CA1186025A - Switching amplifier - Google Patents
Switching amplifierInfo
- Publication number
- CA1186025A CA1186025A CA000404165A CA404165A CA1186025A CA 1186025 A CA1186025 A CA 1186025A CA 000404165 A CA000404165 A CA 000404165A CA 404165 A CA404165 A CA 404165A CA 1186025 A CA1186025 A CA 1186025A
- Authority
- CA
- Canada
- Prior art keywords
- amplifier
- switching
- diode
- cascade
- transformer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/217—Class D power amplifiers; Switching amplifiers
- H03F3/2175—Class D power amplifiers; Switching amplifiers using analogue-digital or digital-analogue conversion
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
Abstract of the disclosure The switching amplifier contains several amplifier stages (43),the output signals of which are summed up along a diodecascade (47) in order to generate an output sum signal having a high voltage. The transformers (21, 23) used for direct-current decoupling of the input from the output of the amplifier stages are connected on the primary side to an alternating voltage source (22) and on the secondary side to a rectifier circuit (27, 31, 35). The controlled switching ele-ment (39) is located between this rectifier circuit and the diode cascade.
By means of this arrangement saturation of the transformers by direct-current pulses is prevented and each amplifier stage can be modulated to 100% by using only one transformer.
By means of this arrangement saturation of the transformers by direct-current pulses is prevented and each amplifier stage can be modulated to 100% by using only one transformer.
Description
~ . `
~ he present invention relates to a switching amplifier for analog LF signals, this switching amplifier beingequipped with an A/D conYerter which converts the analog LF signal into at least two pulse sequences, and with at least two amplifier stages of which each one contains a transformer the primary wind-ing of which is connected to a vbltage source and the secondary winding of which is connected to a diode cas-cade~ and at least one switching element for the current to be transmitted from the voltage source to the diode cascade, this switching element being controlled by -the pulse sequence, and with a low-pass filter which is co~nected to the diode cascade.
Switching amplifiers of the type described have a high e~ficiency which is why they are particularly advantageously used for amplifiers wîth a high output power; For example, in German Offenlegungssohrift 29 3~ 445 a s~itching amplifier is-disclosed which is provi~ed as a modulation amplifier for a broadcast transmitter~ For this purpose, this switching amplifier contains a multitude of amplifier stages which are arranged in parallel with each other and each of which is provided with two transformers the primary windings of which can be connected via associated switching elements to a direct voltage source and the secondary windings of which are connected to a diode cascade. The analog LF input signal to be amplified is converted in a known manner into two pulse -trainsthe duration-modulated pulses of which are phase shifted by 180~ The pulses of each pulse train control the switching element for one of the transform-ers in each amplifier stage. Due to -the alternating excitation, effectedin this manner, of the two transform-ers of each amplifier stage the saturation of these transformers can be avoided and the amplifier stages ~L~8~2~ii can be modulated to 100%. Naturally~ with this type of operation the switchiny elements and transformers of each amplifier stage are switched or excited once during each period of the A/D converter and the switch-on or excitation period can be very brief.
In order to reduce the switching losses,another operating method for switching amplifiers has, therefore, also been already suggested. In this known method, the analog LF input signal is also periodically sampled in an A/D converter and a number, corresponding to the instantaneous value of the amplitude of the analog signal~ of equal-duration pulses are generated.
Each pulse is associated with one amplifier stage and each pulse is split into two part pulses which alter-natingly control the switching elements working inconjunction with the two transformers of this amplifier stage. The time duration of each pulse or part pulse has been selected to be such that the txans~ormer is excited over a maximum duration without running into saturation. In this operating mode9 during each A/D
converter period only the number of switching elements and transformers corresponding to the instantaneous value of the analog signal are switched on or excited which makes it possible to achieve a considerable reduction in the switching lossesO
The switching amplifier disclosed requires for the two operating modes described two alternatingly connectible transformers in each amplifier stage. The material expenditure required for this and the switching losses are the greater the higher the output power desired.
It is thus the object of the present invention to create a switching amplifier the amplifier stages of which require only one transformer and only one switch-ing element ~or 100% modulation and the transformer ofwhich can also be excited during several successive periods o~ the A/D converter.
