop 230 to amplify the signal input to the D-class amplifier 300 so that the speaker Output to (SP). In addition, except in the case where the operation control signal of the class-D amplifier 300 output from the comparator 212 is converted from low to high, the output signal from the output terminal Q of the flip-flop 230 is output. By maintaining the low signal, the class D amplifier 300 maintains a sleep mode in which no switching operation is performed. In the sleep mode, the class D amplifier 300 is turned off and does not output any signal through the speaker SP.

Therefore, the broadcast tuning device can tune to a new broadcast frequency at the time of broadcast frequency tuning (ie, when the broadcast tuning switch 120 generates a low signal) without external disturbance (no noise).

The operation control process of the class D amplifier having the above configuration is as follows.

2 is a flowchart illustrating an operation control process of a class D amplifier according to the present invention.

As shown therein, the broadcast voice signal output by the tuner 110 of the broadcast receiver 100 is amplified by a constant gain value by the class D amplifier 300 and output to the speaker SP (S201).

The broadcast tuning switch 120 determines whether the broadcast tuning switch 120 is operated by the user (whether the user has pressed the broadcast tuning switch 120) (S202).

As a result of the determination in step 202, when the broadcast tuning switch 120 does not perform a switching operation according to the broadcast tuning by the user (that is, when the user does not press the broadcast tuning switch 120), the process returns to step 201. The signal is continuously amplified and output according to the true broadcast frequency.

When a user presses the broadcasting tuning switch 120 to tune to another broadcasting frequency, the tuning signal (low signal) generated by the switching operation of the broadcasting tuning switch 120 is inverted to a high signal by the inverter 230. It is input to the clear terminal of the flip-flop 230, the sleep terminal of the class D amplifier 300 is turned on by the signal input to the flip-flop 230 to convert the class-D amplifier 300 into the sleep mode to convert the class-D amplifier The operation of 300 is turned off (S203, S204).

The broadcast frequency search signal (that is, the broadcast voice signal in the tuned state) output from the tuner 110 at each moment while tuning the broadcast frequency by the operation of the broadcast tuning switch 120 is input to the signal converter 211 to provide an effective value. It is converted into a signal having (S205).

The comparator 212 compares the output signal of the tuner 110 converted by the signal converter 211 with a preset voltage Vth (or current). In other words, it is determined whether or not other broadcasting frequency tuning is completed (S206).

As a result of the determination in step 206, if the output signal of the tuner 110, which has been changed to the effective value by the signal converter 211, is input to the comparator 212 in the form of a signal smaller than the reference value (if it is not yet able to tune to another broadcast frequency), the comparator The output of 212 continues to be low, and thus the output of flip-flop 230 continues to be low, so the operation of class D amplifier 300 is slipped by the signal output from flip-flop 230. Keep the mode. In other words, the process returns to step 205 to perform broadcast frequency tuning.

When the output signal of the tuner 110 converted to the effective value by the signal converter 211 is input to the comparator 212 in a form larger than the reference value (when tuning of another broadcast frequency is completed), the output of the comparator 212 is low. From low to high, the output of the flip-flop 230 is changed to high to turn off the sleep terminal of the class D amplifier 300 to switch the class D amplifier 300 (that is, Switch to the operation mode) (S207, S208, S209).

The class D amplifier 300 operates and amplifies the broadcast voice signal having the tuned frequency and outputs it through the speaker SP (S210).

As described above, the present invention is to turn off the class D amplifier according to the tuning signal generated by the switching operation of the user's broadcasting tuning switch while listening to the broadcasting, and to turn on the class D amplifier when the tuning is completed, There is an effect of removing noise generated at the time of automatic tuning. The present invention also has the effect of removing high-speed switching noise of a digital amplifier generated at the time of automatic tuning of a broadcast tuning switch.

Claims (3)

A broadcast receiving amplifier noise canceller comprising a tuner for outputting a signal according to a broadcast and broadcast frequency search, a broadcast tuning switch for tuning the frequency of the broadcast voice signal, and an amplifier for outputting a broadcast voice signal received by the tuner. To Comparison means for generating an operation control signal for controlling the operation of the amplifier according to a comparison result of the broadcast signal output from the tuner with a preset reference value; A signal for outputting a signal for turning off the amplifier to a sleep terminal of the amplifier according to a tuning signal input from the broadcast tuning switch, and for controlling the amplifier to the sleep terminal according to an operation control signal output from the comparing means Noise canceling device of a class D amplifier comprising a switching means for outputting. The method of claim 1, The switching means, And a flip-flop for receiving the channel selection signal at a clear stage and receiving the operation control signal as a clock signal and varying and outputting the signal. The method of claim 1, The comparison means, Signal conversion means for converting a signal output from the tuner into an effective value, And a comparator for outputting the operation control signal according to a comparison result of the signal converted by the signal conversion means with a preset reference value.