CN101325404B - Frequency-hopping carrier generator - Google Patents
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- CN101325404B CN101325404B CN200710110936XA CN200710110936A CN101325404B CN 101325404 B CN101325404 B CN 101325404B CN 200710110936X A CN200710110936X A CN 200710110936XA CN 200710110936 A CN200710110936 A CN 200710110936A CN 101325404 B CN101325404 B CN 101325404B
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Abstract
The invention discloses a frequency hopping carrier generator, comprising a current source for generating a first current, output to a ramp voltage generator, which outputs the ramp voltage. The output ends of the ramp voltage generator are respectively connected with a capacitance, a voltage sense and direction controller, and a pulse width modulating module, which receives the audio input signal, after the voltage sense and direction controller receives the ramp voltage, synchronously output the control signal to the ramp voltage generate and a counter connected with a digital control current source. According to the value of the counter, the digital control current source outputs a second current to the ramp voltage generator. The input end of the switch power amplifier receives the signal from the pulse width modulating module and modulates the audio input signal to output D-kind signal.
Description
Technical field
The present invention relates to frequency-hopping carrier generator, particularly relate to and a kind ofly do not have low pass filter and produce the frequency-hopping carrier generator that variation frequency reduces the EMI peak value according to first electric current and second electric current.
Background technology
D class (digital audio power) amplifier is a kind ofly will import simulated audio signal or PCM digital information converts PWM (pulse width modulation) or PDM (impulse density modulation) isopulse signal to, remove to control the audio-frequency power amplifier of high-power switch device on/off then with the pulse signal of PWM or PDM, be also referred to as switch power amplifier, it has high efficiency outstanding advantage.Amplification of D class or digital amplifier form circuit, switch power circuit (semibridge system and full-bridge type) and low pass filter four parts such as (LC) by input signal treatment circuit, switching signal and form.The D class A amplifier A is to utilize the conversion switch circuit of high frequency to come audio signal.Its characteristic is as follows, 1. has very high efficient, can reach more than 85% usually.2。Volume is little, can save very big space than the amplifying circuit of analogy.3。There is not the noise of splitting during switch.
The shortcoming of traditional D class A amplifier A is to need to use low pass filter, owing to use low pass filter can increase cost and the excessive circuit design that is unfavorable for integral body of its volume, so advanced manufacturer just proposes not have the D power-like amplifier of low pass filter.The D class A amplifier A of no low pass filter can be with reference to No. 6545533, the United States Patent (USP) of disclosed Texas Instruments on the 8th April in 2003, and this kind D class A amplifier A uses mess code (PSEDUO NOISE) generator.But because the mess code generator is asynchronous with the PWM carrier wave, the difference frequency of these two signals will cause interference to audio signal.Because the signal of mess code generator is as a random signal, so its difference frequency interference signal can't reduce its annoyance level with specific circuit also as a random disturbances signal.
Another kind of D class A amplifier A can be a kind of D class A amplifier As that do not have low pass filter that MAXIM company is released with reference to No. 6847257 these patents of laid-open U.S. Patents on January 25th, 2005, and it provides fixed frequency (FFM) pattern and spread-spectrum (SSM) pattern.The reason that this type of technology meets the requirement of EMI radiation levels is to increase a common mode pulse in original signal, and spread spectrum mode has reduced the EMI radiation that modulating frequency produces, and still can meet the requirement of FCC EMI radiation levels exactly when not adding the LC filter.But this invention produces at random in the generation of frequency of amendment.As shown in Figure 1, the spectrogram of the traditional D class A amplifier A wherein peak value of energy is-4db, and its high-frequency harmonic (harmonics) is-20db.
Summary of the invention
Main order of the present invention provides a kind of frequency-hopping carrier generator, can be applicable to be used for saving cost, and still can meet the requirement of FCC EMI radiation levels on a kind of D class A amplifier A that does not have a low pass filter.