,., z~
_ 3 --- According to the invention, this object is achieved by means of a switching amplifier of the type mentioned initially in which the primary winding of the transformer (in each amplifier stage) is co~nected to an al-ternating voltage source and the amplifier stage contains a rectifier circuit which is connected to the secondary winding of the transformer and the switching ele-ment of whichthere is at leas~ one is connected between one output of this rectifier circuit and the diode cascade.
The new switching amplifier makes it possible to reduce the number of transformers required for a pre-determined output power to one half And the number of the associated switching elements to one quarter and thus to reduce both the material expenditure and the switching losses. In addition, a smaller low-pass filter can be used for the new switching amplifier because it is no longer necessary to generate during each conversion periodtwo pulses which are phase shifted by 180 and to split the pulsesintD two part pulses respectively. Finally9 the new switching amplifier also makes it possible to have an improved quality LF
ou~put signal because the reduced number of switching processes also results in a reduction of the distortion factor and in a reduction of the noise~ -In the text which follows a preferred ~ustrat ive embodiment of the new switching amplifier is des-cribed with the aid of the figures in which Figure 1 shows the simplified block diagram of an embodiment of the new switching amplifier and Figures 2 and 3 show the circuit diagram of a first and a second embodiment of the amplifier stage for the new switching amplifier.
In the embodiment of a s~itching amplifier, shown in Figure 1 in a greatly simplified block dia-- gram, the input terminal 10 for the analog LF input signal to be amplified is connected to the input of an A/D converter 11. The A/D converter is followed by a storage circuit 12 which is associated with a control-lableread-out circuit 13 which has a plurality of out-puts. In addition, a clock generator 14 is provided which supplies the timing clocks for converting the analog input signal into digital signals and for the output of the control signals.
The switching amplifier also contains a trans-former20,theprimary winding 21 of which is connectedto an alternating-voltage source 22. The transformer has several secandary windîngs of which only three second-ary windings 23, 24, 25 are shown for reasons of simpler illustration. Each secondary winding is connected to a rectifier circuit which consists of a half-wave rectifier 27, 28, or 29 of a series-connected choke 31, 32 or 33 and a smoothing capacitor 35, 36 or 37~ The one output of the rectifier circuit is connected toa controllable switching element 39, 40 or 410 Each secondary winding and its associated rectifier circuit and the switching element form an amplifier stage 43, 44 or 45,the ou~puts of which are connected to a diode cascade 47O The diode cascade contains between the co~nections of each amplifier stage one diode 48, 49, ~0. The end of the diode cas-cade is connected via a low-pass filter 52 to the output terminal 53 of the amplifier.
The read-out circuit 13 contains for each of the amplifier stages one separate output which is connected by means of a signal line 55, 56 or 57 to the switching element of the associated amplifier stage.
In order to operate the amplifier described, the primary winding 21 of thetransformer 20 is connec-ted to the alternating-voltage source 22. Then in each secondary winding 23, ~4, 25 an alternating voltage is induced which is rectified by the associated recti~ier 27,28 or 29 and charges the capacitor 359 36 or 37 to the appropriate direct voltage.
Let it be assumed, for the purpose o~ the des-5 --cription ~ollowing, that all switching elements 39, 40, 41 are switched off and that, therefore, no current is flowing from the amplifier stages 43, 44, or 45 to the diode cascade 47.
The analog signal conducted from the input term-inal to the A/D converter 11 is sampled in predetermined time intervals and during this process a digital signal is generated which corresponds to the instantaneous value of the amplitude and which is stored in the storage circui~t 12~ In a preferred opera~ting mode, the maximum convertible voltage value of the amplitude is subdivided into voltage ranges the number of which is equal to the number of amplifier stages. The digital output signal of the converter is then a number which is equal to the number of voltage ranges which corresponds to the instantaneous value of the amplitude of the analog signal. This digital signal sets in the storage circuit 12 a number of storage locations which is equal to its number. The read-out circuit 13 periodically reads out the storage content and generates for each storage location set one switch-on signal which is applied to one o~ the signal lines 55, 56~ 57 and fed to the corresponding switching element 39, 40 or 41.
In this way a number of switching elements corresponding to the instantaneous value of the amplitude of the analog signal is switched on and the direct u~lt-ages applied to the associated capacitors are series-connected along the diode cascade. In this process, for the period of time between two switching cycles a voltage is generated across the diode cascade~ this volt-age being proportional to the sum of the voltage ranges 9 determined in the A/D conver-ter, of the analog input signal. The voltage steps generated across the diode cascade during the switching-on and switching-off of switching elemen-ts are smoothed out by the low-pass filter 52 so that at the output terminal 53 an analog signal appears which corresponds to the amplified input signal.
