CN101753746A - Trapezoidal wave ringing current generating device adopting PWM control - Google Patents
Trapezoidal wave ringing current generating device adopting PWM control Download PDFInfo
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- CN101753746A CN101753746A CN200810218137A CN200810218137A CN101753746A CN 101753746 A CN101753746 A CN 101753746A CN 200810218137 A CN200810218137 A CN 200810218137A CN 200810218137 A CN200810218137 A CN 200810218137A CN 101753746 A CN101753746 A CN 101753746A
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Abstract
The invention relates to a trapezoidal wave ringing current generating device adopting PWM control, which comprises a PWM controller, a low-pass filter, a voltage-current converter, an isolating circuit, a converting circuit and a full-bridge output circuit. The PWM controller is used for generating a PWM signal; the low-pass filter is connected with the PWM controller and converts the PWM signal into a low-voltage trapezoidal wave; the voltage-current converter is connected with the low-pass filter and generates a current signal based on the low-voltage trapezoidal wave; the isolating circuit is connected with the voltage-current converter and transmits the current signal in a low-voltage region to a high-voltage region; the converting circuit is connected with the voltage-current converter and converts the current signal into a voltage signal; and the full-bridge output circuit is connected with the converting circuit and loads the voltage signal to the end of a user line interface circuit. The adoption of rectangular wave in the prior art disenables the ringing of some telephones so as to affect the system compatibility; and the low-voltage trapezoidal control current signal is transmitted to the high-voltage region by the voltage isolating circuit to generate a high-voltage trapezoidal wave ringing current signal in the invention; and consequently, the trapezoidal wave ringing current generating device has the advantages of excellent compatibility, low cost, small volume and high reliability.
Description
Technical field
The present invention relates to telephony, more particularly, relate to a kind of trapezoidal wave ringing current generating device of the PWM of employing control.
Background technology
Development along with communication system, especially networks development, black phone communication system and network communicating system progressively produce fusion, the VOIP gateway cooperates the pattern of black phone both to take traditional use habit of user into account, effectively utilized the low cost of network service again, therefore obtain development fast, in this process, Subscriber Line Interface Circuit has been produced new demand: simple in structure, volume is little, and to adapt to the communication standard of country variant.
The subscriber line interface of subscriber exchange partly needs multiple supply voltage 5v-48v, 25Hz ringing-current source etc. in traditional telephonic communication system, usually user interface circuit all is positioned at telecommunications room, multiplex telephony can be shared a cover power-supply system, average also not high to the single channel cost, but this scheme cost is just too high for the telephone adapter of low capacity system and single channel, and only adopts a kind of power supply usually for convenience of the user in the consumer electronics product in modern times.
The user interface phone also needs to be responsible for sending bell signal to phone, this signal is generally sine wave or the trapezoidal wave that peak-to-peak value is 180v, the traditional PSTN phone adopts independently ringing-current source, obvious this scheme is not suitable for the single channel mini-system, make on the subscribers feeder variation voltage that forms the type square wave and normally reverse at on-hook feed voltage to 48v at more existing mini-systems, this changes voltage can make most of phone produce ring equally, but also having some telephone sets to require ringing-current is sine wave or trapezoidal wave, square wave just can not make this phone ringing like this, has influenced system compatibility.
Summary of the invention
The technical problem to be solved in the present invention is, makes some phone not produce ring and influences the defective of system compatibility at the above-mentioned use square wave of prior art, and a kind of employing PWM (pulse width modulation) is provided the trapezoidal wave ringing current generating device of control.
The technical solution adopted for the present invention to solve the technical problems is: construct a kind of trapezoidal wave ringing current generating device that adopts PWM control, it comprises:
The PWM controller is used to produce pwm signal;
With the low pass filter that described PWM controller is connected, be used for described pwm signal is converted to the low pressure trapezoidal wave;
With the voltage current adapter that described low pass filter is connected, it produces current signal based on described low pressure trapezoidal wave;
With the buffer circuit that described voltage current adapter is connected, be used for the current signal of low-pressure area is transferred to the higher-pressure region;
With the change-over circuit that described voltage current adapter is connected, be used for described current signal is converted to voltage signal;
The full-bridge output circuit that is connected with described change-over circuit is used for described voltage signal is loaded on the Subscriber Line Interface Circuit end.
In trapezoidal wave ringing current generating device of the present invention, described trapezoidal wave ringing current generating device also comprises being connected and is used to increase the emitter follower that drives load capacity between described change-over circuit and the full-bridge output circuit.
In trapezoidal wave ringing current generating device of the present invention, described PWM controller is controlled by software, meets the pwm signal of trapezoidal wave Changing Pattern with output duty cycle.