Another object of the present invention provides a kind of frequency-hopping carrier generator, the generation of its frequency of amendment is synchronous, when detecting voltage device detecting voltage is higher than first magnitude of voltage, this detecting voltage and direction controller can produce one and control signal to ramp generating circuit and make this electric capacity become discharge condition by charged state to change the sense of current, and when this detecting voltage device detecting voltage was lower than second magnitude of voltage, this detecting voltage and direction controller can produce one and control signal to ramp generating circuit and make this electric capacity become charged state by discharge condition to change the sense of current.So because to charge and discharge power supply is that a current source charge-discharge characteristic is a straight line, the voltage of electric capacity promptly discharges and recharges with linear mode between first voltage and second voltage and exports oblique wave (ramp) like this.
The invention provides a kind of frequency-hopping carrier generator, comprise current source, current source is in order to produce first electric current; First electric current may be output to a ramp voltage generator, by ramp voltage generator (ramp generator) and the electric capacity output ramp voltage that is connected.The output of ramp voltage generator connects detecting voltage and direction controller and pulse width modulation module respectively, and this pulse width modulation module can receive audio input signal in addition, and after this detecting voltage and direction controller receive ramp voltage, output control signals to this ramp voltage generator and counter synchronously, counter is connected with digital control current source, according to the value of this counter, this digital control current source is exported second electric current to this ramp voltage generator.This second electric current promptly compiles to change the ramp voltage generator with first electric current it is connected the discharging and recharging slope of electric capacity and changes carrier frequency.In other words, the frequency of carrier wave changes along with the content of counter.Because control signal generation when changing into discharge or discharge to change into charging by charging, and control signal is directly changed the content of counter and is controlled the size of charging or discharging current, reaches synchronous purpose so the change of the size of charging or discharging current takes place simultaneously with the change that discharges and recharges direction.
Frequency-hopping carrier generator of the present invention can be applicable on the D class A amplifier A of no low pass filter, and still can meet the requirement of FCC EMI radiation levels, and the generation of variation frequency of the present invention is synchronous, so can avoid difference frequency to disturb.
Description of drawings
Fig. 1 is the EMI datagram of prior art;
Fig. 2 is the circuit framework block diagram of embodiment of the present invention;
Fig. 3 is the EMI datagram of embodiment of the present invention.
The critical piece symbol description is as follows:
12 ramp voltage generators
14 current sources
16 electric capacity
18 detecting voltages and direction controller
20 counters
22 digital control current sources
24 pulse width modulation modules
26 switch power amplifiers
Embodiment
For describing the present invention in detail, please refer to Fig. 2 and Fig. 3.The frequency-hopping carrier generator of the embodiment of the invention includes ramp voltage generator 12, to produce different variation frequency.
Frequency-hopping carrier generator comprises the current source 14 that produces first electric current, after current source 14 produces first electric current, export first electric current receiving terminal of a ramp voltage generator 12 to, ramp voltage generator 12 cooperates electric capacity 16 with the output ramp voltage after receiving these first electric currents.As shown in Figure 2, the output of ramp voltage generator 12 connects electric capacity 16 (definite value), detecting voltage and direction controller 18, pulse width modulation (PWM) module 24 respectively.When detecting voltage and direction controller 18 sent the charge or discharge direction of control signal change electric capacity 16, the value of counter 20 also was updated simultaneously.
After detecting voltage and direction controller 18 receive ramp voltage, output control signals to this ramp voltage generator 12 and counter 20 synchronously.Wherein counter 20 is a gray code counter (Gray CodeCounter).Counter 20 is connected with digital control current source 22, value according to counter 20, output second electric currents are to ramp voltage generator 12 synchronously for digital control current source 22, and this second electric current and first electric current compile and become the charge or discharge electric current and discharge and recharge slope or synchronous change oblique wave frequency with synchronous change.Pulse width modulation module 24 can receive audio input signal in addition, the output signal of pulse width modulation module 24 be a PM signal (PWM) its may be output to the input of switch power amplifier 26, again by switch power amplifier 26 output D class signals.