In order to achieve uniform distribution of the loading of the individual amplifier stages, it is of advantage to select the same output voltage for most of the amplifier stages.
In addition to that, at least one amplifier stage can be sub-divided into further sub-stages the output voltages of which are provided with binary weighting and which are controlled by a corresponding binary-coded signal of the read-out circuit 13. In this way, the voltage steps occurring at the diode cascadeandthus the amplifier-related wavyness of the output signal can be reduced.
Naturally, the transformer can for simplicity's sake be connected to an industrial alternating voltage source providing, for example~ 220 V/50 Hz. However7 it is also possible to use a 3-phase transformer for 380 V/50 Hz. Inthe latter case, the primary and secondary windings shown in -E~gure 1 consist of three ~inding parts and the rectifîer arrangement is correspondingly const-ructed as a three-phase rectifier~
It is also understood that~-instead of -the one transformer sho~n, having one primary and a plurality of secondary windi-ngs, also a plurality of transformers having each one primary and one secondary winding can be used.
In order to obtain better agreement the charact-eristic of the analog input signal with the envelope curve of the direct voltages added across the diodecascade, the A/D converter 11 can be followed in the circuit by an arithmetic unit which determines the difference between the instantaneous value of the amplitude of the analog input signal and the closest digital value formed from the voltage ranges and generates ~ia the read-out circuit 13 an additional time-delayed con-trol signal, the time delay being inversely propor-tional to the difference thus determined. It is of particular advantage if during successive read-out cycles only such switch-on or switch-off signals are generated as correspond to the change in the analog input signal which has in the meantime taken place. This makes it possible to achieve a considerable reduction in the total number of switching processes and the associated switching losses. Such operating modes are already known as initially mentioned, which is why they are not being discussed in detail.
In order to make it possible to add up along the diode cascade the voltages generated by the ampli-fier stages 9 only one amplifier stage must be connected to the ground line. Each of the other "floating" ampli-fier stages is at a higher voltage the value of which is changeable and depends on the number of amplifier stages switched on and on the ordinal number of the individual amplifier stage along the diode cascacle.
In contrast to that, the switching signals generated by the read-out eireuit have a eonstant voltage with respeet to the ground line whieh is why the switching signals eannot be fed direetly to the switehing ele-mentsO Figure 2 shows an amplifier stage 60 and an arrangement, eonstrueted as opto-coupler 61, for the direct-eurrent deeoupling of the signal line from the switehing element. The ampllfier stage contains, in agreement with the embodiment according to Figure 1, a seeondary winding 63, a reetifier 64, a choke 65, a smoothing eapacitor 66 and a switeh 67~ The switeh is a field effeet transistor the gate of which is eonneeted to the photodiode 70 of the opto-couplerO
The light-emitting diode 71 of the opto-coupler is eonneeted to a signal line 72. So that reliable insulation between the light-emitting diode and photo~
diode is ensured even at high potential differences9 a fiber-optic wave guide 73 can be used for transmitt-ing the lightO
7a -Instead o~ the field effect transistor shown, other semiconductor components such as a bipolar trans~
istor can also be used. In addition, an amplifier can be connected between the photodiode and the switch if the output signal of the photodiode is not capable of driving the switch directly. ~
The single-phase rectifier circuit shown in Figures 1 and 2 has been constructed as a half-wave rectifier for the sake of simplicity. Naturally, a center-tap or full-wave circuit or a full-wave diode bridge can also be used in order to reduce the ripple of the direct voltage.
If~ as has been mentioned above, athree~phase transformer is used and -the amplifier stage contains a three-partsecondary winding,then astar or double-star rectifier circuit can also be used instead of the three-phase bridge rectifier which has also been mentioned.
Figure 3 shows another embodiment of an ampli-fier stage 80t the rectifier devi~e of which is const-ructed as a full-wave rectifier for voltage doubling purposes. For this purpose9 the one end of the secondary winding 81 is connected via two anti-parailel connecteddiodes 82, 83 and associated chokes 84 and 85, respectively~ to one terminal of two capacitors 87 and 88, respectively9 and the other end of the secondary winding is connected directly to the connecting point 89 of the other terminals of the capacitors. The one terminal of each capacitor is also connected via a switching element 91 and 92 J respectively, and the connec-ting point 89 of the two other capacitor terminals is connected direc-tly to the diodecascade 9~ which has bet-ween each of the individual connections one diode 94, 95.