In trapezoidal wave ringing current generating device of the present invention, described pwm signal is through trapezoidal signal of continuous low pressure of low pass filter output.
In trapezoidal wave ringing current generating device of the present invention, described voltage current adapter comprises the operational amplifier A 1 that is connected with described low pass filter, described buffer circuit comprises the triode Q6 that is connected between described operational amplifier A 1 output and the change-over circuit, and described change-over circuit comprises collector electrode and the feed circuit V that is connected described triode Q6
BatBetween transfer resistance R1.
In trapezoidal wave ringing current generating device of the present invention, described resistance R 1 is converted to pressure drop on the resistance R 1 with described current signal, is sent to described full-bridge output circuit to form voltage signal.
In trapezoidal wave ringing current generating device of the present invention, described emitter follower comprises the triode Q5 that is connected between described change-over circuit and the full-bridge output circuit.
In trapezoidal wave ringing current generating device of the present invention, described triode Q5 is transferred to late-class circuit with the voltage signal that forms, and the minimizing load causes interference to the electric current of described change-over circuit.
In trapezoidal wave ringing current generating device of the present invention, described full-bridge output circuit is penetrated the undistorted end points TIP who is loaded into the subscribers feeder loop of step voltage with described triode Q5's.
In trapezoidal wave ringing current generating device of the present invention, described trapezoidal wave ringing current generating device further comprises the circuit structure that is used for generating at the other end RING of subscribers feeder loop trapezoidal signal.
Implement the trapezoidal wave ringing current generating device of employing PWM of the present invention control, has following beneficial effect: with a voltage isolation circuit the trapezoidal Control current signal of low pressure is transferred to the higher-pressure region to generate the trapezoidal wave ringing current signal of high pressure, has the advantage compatible good, low-cost, that volume is little and reliability is high.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:
Fig. 1 is the circuit theory diagrams of trapezoidal wave ringing current generating device of the present invention;
Fig. 2 is the waveform schematic diagram of pwm signal and low pressure trapezoidal wave;
Fig. 3 is the schematic diagram of trapezoidal wave ringing current generating device partial circuit;
Fig. 4 is the waveform schematic diagram of the trapezoidal wave signal at subscriber line interface two ends.
Embodiment
In order to make technical problem to be solved by this invention, technical scheme and beneficial effect clearer,, the present invention is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
Core concept of the present invention is, with a voltage isolation circuit the trapezoidal Control current signal of low pressure is transferred to the higher-pressure region to generate the trapezoidal wave ringing current signal of high pressure, be sent to the subscriber line interface two ends by the full-bridge output circuit then, trapezoidal wave ringing current generating device of the present invention has the advantage compatible good, low-cost, that volume is little and reliability is high.
As shown in Figure 1, there is shown the circuit theory diagrams of trapezoidal wave ringing current generating device of the present invention.Shown trapezoidal wave ringing current generating device comprises PWM controller 1, low pass filter 2, voltage current adapter 3, buffer circuit 4, change-over circuit 5, emitter follower 6 and full-bridge output circuit 7.Wherein, PWM controller 1 is used to produce pwm signal.Low pass filter 2 is connected with PWM controller 1, is used for pwm signal is converted to the low pressure trapezoidal wave.Voltage current adapter 3 is connected with low pass filter 2, and it produces current signal based on the low pressure trapezoidal wave.Buffer circuit 4 is connected with voltage current adapter 3, is used for the current signal of low-pressure area is transferred to the higher-pressure region.Change-over circuit 5 is connected with voltage current adapter 3, is used for current signal is converted to voltage signal.Full-bridge output circuit 7 is connected with change-over circuit 5, is used for voltage signal is loaded on the Subscriber Line Interface Circuit end, promptly on TIP and the RING line.Emitter follower 6 is connected between change-over circuit 5 and the full-bridge output circuit 7, is used to increase the emitter follower 6 that drives load capacity.PWM controller 1 is controlled by software, is used for the pwm signal that output duty cycle meets the trapezoidal wave Changing Pattern, and this pwm signal is through trapezoidal signal of continuous low pressure of low pass filter 2 outputs.
Voltage current adapter 3 comprises the operational amplifier A 1 that is connected with low pass filter 2, buffer circuit 4 comprises the triode Q6 that is connected between operational amplifier A 1 output and the change-over circuit 5, and change-over circuit 5 comprises collector electrode and the feed circuit V that is connected triode Q6
BatBetween transfer resistance R1.Resistance R 1 is converted to pressure drop on the resistance R 1 with current signal, forms voltage signal with this and is sent to full-bridge output circuit 7.Emitter follower 6 comprises the triode Q5 that is connected between change-over circuit 5 (being transfer resistance R1) and the full-bridge output circuit 7.Triode Q5 is transferred to late-class circuit with the voltage signal that forms, and the minimizing load causes interference to the electric current of change-over circuit 5.Full-bridge output circuit 7 is penetrated the undistorted end points TIP who is loaded into the subscribers feeder loop of step voltage with triode Q5's.