Because its output code of gray code counter once only changes a position (bit), its other counter of exchange noise ratio is low, and present embodiment can produce 2 with gray code counter as the gray code counter 20 of 20, one N positions of counter
NDifferent values reduces the peak value of EMI, and the formula that reduces peak value is:
10log?1/2
N＝-10log2
N＝-10Nlog2＝-3Ndb
Therefore, as present embodiment with one 4 gray code counter 20 as example, can make EMI peak value reduction-12db in theory.Please refer to Fig. 3, compared to Fig. 1, the energy peak of Fig. 3 for-12db and its high-frequency harmonic (harmonics) maintain-below the 30db, its improvement degree is between 8～10db.The D power-like amplifier of no low pass filter is by a larger margin reduction EMI if desired, can increase the position of gray code counter.No matter what of position, the output code of gray code counter once only changes a position, can not increase along with the increase of position so it exchanges noise.Other digital counting device such as binary counter (Binary Counter), decade counter (BCD Counter) or mess code generator all can't reach the purpose of the low exchange noise of one of little another change of circuit.
The generation of the variation frequency of the embodiment of the invention is synchronous.The mode that changes is when detecting voltage device detecting voltage is higher than first magnitude of voltage, this detecting voltage and direction controller 18 can produce a control signal makes this electric capacity 16 become discharge condition by charged state, when this detecting voltage device detecting voltage was lower than second magnitude of voltage, this detecting voltage and direction controller 18 can produce a control signal made this electric capacity 16 become charged state by discharge condition.From the above, second size of current also will be revised the slope that discharges and recharges with synchronous change thereupon when electric capacity 16 changes charging and discharging state.
The above is the preferred embodiments of the present invention only, is not to be used for limiting scope of the invention process.So all should be included in the claim of the present invention according to variation or modification that the described shape of the present patent application scope, structure, feature and spirit are done.
Claims (8)
1. a frequency-hopping carrier generator is characterized in that, comprising:
Counter;
Current source produces first electric current;
The ramp voltage generator receives described first electric current, and the output ramp voltage;
Electric capacity connects the output of described ramp voltage generator;
Detecting voltage and direction controller connect described ramp voltage generator output;
Pulse width modulation PWM module, connect described ramp voltage generator output, and this pulse width modulation PWM module also can receive audio input signal, and after described detecting voltage and direction controller received ramp voltage, the voltage of output control synchronously was to ramp voltage generator and described counter;
Digital control current source, connect described counter, and according to the value of counter, export second electric current to described ramp voltage generator, described detecting voltage and direction controller are detected the voltage of described ramp voltage generator, to produce the charging and discharging state that a control signal changes described electric capacity, first electric current and second electric current compile to produce the charge or discharge electric current, and when electric capacity changes charging and discharging state, the size of this second electric current also will be revised thereupon synchronously, also will be revised synchronously by the size of the charging and discharging currents that first electric current and second electric current compiled again thereupon;
Switch power amplifier, its input receives the signal from this pulse width modulation PWM module.
2. frequency-hopping carrier generator as claimed in claim 1, it is characterized in that, when the voltage that wherein said detecting voltage and direction controller are detected described ramp voltage generator was higher than first magnitude of voltage, described detecting voltage and direction controller can produce a control signal made the state of this electric capacity become discharge condition by charged state.
3. frequency-hopping carrier generator as claimed in claim 1, it is characterized in that, when the voltage that wherein said detecting voltage and direction controller are detected described ramp voltage generator was lower than second magnitude of voltage, described detecting voltage and direction controller can produce a control signal made the state of this electric capacity become charged state by discharge condition.
4. frequency-hopping carrier generator as claimed in claim 1 is characterized in that, when wherein said detecting voltage and direction controller sent control signal and change the charging and discharging state of this electric capacity, the value of this counter was updated simultaneously.
5. frequency-hopping carrier generator as claimed in claim 1 is characterized in that described counter is a gray code counter.
6. frequency-hopping carrier generator as claimed in claim 1 is characterized in that, the ramp voltage generator produces ramp voltage according to the charging and discharging currents that compiles with the electric capacity that is connected.