The single-phase rectifier device shown, with full-rectification can also be constructed as a center-tapped circuit like the abovementioned device with half-~ve rectification, and fora three-phase transformer as a star or double-star recti~ier circuit.
~ he present invention relates to a switching amplifier for analog LF signals, this switching amplifier beingequipped with an A/D conYerter which converts the analog LF signal into at least two pulse sequences, and with at least two amplifier stages of which each one contains a transformer the primary wind-ing of which is connected to a vbltage source and the secondary winding of which is connected to a diode cas-cade~ and at least one switching element for the current to be transmitted from the voltage source to the diode cascade, this switching element being controlled by -the pulse sequence, and with a low-pass filter which is co~nected to the diode cascade.
Switching amplifiers of the type described have a high e~ficiency which is why they are particularly advantageously used for amplifiers wîth a high output power; For example, in German Offenlegungssohrift 29 3~ 445 a s~itching amplifier is-disclosed which is provi~ed as a modulation amplifier for a broadcast transmitter~ For this purpose, this switching amplifier contains a multitude of amplifier stages which are arranged in parallel with each other and each of which is provided with two transformers the primary windings of which can be connected via associated switching elements to a direct voltage source and the secondary windings of which are connected to a diode cascade. The analog LF input signal to be amplified is converted in a known manner into two pulse -trainsthe duration-modulated pulses of which are phase shifted by 180~ The pulses of each pulse train control the switching element for one of the transform-ers in each amplifier stage. Due to -the alternating excitation, effectedin this manner, of the two transform-ers of each amplifier stage the saturation of these transformers can be avoided and the amplifier stages ~L~8~2~ii can be modulated to 100%. Naturally~ with this type of operation the switchiny elements and transformers of each amplifier stage are switched or excited once during each period of the A/D converter and the switch-on or excitation period can be very brief.
In order to reduce the switching losses,another operating method for switching amplifiers has, therefore, also been already suggested. In this known method, the analog LF input signal is also periodically sampled in an A/D converter and a number, corresponding to the instantaneous value of the amplitude of the analog signal~ of equal-duration pulses are generated.
Each pulse is associated with one amplifier stage and each pulse is split into two part pulses which alter-natingly control the switching elements working inconjunction with the two transformers of this amplifier stage. The time duration of each pulse or part pulse has been selected to be such that the txans~ormer is excited over a maximum duration without running into saturation. In this operating mode9 during each A/D
converter period only the number of switching elements and transformers corresponding to the instantaneous value of the analog signal are switched on or excited which makes it possible to achieve a considerable reduction in the switching lossesO
The switching amplifier disclosed requires for the two operating modes described two alternatingly connectible transformers in each amplifier stage. The material expenditure required for this and the switching losses are the greater the higher the output power desired.
It is thus the object of the present invention to create a switching amplifier the amplifier stages of which require only one transformer and only one switch-ing element ~or 100% modulation and the transformer ofwhich can also be excited during several successive periods o~ the A/D converter.
,., z~
_ 3 --- According to the invention, this object is achieved by means of a switching amplifier of the type mentioned initially in which the primary winding of the transformer (in each amplifier stage) is co~nected to an al-ternating voltage source and the amplifier stage contains a rectifier circuit which is connected to the secondary winding of the transformer and the switching ele-ment of whichthere is at leas~ one is connected between one output of this rectifier circuit and the diode cascade.
The new switching amplifier makes it possible to reduce the number of transformers required for a pre-determined output power to one half And the number of the associated switching elements to one quarter and thus to reduce both the material expenditure and the switching losses. In addition, a smaller low-pass filter can be used for the new switching amplifier because it is no longer necessary to generate during each conversion periodtwo pulses which are phase shifted by 180 and to split the pulsesintD two part pulses respectively. Finally9 the new switching amplifier also makes it possible to have an improved quality LF
ou~put signal because the reduced number of switching processes also results in a reduction of the distortion factor and in a reduction of the noise~ -In the text which follows a preferred ~ustrat ive embodiment of the new switching amplifier is des-cribed with the aid of the figures in which Figure 1 shows the simplified block diagram of an embodiment of the new switching amplifier and Figures 2 and 3 show the circuit diagram of a first and a second embodiment of the amplifier stage for the new switching amplifier.