In addition, trapezoidal wave ringing current generating device of the present invention further comprises the circuit structure that is used for generating at the other end RING of subscribers feeder loop trapezoidal signal, other No. one staircase generator is loaded into anti-phase trapezoidal wave on the subscriber line interface RING line, and so just forming a peak value between TIP and RING is 2 times of V
BatTrapezoidal wave.
Now a lot of MCU (microcontroller) are integrated PWM controller, application software generates the pwm signal of various duty ratios easily, meets the pwm signal of trapezoidal wave Changing Pattern in the present invention with software control PWM controller 1 output duty cycle.Pwm signal can generate direct current signal through after the low-pass filtering of low pass filter 2, and its DC component technical method is as follows, supposes that the PWM duty ratio is τ, and amplitude is A, and then the low-frequency signal components of pwm signal is V
DcFor: V
Dc=A * τ.The duty ratio τ of output pwm signal changes with the rule of trapezoidal wave in time in the present invention, just can export a low frequency trapezoidal wave, as shown in Figure 2.The trapezoidal wave of low pass filter 2 outputs has promptly generated a current signal (with reference to partial circuit shown in Figure 3) through a voltage current transducer 3.
Suppose that trapezoidal signal is St, according to the principle of operational amplifier, the reference voltage of amplifier A1 is V
Ref, then the electric current on the resistance R 5 is I
R5=(V
Ref-St)/R3; Same principle can be known I
R3=I
R5Triode Q6 selects that multiplication factor is big, the extremely withstand voltage higher triode of CE for use, because the Q6 base current is very little, can think that the collector current of triode Q6 is identical with emitter current, can obtain: I thus
R1=Ic=Ie=I
R3Q6 can be transferred to the Control current of low-pressure area the higher-pressure region and simultaneously higherly can play the voltage isolation effect because the CE of Q6 is withstand voltage as from the foregoing.
In circuit shown in Figure 1, the A point voltage of transfer resistance R1 is the feed voltage V of system
Bat, the pressure drop on the R1 is I
R1* R1, the B point voltage of R1 is:
Vb＝V
bat-I
r1×R1
＝V
bat-(V
ref-St)×R1/R3
＝V
bat-V
ref×R1/R3+St×R1/R3
Work as V
BatAnd V
RefDuring for definite value, Vb and St are linear relationships, and system's multiplication factor is R1/R3.Further choose V at this
Bat=V
Ref* R1/R3; 0＜St＜V
Ref, so just can obtain Vb is that peak value is V
BatTrapezoidal wave.
If directly add load at the B point,, will make I if load current is excessive
R1=Ic no longer sets up, and the present invention adds one in B point back and penetrates grade follower 6, because the very little electric current that just can not influence on the R1 of the base current of triode Q5 has increased the load-carrying ability of system.
At the subscriber line interface end, the trapezoidal wave that the present invention is ordered B by a full-bridge output circuit 7 is loaded on the TIP line, same principle, other No. one staircase generator is loaded into an anti-phase trapezoidal wave on the RING line, and so just forming a peak value between TIP and RING is 2 times of V
BatTrapezoidal wave, as shown in Figure 4.
The present invention relates to a kind of trapezoidal wave ringing current generating device of the PWM of employing control, it adopts PWM controller 1 output pwm signal, allow this pwm signal through a low pass filter 2, generate the trapezoidal wave of a low pressure, this low pressure trapezoidal wave is amplified to the required high pressure trapezoidal wave signal of subscriber line interface through the amplifying circuit of being made up of operational amplifier and triode, then this signal is handled circuit 7 by a full-bridge of being made up of two triodes and is loaded on the subscribers feeder loop.Core of the present invention is, with a triode (being buffer circuit 4) that plays the voltage buffer action the trapezoidal Control current signal of low pressure is transferred to the higher-pressure region to generate the trapezoidal wave ringing current signal of high pressure.