7. frequency-hopping carrier generator as claimed in claim 1 is characterized in that, described pulse width modulation PWM module is carried out modulation with audio input signal and ramp voltage.
8. frequency-hopping carrier generator as claimed in claim 1 is characterized in that, wherein this power amplifier receives the signal from this pulse width modulation PWM module, and audio input signal is carried out modulation with output D class signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710110936XA CN101325404B (en) | 2007-06-11 | 2007-06-11 | Frequency-hopping carrier generator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710110936XA CN101325404B (en) | 2007-06-11 | 2007-06-11 | Frequency-hopping carrier generator |
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| Publication Number | Publication Date |
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| CN101325404A CN101325404A (en) | 2008-12-17 |
| CN101325404B true CN101325404B (en) | 2010-06-16 |
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| CN200710110936XA Expired - Fee Related CN101325404B (en) | 2007-06-11 | 2007-06-11 | Frequency-hopping carrier generator |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108768309A (en) * | 2018-06-11 | 2018-11-06 | 聚辰半导体(上海)有限公司 | Audio-frequency power amplifier and its transient noise suppressing method |
| CN112511159B (en) * | 2020-11-24 | 2024-08-06 | 深圳伊凡微电子有限公司 | Electromagnetic compatibility frequency source of PD fast charge PWM chip |
| CN112491001B (en) * | 2020-12-04 | 2022-08-23 | 国创移动能源创新中心(江苏)有限公司 | Filtering-free signal acquisition method and system and leakage protection device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4668919A (en) * | 1986-02-19 | 1987-05-26 | Advanced Micro Devices, Inc. | High speed operational amplifier |
| US5812028A (en) * | 1996-01-16 | 1998-09-22 | Rohm Co., Ltd. | Audio signal amplifier circuit and a portable acoustic apparatus using the same |
| CN1206956A (en) * | 1998-08-07 | 1999-02-03 | 李文华 | Amplifier whose final biased current being synchronously controlled by singal change rate |
| JP2002151978A (en) * | 2000-11-10 | 2002-05-24 | Ad Main Inc | Isolated pwm power amplifier |
| CN1462504A (en) * | 2001-03-08 | 2003-12-17 | 恩菲赛克斯有限公司 | High efficiency switching amplifiers |
| CN1604464A (en) * | 2003-10-01 | 2005-04-06 | 日本电气株式会社 | Differential amplifier circuit and drive circuit of liquid crystal display unit using the same |
-
2007
- 2007-06-11 CN CN200710110936XA patent/CN101325404B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4668919A (en) * | 1986-02-19 | 1987-05-26 | Advanced Micro Devices, Inc. | High speed operational amplifier |
| US5812028A (en) * | 1996-01-16 | 1998-09-22 | Rohm Co., Ltd. | Audio signal amplifier circuit and a portable acoustic apparatus using the same |
| CN1206956A (en) * | 1998-08-07 | 1999-02-03 | 李文华 | Amplifier whose final biased current being synchronously controlled by singal change rate |
| JP2002151978A (en) * | 2000-11-10 | 2002-05-24 | Ad Main Inc | Isolated pwm power amplifier |
| CN1462504A (en) * | 2001-03-08 | 2003-12-17 | 恩菲赛克斯有限公司 | High efficiency switching amplifiers |
| CN1604464A (en) * | 2003-10-01 | 2005-04-06 | 日本电气株式会社 | Differential amplifier circuit and drive circuit of liquid crystal display unit using the same |
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| CN101325404A (en) | 2008-12-17 |
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Owner name: DAI ZHIDE Free format text: FORMER OWNER: TAI-1 MICROELECTRONICS CORP. Effective date: 20130716 |
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Effective date of registration: 20130716 Address after: Hsinchu County, Taiwan, China Patentee after: Dai Zhide Address before: Taiwan County, Taipei, China three cities in the North Road, Lane 21, No. 1, building 20 Patentee before: Tai-1 Microelectronics Corp. |
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