In the embodiment of a s~itching amplifier, shown in Figure 1 in a greatly simplified block dia-- gram, the input terminal 10 for the analog LF input signal to be amplified is connected to the input of an A/D converter 11. The A/D converter is followed by a storage circuit 12 which is associated with a control-lableread-out circuit 13 which has a plurality of out-puts. In addition, a clock generator 14 is provided which supplies the timing clocks for converting the analog input signal into digital signals and for the output of the control signals.
The switching amplifier also contains a trans-former20,theprimary winding 21 of which is connectedto an alternating-voltage source 22. The transformer has several secandary windîngs of which only three second-ary windings 23, 24, 25 are shown for reasons of simpler illustration. Each secondary winding is connected to a rectifier circuit which consists of a half-wave rectifier 27, 28, or 29 of a series-connected choke 31, 32 or 33 and a smoothing capacitor 35, 36 or 37~ The one output of the rectifier circuit is connected toa controllable switching element 39, 40 or 410 Each secondary winding and its associated rectifier circuit and the switching element form an amplifier stage 43, 44 or 45,the ou~puts of which are connected to a diode cascade 47O The diode cascade contains between the co~nections of each amplifier stage one diode 48, 49, ~0. The end of the diode cas-cade is connected via a low-pass filter 52 to the output terminal 53 of the amplifier.
The read-out circuit 13 contains for each of the amplifier stages one separate output which is connected by means of a signal line 55, 56 or 57 to the switching element of the associated amplifier stage.
In order to operate the amplifier described, the primary winding 21 of thetransformer 20 is connec-ted to the alternating-voltage source 22. Then in each secondary winding 23, ~4, 25 an alternating voltage is induced which is rectified by the associated recti~ier 27,28 or 29 and charges the capacitor 359 36 or 37 to the appropriate direct voltage.
Let it be assumed, for the purpose o~ the des-5 --cription ~ollowing, that all switching elements 39, 40, 41 are switched off and that, therefore, no current is flowing from the amplifier stages 43, 44, or 45 to the diode cascade 47.
The analog signal conducted from the input term-inal to the A/D converter 11 is sampled in predetermined time intervals and during this process a digital signal is generated which corresponds to the instantaneous value of the amplitude and which is stored in the storage circui~t 12~ In a preferred opera~ting mode, the maximum convertible voltage value of the amplitude is subdivided into voltage ranges the number of which is equal to the number of amplifier stages. The digital output signal of the converter is then a number which is equal to the number of voltage ranges which corresponds to the instantaneous value of the amplitude of the analog signal. This digital signal sets in the storage circuit 12 a number of storage locations which is equal to its number. The read-out circuit 13 periodically reads out the storage content and generates for each storage location set one switch-on signal which is applied to one o~ the signal lines 55, 56~ 57 and fed to the corresponding switching element 39, 40 or 41.
In this way a number of switching elements corresponding to the instantaneous value of the amplitude of the analog signal is switched on and the direct u~lt-ages applied to the associated capacitors are series-connected along the diode cascade. In this process, for the period of time between two switching cycles a voltage is generated across the diode cascade~ this volt-age being proportional to the sum of the voltage ranges 9 determined in the A/D conver-ter, of the analog input signal. The voltage steps generated across the diode cascade during the switching-on and switching-off of switching elemen-ts are smoothed out by the low-pass filter 52 so that at the output terminal 53 an analog signal appears which corresponds to the amplified input signal.
In order to achieve uniform distribution of the loading of the individual amplifier stages, it is of advantage to select the same output voltage for most of the amplifier stages.
In addition to that, at least one amplifier stage can be sub-divided into further sub-stages the output voltages of which are provided with binary weighting and which are controlled by a corresponding binary-coded signal of the read-out circuit 13. In this way, the voltage steps occurring at the diode cascadeandthus the amplifier-related wavyness of the output signal can be reduced.
Naturally, the transformer can for simplicity's sake be connected to an industrial alternating voltage source providing, for example~ 220 V/50 Hz. However7 it is also possible to use a 3-phase transformer for 380 V/50 Hz. Inthe latter case, the primary and secondary windings shown in -E~gure 1 consist of three ~inding parts and the rectifîer arrangement is correspondingly const-ructed as a three-phase rectifier~
It is also understood that~-instead of -the one transformer sho~n, having one primary and a plurality of secondary windi-ngs, also a plurality of transformers having each one primary and one secondary winding can be used.