The above only is preferred embodiment of the present invention, not in order to restriction the present invention, any modification of being done within every the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a trapezoidal wave ringing current generating device that adopts PWM control is characterized in that, comprising:
PWM controller (1) is used to produce pwm signal;
The low pass filter (2) that is connected with described PWM controller (1) is used for described pwm signal is converted to the low pressure trapezoidal wave;
The voltage current adapter (3) that is connected with described low pass filter (2), it produces current signal based on described low pressure trapezoidal wave;
The buffer circuit (4) that is connected with described voltage current adapter (3) is used for the current signal of low-pressure area is transferred to the higher-pressure region;
The change-over circuit (5) that is connected with described voltage current adapter (3) is used for described current signal is converted to voltage signal;
The full-bridge output circuit (7) that is connected with described change-over circuit (5) is used for described voltage signal is loaded on the Subscriber Line Interface Circuit end.
2. trapezoidal wave ringing current generating device according to claim 1, it is characterized in that described trapezoidal wave ringing current generating device also comprises being connected and is used to increase the emitter follower (6) that drives load capacity between described change-over circuit (5) and the full-bridge output circuit (7).
3. trapezoidal wave ringing current generating device according to claim 1 is characterized in that, described PWM controller (1) is controlled by software, meets the pwm signal of trapezoidal wave Changing Pattern with output duty cycle.
4. trapezoidal wave ringing current generating device according to claim 1 is characterized in that, described pwm signal is through trapezoidal signal of continuous low pressure of low pass filter (2) output.
5. trapezoidal wave ringing current generating device according to claim 1, it is characterized in that, described voltage current adapter (3) comprises the operational amplifier A 1 that is connected with described low pass filter (2), described buffer circuit (4) comprises the triode Q6 that is connected between described operational amplifier A 1 output and the change-over circuit (5), and described change-over circuit (5) comprises collector electrode and the feed circuit V that is connected described triode Q6
BatBetween transfer resistance R1.
6. trapezoidal wave ringing current generating device according to claim 5 is characterized in that, described resistance R 1 is converted to pressure drop on the resistance R 1 with described current signal, is sent to described full-bridge output circuit (7) to form voltage signal.
7. trapezoidal wave ringing current generating device according to claim 2 is characterized in that, described emitter follower (6) comprises the triode Q5 that is connected between described change-over circuit (5) and the full-bridge output circuit (7).
8. trapezoidal wave ringing current generating device according to claim 7 is characterized in that, described triode Q5 is transferred to late-class circuit with the voltage signal that forms, and the minimizing load causes interference to the electric current of described change-over circuit (5).
9. trapezoidal wave ringing current generating device according to claim 8 is characterized in that, described full-bridge output circuit (7) is penetrated the undistorted end points TIP who is loaded into the subscribers feeder loop of step voltage with described triode Q5's.
10. according to each described trapezoidal wave ringing current generating device in the claim 1 to 9, it is characterized in that described trapezoidal wave ringing current generating device further comprises the circuit structure that is used for generating at the other end RING of subscribers feeder loop trapezoidal signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008102181379A CN101753746B (en) | 2008-12-09 | 2008-12-09 | Trapezoidal wave ringing current generating device controlled by Pulse Width Modulation (PWM) |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008102181379A CN101753746B (en) | 2008-12-09 | 2008-12-09 | Trapezoidal wave ringing current generating device controlled by Pulse Width Modulation (PWM) |
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| Publication Number | Publication Date |
|---|---|
| CN101753746A true CN101753746A (en) | 2010-06-23 |
| CN101753746B CN101753746B (en) | 2012-05-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2008102181379A Expired - Fee Related CN101753746B (en) | 2008-12-09 | 2008-12-09 | Trapezoidal wave ringing current generating device controlled by Pulse Width Modulation (PWM) |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104518761A (en) * | 2015-01-19 | 2015-04-15 | 河南西瑞医疗电子技术有限公司 | Audio signal edge waveform control circuit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2325931Y (en) * | 1997-02-27 | 1999-06-23 | 深圳市华为通信股份有限公司 | Bell-ringing signal source arrangement |
| CN2765408Y (en) * | 2004-12-03 | 2006-03-15 | 北京新雷能有限责任公司 | Ring current signal generating circuit |
| CN2919680Y (en) * | 2006-04-12 | 2007-07-04 | 瑞谷科技(深圳)有限公司 | Secondary contravariance power tube drive circuit of ringer oscillator |
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2008
- 2008-12-09 CN CN2008102181379A patent/CN101753746B/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104518761A (en) * | 2015-01-19 | 2015-04-15 | 河南西瑞医疗电子技术有限公司 | Audio signal edge waveform control circuit |
| CN104518761B (en) * | 2015-01-19 | 2018-01-30 | 河南西瑞医疗电子技术有限公司 | A kind of audio signal edge waveform control circuit |
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| CN101753746B (en) | 2012-05-09 |
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Granted publication date: 20120509 Termination date: 20191209 |