In order to obtain better agreement the charact-eristic of the analog input signal with the envelope curve of the direct voltages added across the diodecascade, the A/D converter 11 can be followed in the circuit by an arithmetic unit which determines the difference between the instantaneous value of the amplitude of the analog input signal and the closest digital value formed from the voltage ranges and generates ~ia the read-out circuit 13 an additional time-delayed con-trol signal, the time delay being inversely propor-tional to the difference thus determined. It is of particular advantage if during successive read-out cycles only such switch-on or switch-off signals are generated as correspond to the change in the analog input signal which has in the meantime taken place. This makes it possible to achieve a considerable reduction in the total number of switching processes and the associated switching losses. Such operating modes are already known as initially mentioned, which is why they are not being discussed in detail.
In order to make it possible to add up along the diode cascade the voltages generated by the ampli-fier stages 9 only one amplifier stage must be connected to the ground line. Each of the other "floating" ampli-fier stages is at a higher voltage the value of which is changeable and depends on the number of amplifier stages switched on and on the ordinal number of the individual amplifier stage along the diode cascacle.
In contrast to that, the switching signals generated by the read-out eireuit have a eonstant voltage with respeet to the ground line whieh is why the switching signals eannot be fed direetly to the switehing ele-mentsO Figure 2 shows an amplifier stage 60 and an arrangement, eonstrueted as opto-coupler 61, for the direct-eurrent deeoupling of the signal line from the switehing element. The ampllfier stage contains, in agreement with the embodiment according to Figure 1, a seeondary winding 63, a reetifier 64, a choke 65, a smoothing eapacitor 66 and a switeh 67~ The switeh is a field effeet transistor the gate of which is eonneeted to the photodiode 70 of the opto-couplerO
The light-emitting diode 71 of the opto-coupler is eonneeted to a signal line 72. So that reliable insulation between the light-emitting diode and photo~
diode is ensured even at high potential differences9 a fiber-optic wave guide 73 can be used for transmitt-ing the lightO
7a -Instead o~ the field effect transistor shown, other semiconductor components such as a bipolar trans~
istor can also be used. In addition, an amplifier can be connected between the photodiode and the switch if the output signal of the photodiode is not capable of driving the switch directly. ~
The single-phase rectifier circuit shown in Figures 1 and 2 has been constructed as a half-wave rectifier for the sake of simplicity. Naturally, a center-tap or full-wave circuit or a full-wave diode bridge can also be used in order to reduce the ripple of the direct voltage.
If~ as has been mentioned above, athree~phase transformer is used and -the amplifier stage contains a three-partsecondary winding,then astar or double-star rectifier circuit can also be used instead of the three-phase bridge rectifier which has also been mentioned.
Figure 3 shows another embodiment of an ampli-fier stage 80t the rectifier devi~e of which is const-ructed as a full-wave rectifier for voltage doubling purposes. For this purpose9 the one end of the secondary winding 81 is connected via two anti-parailel connecteddiodes 82, 83 and associated chokes 84 and 85, respectively~ to one terminal of two capacitors 87 and 88, respectively9 and the other end of the secondary winding is connected directly to the connecting point 89 of the other terminals of the capacitors. The one terminal of each capacitor is also connected via a switching element 91 and 92 J respectively, and the connec-ting point 89 of the two other capacitor terminals is connected direc-tly to the diodecascade 9~ which has bet-ween each of the individual connections one diode 94, 95.
The single-phase rectifier device shown, with full-rectification can also be constructed as a center-tapped circuit like the abovementioned device with half-~ve rectification, and fora three-phase transformer as a star or double-star recti~ier circuit.
Claims (9)
1. A switching amplifier for analog LF signals, this switching amplifier being equipped with an A/D
converter which converts the analog LF signal into at least two pulse sequences, and with at least two amplifier stages of which each one contains a transformer the primary winding of which is connected to a voltage source and the secondary winding of which is connected to a diode cascade, and at least one switching ele-ment for the current to be transmitted from the voltage source to the diodecascade, this switching element being.
controlled by the pulse sequence, and with a low-pass filter which is connected to the diode cascade, wherein the primary winding (21) of the transformer (20) is connected to an alternating-voltage source (22) and the amplifier stage (43, 44,45) contains a rectifier circuit (27, 31, 35; 28, 32, 36; 29, 33, 37) which is connected to the secondary winding (23, 24, 25) of the transformer and the switching element (39, 40, 41) of which there is at least one is connected between one output of this rec-tifier circuit and the diode cascade (47).
converter which converts the analog LF signal into at least two pulse sequences, and with at least two amplifier stages of which each one contains a transformer the primary winding of which is connected to a voltage source and the secondary winding of which is connected to a diode cascade, and at least one switching ele-ment for the current to be transmitted from the voltage source to the diodecascade, this switching element being.
controlled by the pulse sequence, and with a low-pass filter which is connected to the diode cascade, wherein the primary winding (21) of the transformer (20) is connected to an alternating-voltage source (22) and the amplifier stage (43, 44,45) contains a rectifier circuit (27, 31, 35; 28, 32, 36; 29, 33, 37) which is connected to the secondary winding (23, 24, 25) of the transformer and the switching element (39, 40, 41) of which there is at least one is connected between one output of this rec-tifier circuit and the diode cascade (47).
2. A switching amplifier as claimed in claim 1, wherein the rectifier circuit (27, 31, 35; 28, 32, 36;
29, 33, 37) is provided with two outputs of which one is collected to thediode cascade (47) via the switching element (39, 40, 41) and the other is connected directly to the diodecascade (47) and between the two connecting points at least one diode (50, 49, 48) is provided.
29, 33, 37) is provided with two outputs of which one is collected to thediode cascade (47) via the switching element (39, 40, 41) and the other is connected directly to the diodecascade (47) and between the two connecting points at least one diode (50, 49, 48) is provided.
3. A switching amplifier as claimed in claim 1, where-in the rectifier circuit is provided with three outputs of which two are connected to thediode cascade (93) via a switching element (91, 92) and the third one is direc-tly connected to the diode cascade (93) which is provided between the first and the third and between the third and the other connecting point with at least one diode (94, 95).
4. A switching amplifier as claimed in claim 1, wherein the transformers of the amplifier stages (43, 44, 45) are combined into one transformer (20) having one primary winding (21) and a number of secondary wind-ings (23, 24, 25) which corresponds to the number of amplifier stages (43, 44, 45).
5. A switching amplifier as claimed in claim 1, wherein the output voltages of most of the amplifier stages are identical.
6. A switching amplifier as claimed in claim 1, wherein at least one amplifier stage is subdivided into sub-stages and the output voltages of the subs-tages are provided with binary weighting.
A switching amplifier as claimed in claim 1, wherein for the purpose of direct-current decoupling of the control electrode of the switching element (67) from the control pulse line (72) a device (71) for converting the electric control pulses into optical signals and a further device (70) for reconverting the optical signals into electric control pulses is provided.
8. A switching amplifier as claimed in claim 4, wherein between the one and the other device (71 and 70 respectively) a fiber-optic wave guide (73) is disposed,
9. A switching amplifier as claimed in claim 1, wherein for the purpose of direct-current decoupling of the control electrode of the switching elements from the control pulse line a device for converting the electric control pulses into optical signals and switching ele-ments which can be controlled with optical signals are provided.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH357881 | 1981-06-01 | ||
| CH3578/81-7 | 1981-06-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1186025A true CA1186025A (en) | 1985-04-23 |
Family
ID=4259012
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000404165A Expired CA1186025A (en) | 1981-06-01 | 1982-05-31 | Switching amplifier |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0066904B1 (en) |
| JP (1) | JPS57203304A (en) |
| CA (1) | CA1186025A (en) |
| DE (1) | DE3265563D1 (en) |
| IN (1) | IN156015B (en) |
| YU (1) | YU44424B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5345198A (en) * | 1993-06-10 | 1994-09-06 | Crown International, Inc. | Power supply modulator circuit for transmitter |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0124765B1 (en) * | 1983-05-10 | 1987-09-02 | BBC Brown Boveri AG | Digital power switching amplifier |
| DE3502135A1 (en) * | 1985-01-19 | 1986-07-24 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Circuit arrangement of a switching amplifier |
| DE3534979A1 (en) * | 1985-07-25 | 1987-01-29 | Licentia Gmbh | POWER SUPPLY |
| EP0218152B1 (en) * | 1985-09-28 | 1990-12-05 | Licentia Patent-Verwaltungs-GmbH | Switching amplifier |
| DE3822990A1 (en) * | 1988-07-07 | 1990-01-11 | Olympia Aeg | POWER AMPLIFIER |
| DE3907919A1 (en) * | 1988-07-07 | 1990-01-11 | Olympia Aeg | POWER AMPLIFIER |
| EP2437386A1 (en) | 2010-10-04 | 2012-04-04 | PL Technologies AG | Stabilized high-voltage power supply |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3480881A (en) * | 1966-08-19 | 1969-11-25 | Westinghouse Electric Corp | Circuitry for simultaneously modulating and amplifying a carrier signal |
| JPS5916443B2 (en) * | 1976-02-06 | 1984-04-16 | ソニー株式会社 | power amplifier |
| US4153882A (en) * | 1978-03-24 | 1979-05-08 | Fisher Charles B | High-efficiency amplifier |
| DE2935445A1 (en) * | 1979-08-09 | 1981-02-26 | Bbc Brown Boveri & Cie | NF POWER AMPLIFIER |
| DE2939365C2 (en) * | 1979-09-28 | 1984-11-15 | Deutsche Itt Industries Gmbh, 7800 Freiburg | Class D power amplifiers |
| GB2064901B (en) * | 1979-11-30 | 1984-11-07 | Harris Corp | Digital high power amplifier |
-
1982
- 1982-04-29 EP EP19820200509 patent/EP0066904B1/en not_active Expired
- 1982-04-29 DE DE8282200509T patent/DE3265563D1/en not_active Expired
- 1982-05-13 IN IN534/CAL/82A patent/IN156015B/en unknown
- 1982-05-24 YU YU109382A patent/YU44424B/en unknown
- 1982-05-28 JP JP57090010A patent/JPS57203304A/en active Granted
- 1982-05-31 CA CA000404165A patent/CA1186025A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5345198A (en) * | 1993-06-10 | 1994-09-06 | Crown International, Inc. | Power supply modulator circuit for transmitter |
| US5736906A (en) * | 1993-06-10 | 1998-04-07 | Crown International, Inc. | Power supply modulator circuit for transmitter |
| US5949296A (en) * | 1993-06-10 | 1999-09-07 | Crown International, Inc. | Power supply modulator circuit for transmitter |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3265563D1 (en) | 1985-09-26 |
| YU44424B (en) | 1990-08-31 |
| EP0066904A1 (en) | 1982-12-15 |
| IN156015B (en) | 1985-04-27 |
| YU109382A (en) | 1985-12-31 |
| JPH0582767B2 (en) | 1993-11-22 |
| EP0066904B1 (en) | 1985-08-21 |
| JPS57203304A (en) | 1982-12-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1189138A (en) | Bi-lateral four quadrant power converter | |
| EP0083727B1 (en) | Amplitude modulator | |
| US4479175A (en) | Phase modulated switchmode power amplifier and waveform generator | |
| US4847742A (en) | Multi-channel inverter circuit | |
| WO1988005224A1 (en) | Regulated ac/dc converter | |
| CA1114536A (en) | Ringing generator | |
| CA1186025A (en) | Switching amplifier | |
| US4882664A (en) | Synchronous modulation circuit | |
| WO1985002504A1 (en) | Ripple reduction circuit for an inverter | |
| JP2004289993A (en) | Control method of switch mode power supply | |
| US4132930A (en) | Brushless D-C motor with several Y connected phase windings | |
| US4245288A (en) | Elimination of current spikes in buck power converters | |
| US4246528A (en) | System for controlling alternating current motors | |
| US5163174A (en) | Power amplifier | |
| US3976931A (en) | AC regulator | |
| US3188394A (en) | Low-level time division multiplex system | |
| JPH066969A (en) | Constant voltage power supply | |
| CA1298612C (en) | Voltage regulation for three-phase inverter | |
| US3340456A (en) | Voltage controlled power converter circuits | |
| JPS60197162A (en) | Switching power source | |
| SU961078A1 (en) | Solid-state inverter | |
| CA1179015A (en) | Twin transformer inverter | |
| SU775846A1 (en) | Two-cycle adjustable inverter | |
| US5006776A (en) | Gate-controlled electric drive | |
| JPS6315511A (en) | Isolator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |