CA1186755A - Voltage controlled oscillator - Google Patents
Voltage controlled oscillatorInfo
- Publication number
- CA1186755A CA1186755A CA000386729A CA386729A CA1186755A CA 1186755 A CA1186755 A CA 1186755A CA 000386729 A CA000386729 A CA 000386729A CA 386729 A CA386729 A CA 386729A CA 1186755 A CA1186755 A CA 1186755A
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- output
- signal
- producing
- node
- 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
Landscapes
- Amplifiers (AREA)
- Dc-Dc Converters (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A voltage controlled oscillator having an operational amplifier connected to receive a known voltage from a reference voltage source and the output of a switching regulator circuit. The operational amplifier provides an output signal which is utilized after amplification by a transistor as an input to the resistive input of a current mirror of a pulse width modula-tor. The pulse width modulator is capable of providing a digital pulse stream as an output having a frequency in the range of 0 to 400 KHz in response to the output of the operational amplifier.
A voltage controlled oscillator having an operational amplifier connected to receive a known voltage from a reference voltage source and the output of a switching regulator circuit. The operational amplifier provides an output signal which is utilized after amplification by a transistor as an input to the resistive input of a current mirror of a pulse width modula-tor. The pulse width modulator is capable of providing a digital pulse stream as an output having a frequency in the range of 0 to 400 KHz in response to the output of the operational amplifier.
Description
5202~53 5PECIFICATION ~OR
Y~LTAGE CONTROLLED OSCILLATOR
-B~CXGROUND OF ~HE I`NVENTION
lo ~ield of the Invention. This invention relates to a voltage controlled oscillator which provides a digital pulse stream, and~ more particularly, this invention relates to a voltage controlled oscillator produciny a digi~al pulse stream having a stable frequency in the range of 0 to 400 KHz .
Y~LTAGE CONTROLLED OSCILLATOR
-B~CXGROUND OF ~HE I`NVENTION
lo ~ield of the Invention. This invention relates to a voltage controlled oscillator which provides a digital pulse stream, and~ more particularly, this invention relates to a voltage controlled oscillator produciny a digi~al pulse stream having a stable frequency in the range of 0 to 400 KHz .
2 Description of tile Prior Art. Various types of voltage controlled oscillators are known in prior art. In many applications it is desirable to control, for example, the output of a r~gulated power supply by ~tilizing a voltage controlled oscillator to generate a pulse stream which has a freq~ency determined by the deviation of the ou~put voltage of the regulated power supply from a predetermined reference voltage. In particu-lar, it is desirable that voltage controlled oscillators which produce a digital pulse stream to be utilized with switching r~gulator circuits are both capable of a wide frequency range and stable. A control circuit for a switching regulator circuit is shown in U. S. Patent No. 4,045,887 issued to Nowell on 5eptember 6, 1977, and entitled 'Switching Regulator Control Circui~"~ As shown in the Nowell patent, a clock generator is utilized to praduce the necessary digital pulse stream which is dis~ributed to the various se~iconductor controlled rectiiers (hereinafter referred to as SCRs) o~ ~he ~witchi~ regulator circuit. AS the camplexity o switching r~gulator circuits ~s increased, it has been found desirable for the switchin~ regulator circuit to have the capability of providing a stable oukput voltage over loads varying from 1 to 100 percent. Therefore, i~ is highly desirable to have a voltage controlled oscillator which is capable of producing a digital pulse stream which is stable in frequency over a wide range. Specifically, it is desirable that the voltage controlled oscillator produce a digital pulse stream having a frequency in the range of 0 to 400 KHz.
The type of switching regulator circuit requiring such a wide range of fre-quencies of the digital pulse stream ram a voltage controlled oscillator is shown in ~. S. Patent No. 4,142,231 issued to Wilson et al. on February 27, 1979, and entitled "High Current Low Voltage Liquid Cooled Switching Regulator DC Power Supply". The improvement of the voltage controlled oscillator producing the digital pulse stream was required by an increase in the maximum frequency and therefore the firing rate per SCR. The increased firing rate per SCR requires improved control of the interval between the gating pulses to the SCRs to ensure that the SCRs recover fully prior to application of the next ga~e impulse to actua~e the SCR. If an ~CR is actuated prior to full recovery fron its prior actuation, the SCR
can fail catastrophically.
None of ~he prior constructions shows a voltage controlled oscillator which is caFable of producing a digital pulse stream having a frequency stable in ~he ran~e of 0 to 400 KHz.
~67~i;S
SUMM~RY OF THE INVENTION
A new and improved voltage controlled oscillator for utilization with a control circuit for a switching regulator circuit is shown herein. The output voltage is received by the voltage controlled oscillator. The predetermined voltage and ~he output voltage are inputs to an operational amplifier. The predetenmined voltage level is provided rom a reference source of stable DC voltage. The output of the operational amplifier varies in proportion to the deviation of the output voltage from the predetermined voltage level. Thus, the deviation of the output voltage from a predetermined voltage level is utilized by the operational amplifier ~o form a signal. This signal has its magnitude varied in propor~ion to the deviation of the output voltage from the predetermined voltage level.
The signal produced by the operational amplifier is amplified by a transis-tor ]ocated intermediate the operational amplifier and a pulse width mod~-la~or. The signal becomes an input to the resistive input of the current mirror of the pulse width modulator. m e source of reference voltage and the output voltage of the switching regulator circuits are provided to a comparator. The output of the comparator forms an actuation signal which is applied to ac~uate both the transistor a~d the operational amplifier. A
second operational amplifier is connected to the output voltage of the swi~ching regula~or circuit and to the reference voltage source. The second operational amplifier has a feedback loop comprisiny a capacitor and resistor with its output connected to the collector of ~he ~ransistor.
'~his second operational amplirier provides an initial current to the cur-rent mirror of the p~Lse width modulator durin~ startup~ m e collector is t,7C~
5202~53 ~he portion of the transistor connected to the resistive input of the cur-rent mirror of the pulse width modulator. The output signal produced by the- operational amplifier is amplified by the transistor to provide a well-defined current as an input to the resistive input of khe current mir-ror of pulse width modulator. The greater the signal generated by the operational amplifier, the greater the current flow to the current mirror of the pulse width modulator as amplified by the transistor. As the devia-tion between the predetermined voltage and the output voltage decreases, ~he magnitude of the signal produced by the operational amplifier decreases. The higher the current the greater the freq~ency of the diyital pulse stream produced by the pulse width modulator, the lesser the magni-tude of the signal produced by the operational amplifier as the signal from the operational amplifier decreases and therefore the decreased current from the collector of the transistor to the current mirror. As the current to the resistive input of the current mirror decreases, the frequency of digital pulse stream produced by the pulse width modulator decreases.
For example, if the load connected to the output of the switching regulator circuit increases, the output voltage tends to decrease. This decrease causes a deviation between the predetermined output voltage and the actual output voltage. The output signal of the operational amplifier increases a~d therefore the output of the transistor to the resistive input of the current mirror of the pulse width modulator increases which in turn increases the frequency of the digital pulse stream produced ~y the voltage controlled oscillator. The increased frequency of the digi~al pulse stream results in the SCRs being fired at a higher rate and, therefore, more ener-gy is transferred to the output of the switching regula-tor circuit to main-tain the output voltage at approxima.tely the predeterm:ined output voltage.
It is an advantage oi the present invention to provide a voltage controlled osci.llator capable of producing a. digita.l pulse stream having a stable frequency in the range of approximately 0 to ~00 Kllz.
It is a further advantage of the present invention to provide a voltage controlled oscillator utilizing a pulse width modulator capable of generati.ng a. stable digital pulse stream having a frequency in the ra.nge of 0 to ~00 KHz.
Allother advantage of the present invention is to provide a voltage controlled oscilkltor which responds to the devia.tion of an output voltage :Erom a predetermined voltage level by varying the frequency of the digital pulse strea.m produced within the range of 0 to ~00 KHz In a.ccordance with the present invention, there is provided a voltage controlled oscillator producing a di.gital pulse stream ilaving a frequency within the range of 0 to ~00 KHz, comprising:
a. Comparator connected to receive a reference voltage and the output voltage of a. switching regulator circuit for producing a first signal when said reference voltage is present;
b. An operational amplifier opera.tively connected to receive said first signa.l, said reference voltage, a.nd the output voltage of said switching regulator circuit producing a.t an output thereof a second signal havi.ng a. magnitude directly related to the deviation of sa:id output volta.ge from a determined volta.ge level; and _5_ 7'`~`~
c. A pulse width modulator operatively connec~:ed to receive said second signal at a resistor input of a current mirror therein for varying the frequency o-f said digital pulse stream in response to the magnitude thereof in the range of 0 to ~00 KHz.
In accordance with another aspect of the invention, there is provided a voltage controlled oscillator producing a digital pu~se stream having a frequency variable in the range of 0 to ~00 Kl-lz i.n response to the output voltage of a switching regulator circuit as provided to an ou-tput voltage node comprising:
~L0 a A reference voltage source providing a known voltage at a refer-ence nocle;
b. An operationa.l amplifier connected to said reference node and said output voltage node for producing a. first signal in response -to the differ-cnce in the vol.ta.ge levels therebetween;
c. A pulse width modulator producing a digital pulse s-tream a.nd including a current mirror having a resistive input for controlling the crequency of sa.id digital pulse stream in response to the current applied thereto; and d. A transistor connected to amplify said first signal for applica.--tion to said resistive input.
In accordance with another a.spect of the inven-t;on~ there is provided a voltage controlled oscillator producing a cli.gital pulse strea.m having a frequency within the ra.nge of 0 to ~00 I~-lz -in response to devia--tion o:f an output voltage disposed at a first and second ou-tput terminals :Erom a predetermined voltage ~evel, comprising:
a A reference voltage source producing a Icnown vol-tage;
b. A first, second, third, and fourth resistors, said :Eirs-t and second resistors ~eing connected in series between said f;rs-t and second output terminals with said tirst resistor connected to said first output terminal and said second resistor connected to said second terminal forming an output voltage node between said first and second resis-tors, said third resistor being connected between sa.id reference voltage source and a refer-ence node, said ~ourth resistor connected between said reference node and said seconcl terminal;
c. An operational amplifier llaving its posit:ive inpu-t connected to said re:Eerence node a.nd its negative input connected to sa:id output voltage nocle for providing an output signa.l proportional to the clifference in poten-tial between saicl output voltage node and said reference node;
d. A transistor including a base, collector, and emitter, sa.id base connected to receive said output signal for providing an amplifiei output signal at said collector; and e. A pulse wid-th modulator opera.tively connected to receive said ampli~i.ed ou-tput signal for producing a digital pulse stream having a fre-quency in the range of 0 to ~00 Kllz in response to the magni-tude of said amplified output signal.
In accordance ~Yith a.nother aspez-t of the invention, there is provided a vol-ta.ge controlled oscillator producing a digi-ta]. pulse strea.m having a frequency in the range of 0 to ~00 ~Iz in response to it an output voltage of a switching regulator circuit comprising:
a. A first mea.ns ~or providing a reference voltage of a known level;
b. A second means operatively connected to receive said output volt-age and said reference voltage for producing an output signal in response thereto; and c. A pulse width modulator means receiving said output signal for producing said digital pulse stream in response to the magnitude of said output signal in the range of 0 to 400 ICrlz.
In accordance with another aspect of the invention, there is provided a voltage controlled oscilLator producing a digital pu:lse stream having a frequency in the ra.nge of 0 to ~on KHz in response to an output voltage, comprisi.ng:
a. A reference voltage means producing a knowrl voltage level;
b. An operational amplifier connected to receive said known voltage level and sa.id output voltage for producing an output signal in response to di~ferences therebetween by decreasing sa.id output signal as said output volta.ge increases toward said known voltage level; and c. A pulse width modulator for producing a digital pulse stream having a ~requency in the range of 0 to ~00 KHz in response to said output signal by decreasing the frequency of said digital pulse s-tream when said output signal increases and increasing the frequency of said digital pulse stream when said output signa.l decreases.
BRlEF DESCRIPTION OF THE DRA~INGS
Figure 1 îs a block dia.gram of a switching regulator circuit and a control apparatus utilizing the present invention; and Figure 2 is a schematic diagram of the voltage controlled oscillator of the present invention, DESCRIPTION OF T~E PREFERRED EMBODI~E~T
With reference to the drawings and in particular to Figure 1 thereof, a control apparatus 10 is connected to a switching regulator circuit 12. The control apparatus 10 includes an opera.tional amplifier 1~, a pulse width modulator 16, a recovery detector 18, a maximum frequellcy detector 20, and an SCR sequencer 22. Operational amplifier 14 and pulse width modulator 16 compri.se a voltage control]ed oscillator 25, Sw;.tch:ing regulator circuit 12 receives an unregulated DC input through lines 28 and 29 of some approp-riate voltage, Eor example, 286 volts DC, Although various regulated output voltages can be provided according to pa.rti.cular requirements of the circuits to which power is supplied by the switching regulator circuit 12, in the part-icular example a.s disclosed herein the output is 3,3 volts DC provided at output terminals 32 and 33 through lines 36 and 37, respectively. In other words, the regulated DC output on output terminals 32 and 33 presents a potential difference between the terminals of 3,3 volts DC. ~ power source 39 is connected through terminals 42 and 43 to lines 28 and 29, respectively, to provide the required unregulated DC power to switching regulator circuit 12.
The operational amplifier 14 is connected to the output vo~ta.ge present on lines 36 and 37, and, therefore, to the output terminals 32 a.nd 33 through lines 46 and 47~ respectively, The switching regula.tor circuit 12 is connected through lines 50 through 53 to recovery detector l~. The recovery .3~ 5~
detec-tor 18 is also connected to the s~itcll:ing regu:lator c:ircni-t l2 through line ~7.
The SCR sequencer 22 provides gating pulses to each o-f the SCRs within the sw;.tching regulator circuit 12 through multiline channel 5h ~ or a more cletai:led description ot the general flmctioning of switc}ling regulator circuits reference should be made to ~.S. E'a-tent No 4 1~2 23~ issued to Wilson et al. on February 27 1979 and ent:itled "lligh Curren-t Low Voltage Liquid Cooled Switching Regulator DC Power Supply".
Within control appara.tus 10 the output of the operational amplifier 1~ is connected through line 59 to pulse width modulator 16. The output of pulse width modulator 16 which comprises a digital pu]se stream is connected -to recovery detector 18 through line 61. The output of recovery detector 18 is connected through line 6~ as an input to the maximum frequency detector 20.
The input to SCR sequencer 22 is connected through line 66 to the output of maximum frequency detector 20. Lines 61 64 and 66 carry the digital pulse stream. The ].ocations of the recovery detector 18 and the maximum frequency detector 20 can be reversed as desired so that the maximum frequency detector 20 receives the output of pulse width modulator 16 and recovery detector 18 receives as its input the output of maximum frequency detector 20. If this arrangement were utilized recovery detector 18 ca.n have its output connected as an input to SCR sequencer 22.
The lines ~6 and ~7 which sense the output vol-tage of switching regu1.ator 12 can be connected to the output terminals 32 and .~, of switching regulator circuit 12 as shown in ~ S Pa.tent Applicati.on Ser:ia:l No 8n 6~2 by Genuit :t`iled on November 1 1979 a.nd entitled "Switching Regula-tor Circuit".
, ~' 'I'he SCR sequencer 22 provides gating pulses to each of -the indivi.duaI SCRs located within switching regulator circuit 12 through mult;l:ille channel 56, A more detailed discussion of the general opera.tion of -the con-trol apparatus and the switching regulator ci.rcuit 12 can be -found i.n -the copend:ing applica-tion by Nowell entitled "Control Apparatus for Switching Regulator Circuit", The sta.ble voltage controlled oscilla.tor 25 is required to operate over a wide range of frequenci.es beca.use of the varying :loads being appli.ed to switching regula-tor circuit 12, IJtilizing the voltage controlled oscilla~or25 as described herein it is possible to operate the switching regulator cir-cuit with loads varying from 1 percent to 100 percent of the maximum load, Thus, it is desirable to have the voltage controlled oscillator capable of producing a digital pulse stream which has an accura.te frequency over a range of frequencies of between 0 and ~00 K~lz in response to -the output voltage of switching regulator circuit lZ, The operational amplifier 14 and the pulse width modulator 16 which comprise the voltage controlled oscillator 25 are shown in detail in Figure 2. As discussed above, the output voltage of switching -regulator circuit 12 is received on lines ~6 and 47 by the volta.ge control]ed oscillator 25, Line ~7 is connected to resistors 116 and 117, a.nd capacitor 119, The other opposite end of resistor 116 is connected to a potentiometer 121, If the biasing does not need to be adjusted, then potentiometer 121 can be omitted. The other side o:E potentiometer 121 is connected through resistor 123 to line ~7. The mova.ble contact oE potentiometer ]2] :is connscted to a resistor 125, Resistor 117 is connected through another resistor 127 to line ~7, TLe side of capacitor 119 away from line ~6 is cormected through a res:istor l29 and capac.itor 131 -to line 47, The side of res:is-tor 125 away :Erom po-tentiometer 121 is connected intermediate capaci-tor 13~ and resistor 12~.
,~lso connectcd between resistor 129 and capacitor l3l are one end o:E res:istors 134 and 135. Line 138 connects the end of resistor 117 away from line ~6 a.nd one end of resi.stor 127 to the negat-ive input of comparator 14:L. The other side of resistor 127 is connectecl to l:ine 47. A certai.n known DC reEerence voltage is applied from a. voltage source 1~3 to l:ine 1~4.
I,ine 144 is connected to resistors 146 through 149, capacitor 152, and the :lo vo:ltage reference pin of pulse width modulator 16. Resis-tor 1~,6 at its end.
away from line 144 is connected to resistors 154, 155, and 156, and capa.citor 158. The other ends of capa.citor 158 a.nd resistor 156 away from resistor 1~6 are connected -to line 47. The other opposite end of resistor 154 is connected to the end of resistor 147 away ~rom line 144, to resistor 160, and to the nega.tive input o:E operational amplifier 163. The positive input of opera.-tional amplifier 163 is connected to the end o:E resistor 134 away from its connec-tion to resistor 129. The other opposite end of resistor 155 away from resistor 146 is connected to the positive input of operational amplifier 166.
The output of opera-tional amplitier lf,6 is connected to the base o:t a transistor 17~ a.nd to one end of a resistor 176. The emi-tter of transis-tor 17~ is connectecl to the other opposite end of resis-tor 176 and to a capa.-citor 178. The other side of capacitor 178 is connected through a resistor 181 to the negative input o~ operationa.l amplifier 166. The collector o~
tra.nsistor 174 is connected to line 59 and to one end of a resistor 169, If operational amplifier 166 is capable oE providing the proper si.gnal to line .~a~ 7~
59, transisto:r 17~ ca.n be el:i.minated if desired, The othe-r side of resistor 169 i.s connectecl to the outpu-t o~' operational amplifier l63 and to tlle s:ide of resis-tor l~8 awly from line 1~, Resistor 1~9 is connected to the noninverted input o:E the posi-tive input of the comparator within pulse width modula.tor 16 ancl to a resistor lS~. The end of resistor 18~ away irom resistor 1~9 is connec-ted to the positive inpu-t o:E comparator 1~1. a.nd to one end of a resistor 186, The other opposite end of res:istor 186 is connected to line ~7, The OUtpllt of comp-ara-tor 1~1 is connected to the emitter of tra.nsistor 17~ through a resistor 1~,9, As shown in Figure 2, cc,mpa.rator 141 produces an actuation signal which is applied to the emitter o~ transistor 17~ to provide proper biasing so that the output of operational a.mplifier 166 i.s amplifi.ed by the transistor 17~. 'l'he amplified output oE operativnal ampliEier 166 which is applied through line 59 to the resistive input of the current mirror pulse wid-th modulator 16. The greater the output of tra.nsistor 17~ the greater -the frequency of the digital pulse stream produced by a. pulse width modulator 16 as an output to line 61. I`he output to l.ine 61 has a frequency of the oscillator UUtpllt 200 of pulse width modulator 16 divided by two.
Operational amplifier 163 provides a feedback signal through resistor 169 to preven-t too rapid a change in the output of transistor 17~-in response to chaZIges in the output of opera.tional amplifier 166, Opera.-tional amplifier 166 a.lso has a feedba.c~.c loop -through resistor 176, capacitor 178 and resistor 181.
The output of pulse width modulator :16 to line 61 is utili~ed 7~i5 because -the particular op-tical coupler ~not shown) util;~ccl to sep.-rate the analog components from the digital components is unable to accommodate the :Eull range of 0 to 400 Kllz. A:Eter passing through the opt:ica:L coupler, the frequency is multipl:ied by two, The proper biasing o:E -the voltage produced by -the re:Eerence source 143 is provided by resistors 146 and 1!;5 through resistor 155 to the positive input of operational ampl.if:ier 166 at node 202, The ou-tput voltage of switclling regulator circuit 12 is prov.idecl to node 204 as cle-termined by resistors ll6 and 123 and potentiometer 121 througll resistor 135 to the negative input of opera.tiona.l amplifier 166.
The following designated integrated circuits have been found useful, but others can be utilized. Opera.tional amplifiers 163 and 166 are generally known as LM324. Comparator 141 is designa.ted as L~339, and pulse width mod-ulator is designated SG3524, In operation an increase in the load applied across output terminals 32 and 33 (Figure 1) tends to cause the output voltage on lines 46 and 47 to decrease. This voltage decrease is supplied through node 204 wi.th proper biasing to the negative input of operationa.l amplifier 166. Operational amplifier 166 responds by producing a.n Olltput which is ampliE-i.ed by transistor 174 and applied through line 59 to the resis-tive input of the current mirror of pulse width modulator 16. As the voltage decreases, the output of opera-tional amplifier 166 increases and therefore the voltage applied to the re-sistive terminal of -the current mirror of pulse width modulator lf through line 59 increases. This causes the :Erequency of the digital pulse stream produced by a pulse width modulator 16 to line 61 in its output to line 200 to have its f-requency increased, Comparator 141 provides a.n actuation signal for allowing tra.nsistor 174 to amplify the output of operational ampli:Eier 166. Opera-7(~;~
tional amplifier 163 which also receives -the voltage on node 204 through resistor 134 provides a delay through feedback to prevent too rapid a chcmge in the O~ltpUt of -transistor 174 applied through :I:ine 59, The output of opera-t-ional amplifier 163 is connected to the collector of tr<lnsistor l7 throllgh res;stor 169.
~ 1hereas the present invention has been descrihed in par-t;cular relati.on of the drawings atta.ched hereto, it should be unders-tood that other and :Eurther modifications, apart -from those silown or suggested herein, ma.y be made within the spirit and scope of this i.nvention.
The type of switching regulator circuit requiring such a wide range of fre-quencies of the digital pulse stream ram a voltage controlled oscillator is shown in ~. S. Patent No. 4,142,231 issued to Wilson et al. on February 27, 1979, and entitled "High Current Low Voltage Liquid Cooled Switching Regulator DC Power Supply". The improvement of the voltage controlled oscillator producing the digital pulse stream was required by an increase in the maximum frequency and therefore the firing rate per SCR. The increased firing rate per SCR requires improved control of the interval between the gating pulses to the SCRs to ensure that the SCRs recover fully prior to application of the next ga~e impulse to actua~e the SCR. If an ~CR is actuated prior to full recovery fron its prior actuation, the SCR
can fail catastrophically.
None of ~he prior constructions shows a voltage controlled oscillator which is caFable of producing a digital pulse stream having a frequency stable in ~he ran~e of 0 to 400 KHz.
~67~i;S
SUMM~RY OF THE INVENTION
A new and improved voltage controlled oscillator for utilization with a control circuit for a switching regulator circuit is shown herein. The output voltage is received by the voltage controlled oscillator. The predetermined voltage and ~he output voltage are inputs to an operational amplifier. The predetenmined voltage level is provided rom a reference source of stable DC voltage. The output of the operational amplifier varies in proportion to the deviation of the output voltage from the predetermined voltage level. Thus, the deviation of the output voltage from a predetermined voltage level is utilized by the operational amplifier ~o form a signal. This signal has its magnitude varied in propor~ion to the deviation of the output voltage from the predetermined voltage level.
The signal produced by the operational amplifier is amplified by a transis-tor ]ocated intermediate the operational amplifier and a pulse width mod~-la~or. The signal becomes an input to the resistive input of the current mirror of the pulse width modulator. m e source of reference voltage and the output voltage of the switching regulator circuits are provided to a comparator. The output of the comparator forms an actuation signal which is applied to ac~uate both the transistor a~d the operational amplifier. A
second operational amplifier is connected to the output voltage of the swi~ching regula~or circuit and to the reference voltage source. The second operational amplifier has a feedback loop comprisiny a capacitor and resistor with its output connected to the collector of ~he ~ransistor.
'~his second operational amplirier provides an initial current to the cur-rent mirror of the p~Lse width modulator durin~ startup~ m e collector is t,7C~
5202~53 ~he portion of the transistor connected to the resistive input of the cur-rent mirror of the pulse width modulator. The output signal produced by the- operational amplifier is amplified by the transistor to provide a well-defined current as an input to the resistive input of khe current mir-ror of pulse width modulator. The greater the signal generated by the operational amplifier, the greater the current flow to the current mirror of the pulse width modulator as amplified by the transistor. As the devia-tion between the predetermined voltage and the output voltage decreases, ~he magnitude of the signal produced by the operational amplifier decreases. The higher the current the greater the freq~ency of the diyital pulse stream produced by the pulse width modulator, the lesser the magni-tude of the signal produced by the operational amplifier as the signal from the operational amplifier decreases and therefore the decreased current from the collector of the transistor to the current mirror. As the current to the resistive input of the current mirror decreases, the frequency of digital pulse stream produced by the pulse width modulator decreases.
For example, if the load connected to the output of the switching regulator circuit increases, the output voltage tends to decrease. This decrease causes a deviation between the predetermined output voltage and the actual output voltage. The output signal of the operational amplifier increases a~d therefore the output of the transistor to the resistive input of the current mirror of the pulse width modulator increases which in turn increases the frequency of the digital pulse stream produced ~y the voltage controlled oscillator. The increased frequency of the digi~al pulse stream results in the SCRs being fired at a higher rate and, therefore, more ener-gy is transferred to the output of the switching regula-tor circuit to main-tain the output voltage at approxima.tely the predeterm:ined output voltage.
It is an advantage oi the present invention to provide a voltage controlled osci.llator capable of producing a. digita.l pulse stream having a stable frequency in the range of approximately 0 to ~00 Kllz.
It is a further advantage of the present invention to provide a voltage controlled oscillator utilizing a pulse width modulator capable of generati.ng a. stable digital pulse stream having a frequency in the ra.nge of 0 to ~00 KHz.
Allother advantage of the present invention is to provide a voltage controlled oscilkltor which responds to the devia.tion of an output voltage :Erom a predetermined voltage level by varying the frequency of the digital pulse strea.m produced within the range of 0 to ~00 KHz In a.ccordance with the present invention, there is provided a voltage controlled oscillator producing a di.gital pulse stream ilaving a frequency within the range of 0 to ~00 KHz, comprising:
a. Comparator connected to receive a reference voltage and the output voltage of a. switching regulator circuit for producing a first signal when said reference voltage is present;
b. An operational amplifier opera.tively connected to receive said first signa.l, said reference voltage, a.nd the output voltage of said switching regulator circuit producing a.t an output thereof a second signal havi.ng a. magnitude directly related to the deviation of sa:id output volta.ge from a determined volta.ge level; and _5_ 7'`~`~
c. A pulse width modulator operatively connec~:ed to receive said second signal at a resistor input of a current mirror therein for varying the frequency o-f said digital pulse stream in response to the magnitude thereof in the range of 0 to ~00 KHz.
In accordance with another aspect of the invention, there is provided a voltage controlled oscillator producing a digital pu~se stream having a frequency variable in the range of 0 to ~00 Kl-lz i.n response to the output voltage of a switching regulator circuit as provided to an ou-tput voltage node comprising:
~L0 a A reference voltage source providing a known voltage at a refer-ence nocle;
b. An operationa.l amplifier connected to said reference node and said output voltage node for producing a. first signal in response -to the differ-cnce in the vol.ta.ge levels therebetween;
c. A pulse width modulator producing a digital pulse s-tream a.nd including a current mirror having a resistive input for controlling the crequency of sa.id digital pulse stream in response to the current applied thereto; and d. A transistor connected to amplify said first signal for applica.--tion to said resistive input.
In accordance with another a.spect of the inven-t;on~ there is provided a voltage controlled oscillator producing a cli.gital pulse strea.m having a frequency within the ra.nge of 0 to ~00 I~-lz -in response to devia--tion o:f an output voltage disposed at a first and second ou-tput terminals :Erom a predetermined voltage ~evel, comprising:
a A reference voltage source producing a Icnown vol-tage;
b. A first, second, third, and fourth resistors, said :Eirs-t and second resistors ~eing connected in series between said f;rs-t and second output terminals with said tirst resistor connected to said first output terminal and said second resistor connected to said second terminal forming an output voltage node between said first and second resis-tors, said third resistor being connected between sa.id reference voltage source and a refer-ence node, said ~ourth resistor connected between said reference node and said seconcl terminal;
c. An operational amplifier llaving its posit:ive inpu-t connected to said re:Eerence node a.nd its negative input connected to sa:id output voltage nocle for providing an output signa.l proportional to the clifference in poten-tial between saicl output voltage node and said reference node;
d. A transistor including a base, collector, and emitter, sa.id base connected to receive said output signal for providing an amplifiei output signal at said collector; and e. A pulse wid-th modulator opera.tively connected to receive said ampli~i.ed ou-tput signal for producing a digital pulse stream having a fre-quency in the range of 0 to ~00 Kllz in response to the magni-tude of said amplified output signal.
In accordance ~Yith a.nother aspez-t of the invention, there is provided a vol-ta.ge controlled oscillator producing a digi-ta]. pulse strea.m having a frequency in the range of 0 to ~00 ~Iz in response to it an output voltage of a switching regulator circuit comprising:
a. A first mea.ns ~or providing a reference voltage of a known level;
b. A second means operatively connected to receive said output volt-age and said reference voltage for producing an output signal in response thereto; and c. A pulse width modulator means receiving said output signal for producing said digital pulse stream in response to the magnitude of said output signal in the range of 0 to 400 ICrlz.
In accordance with another aspect of the invention, there is provided a voltage controlled oscilLator producing a digital pu:lse stream having a frequency in the ra.nge of 0 to ~on KHz in response to an output voltage, comprisi.ng:
a. A reference voltage means producing a knowrl voltage level;
b. An operational amplifier connected to receive said known voltage level and sa.id output voltage for producing an output signal in response to di~ferences therebetween by decreasing sa.id output signal as said output volta.ge increases toward said known voltage level; and c. A pulse width modulator for producing a digital pulse stream having a ~requency in the range of 0 to ~00 KHz in response to said output signal by decreasing the frequency of said digital pulse s-tream when said output signal increases and increasing the frequency of said digital pulse stream when said output signa.l decreases.
BRlEF DESCRIPTION OF THE DRA~INGS
Figure 1 îs a block dia.gram of a switching regulator circuit and a control apparatus utilizing the present invention; and Figure 2 is a schematic diagram of the voltage controlled oscillator of the present invention, DESCRIPTION OF T~E PREFERRED EMBODI~E~T
With reference to the drawings and in particular to Figure 1 thereof, a control apparatus 10 is connected to a switching regulator circuit 12. The control apparatus 10 includes an opera.tional amplifier 1~, a pulse width modulator 16, a recovery detector 18, a maximum frequellcy detector 20, and an SCR sequencer 22. Operational amplifier 14 and pulse width modulator 16 compri.se a voltage control]ed oscillator 25, Sw;.tch:ing regulator circuit 12 receives an unregulated DC input through lines 28 and 29 of some approp-riate voltage, Eor example, 286 volts DC, Although various regulated output voltages can be provided according to pa.rti.cular requirements of the circuits to which power is supplied by the switching regulator circuit 12, in the part-icular example a.s disclosed herein the output is 3,3 volts DC provided at output terminals 32 and 33 through lines 36 and 37, respectively. In other words, the regulated DC output on output terminals 32 and 33 presents a potential difference between the terminals of 3,3 volts DC. ~ power source 39 is connected through terminals 42 and 43 to lines 28 and 29, respectively, to provide the required unregulated DC power to switching regulator circuit 12.
The operational amplifier 14 is connected to the output vo~ta.ge present on lines 36 and 37, and, therefore, to the output terminals 32 a.nd 33 through lines 46 and 47~ respectively, The switching regula.tor circuit 12 is connected through lines 50 through 53 to recovery detector l~. The recovery .3~ 5~
detec-tor 18 is also connected to the s~itcll:ing regu:lator c:ircni-t l2 through line ~7.
The SCR sequencer 22 provides gating pulses to each o-f the SCRs within the sw;.tching regulator circuit 12 through multiline channel 5h ~ or a more cletai:led description ot the general flmctioning of switc}ling regulator circuits reference should be made to ~.S. E'a-tent No 4 1~2 23~ issued to Wilson et al. on February 27 1979 and ent:itled "lligh Curren-t Low Voltage Liquid Cooled Switching Regulator DC Power Supply".
Within control appara.tus 10 the output of the operational amplifier 1~ is connected through line 59 to pulse width modulator 16. The output of pulse width modulator 16 which comprises a digital pu]se stream is connected -to recovery detector 18 through line 61. The output of recovery detector 18 is connected through line 6~ as an input to the maximum frequency detector 20.
The input to SCR sequencer 22 is connected through line 66 to the output of maximum frequency detector 20. Lines 61 64 and 66 carry the digital pulse stream. The ].ocations of the recovery detector 18 and the maximum frequency detector 20 can be reversed as desired so that the maximum frequency detector 20 receives the output of pulse width modulator 16 and recovery detector 18 receives as its input the output of maximum frequency detector 20. If this arrangement were utilized recovery detector 18 ca.n have its output connected as an input to SCR sequencer 22.
The lines ~6 and ~7 which sense the output vol-tage of switching regu1.ator 12 can be connected to the output terminals 32 and .~, of switching regulator circuit 12 as shown in ~ S Pa.tent Applicati.on Ser:ia:l No 8n 6~2 by Genuit :t`iled on November 1 1979 a.nd entitled "Switching Regula-tor Circuit".
, ~' 'I'he SCR sequencer 22 provides gating pulses to each of -the indivi.duaI SCRs located within switching regulator circuit 12 through mult;l:ille channel 56, A more detailed discussion of the general opera.tion of -the con-trol apparatus and the switching regulator ci.rcuit 12 can be -found i.n -the copend:ing applica-tion by Nowell entitled "Control Apparatus for Switching Regulator Circuit", The sta.ble voltage controlled oscilla.tor 25 is required to operate over a wide range of frequenci.es beca.use of the varying :loads being appli.ed to switching regula-tor circuit 12, IJtilizing the voltage controlled oscilla~or25 as described herein it is possible to operate the switching regulator cir-cuit with loads varying from 1 percent to 100 percent of the maximum load, Thus, it is desirable to have the voltage controlled oscillator capable of producing a digital pulse stream which has an accura.te frequency over a range of frequencies of between 0 and ~00 K~lz in response to -the output voltage of switching regulator circuit lZ, The operational amplifier 14 and the pulse width modulator 16 which comprise the voltage controlled oscillator 25 are shown in detail in Figure 2. As discussed above, the output voltage of switching -regulator circuit 12 is received on lines ~6 and 47 by the volta.ge control]ed oscillator 25, Line ~7 is connected to resistors 116 and 117, a.nd capacitor 119, The other opposite end of resistor 116 is connected to a potentiometer 121, If the biasing does not need to be adjusted, then potentiometer 121 can be omitted. The other side o:E potentiometer 121 is connected through resistor 123 to line ~7. The mova.ble contact oE potentiometer ]2] :is connscted to a resistor 125, Resistor 117 is connected through another resistor 127 to line ~7, TLe side of capacitor 119 away from line ~6 is cormected through a res:istor l29 and capac.itor 131 -to line 47, The side of res:is-tor 125 away :Erom po-tentiometer 121 is connected intermediate capaci-tor 13~ and resistor 12~.
,~lso connectcd between resistor 129 and capacitor l3l are one end o:E res:istors 134 and 135. Line 138 connects the end of resistor 117 away from line ~6 a.nd one end of resi.stor 127 to the negat-ive input of comparator 14:L. The other side of resistor 127 is connectecl to l:ine 47. A certai.n known DC reEerence voltage is applied from a. voltage source 1~3 to l:ine 1~4.
I,ine 144 is connected to resistors 146 through 149, capacitor 152, and the :lo vo:ltage reference pin of pulse width modulator 16. Resis-tor 1~,6 at its end.
away from line 144 is connected to resistors 154, 155, and 156, and capa.citor 158. The other ends of capa.citor 158 a.nd resistor 156 away from resistor 1~6 are connected -to line 47. The other opposite end of resistor 154 is connected to the end of resistor 147 away ~rom line 144, to resistor 160, and to the nega.tive input o:E operational amplifier 163. The positive input of opera.-tional amplifier 163 is connected to the end o:E resistor 134 away from its connec-tion to resistor 129. The other opposite end of resistor 155 away from resistor 146 is connected to the positive input of operational amplifier 166.
The output of opera-tional amplitier lf,6 is connected to the base o:t a transistor 17~ a.nd to one end of a resistor 176. The emi-tter of transis-tor 17~ is connectecl to the other opposite end of resis-tor 176 and to a capa.-citor 178. The other side of capacitor 178 is connected through a resistor 181 to the negative input o~ operationa.l amplifier 166. The collector o~
tra.nsistor 174 is connected to line 59 and to one end of a resistor 169, If operational amplifier 166 is capable oE providing the proper si.gnal to line .~a~ 7~
59, transisto:r 17~ ca.n be el:i.minated if desired, The othe-r side of resistor 169 i.s connectecl to the outpu-t o~' operational amplifier l63 and to tlle s:ide of resis-tor l~8 awly from line 1~, Resistor 1~9 is connected to the noninverted input o:E the posi-tive input of the comparator within pulse width modula.tor 16 ancl to a resistor lS~. The end of resistor 18~ away irom resistor 1~9 is connec-ted to the positive inpu-t o:E comparator 1~1. a.nd to one end of a resistor 186, The other opposite end of res:istor 186 is connected to line ~7, The OUtpllt of comp-ara-tor 1~1 is connected to the emitter of tra.nsistor 17~ through a resistor 1~,9, As shown in Figure 2, cc,mpa.rator 141 produces an actuation signal which is applied to the emitter o~ transistor 17~ to provide proper biasing so that the output of operational a.mplifier 166 i.s amplifi.ed by the transistor 17~. 'l'he amplified output oE operativnal ampliEier 166 which is applied through line 59 to the resistive input of the current mirror pulse wid-th modulator 16. The greater the output of tra.nsistor 17~ the greater -the frequency of the digital pulse stream produced by a. pulse width modulator 16 as an output to line 61. I`he output to l.ine 61 has a frequency of the oscillator UUtpllt 200 of pulse width modulator 16 divided by two.
Operational amplifier 163 provides a feedback signal through resistor 169 to preven-t too rapid a change in the output of transistor 17~-in response to chaZIges in the output of opera.tional amplifier 166, Opera.-tional amplifier 166 a.lso has a feedba.c~.c loop -through resistor 176, capacitor 178 and resistor 181.
The output of pulse width modulator :16 to line 61 is utili~ed 7~i5 because -the particular op-tical coupler ~not shown) util;~ccl to sep.-rate the analog components from the digital components is unable to accommodate the :Eull range of 0 to 400 Kllz. A:Eter passing through the opt:ica:L coupler, the frequency is multipl:ied by two, The proper biasing o:E -the voltage produced by -the re:Eerence source 143 is provided by resistors 146 and 1!;5 through resistor 155 to the positive input of operational ampl.if:ier 166 at node 202, The ou-tput voltage of switclling regulator circuit 12 is prov.idecl to node 204 as cle-termined by resistors ll6 and 123 and potentiometer 121 througll resistor 135 to the negative input of opera.tiona.l amplifier 166.
The following designated integrated circuits have been found useful, but others can be utilized. Opera.tional amplifiers 163 and 166 are generally known as LM324. Comparator 141 is designa.ted as L~339, and pulse width mod-ulator is designated SG3524, In operation an increase in the load applied across output terminals 32 and 33 (Figure 1) tends to cause the output voltage on lines 46 and 47 to decrease. This voltage decrease is supplied through node 204 wi.th proper biasing to the negative input of operationa.l amplifier 166. Operational amplifier 166 responds by producing a.n Olltput which is ampliE-i.ed by transistor 174 and applied through line 59 to the resis-tive input of the current mirror of pulse width modulator 16. As the voltage decreases, the output of opera-tional amplifier 166 increases and therefore the voltage applied to the re-sistive terminal of -the current mirror of pulse width modulator lf through line 59 increases. This causes the :Erequency of the digital pulse stream produced by a pulse width modulator 16 to line 61 in its output to line 200 to have its f-requency increased, Comparator 141 provides a.n actuation signal for allowing tra.nsistor 174 to amplify the output of operational ampli:Eier 166. Opera-7(~;~
tional amplifier 163 which also receives -the voltage on node 204 through resistor 134 provides a delay through feedback to prevent too rapid a chcmge in the O~ltpUt of -transistor 174 applied through :I:ine 59, The output of opera-t-ional amplifier 163 is connected to the collector of tr<lnsistor l7 throllgh res;stor 169.
~ 1hereas the present invention has been descrihed in par-t;cular relati.on of the drawings atta.ched hereto, it should be unders-tood that other and :Eurther modifications, apart -from those silown or suggested herein, ma.y be made within the spirit and scope of this i.nvention.
Claims (9)
- Claim 1. A voltage controlled oscillator producing a digital pulse stream having a frequency within the range of 0 to 400 KHz, comprising:
a. Comparator connected to receive a reference voltage and the output voltage of a switching regulator circuit for producing a first signal when said reference voltage is present;
b. An operational amplifier operatively connected to receive said first signal, said reference voltage, and the output voltage of said switching regulator circuit producing at an output thereof a second signal having a magnitude directly related to the deviation of said output voltage from a determined voltage level; and c. A pulse width modulator operatively connected to receive said second signal at a resistor input of a current mirror therein for varying the frequency of said digital pulse stream in response to the magnitude thereof in the range of 0 to 400 KHz. - Claim 2. Voltage controlled oscillator as set forth in claim 1 including a transistor located intermediate said operational amplifier and said pulse width modulator for amplifying said second signal, said transistor receiving said first signal at its emitter for actuation, said transistor having its base connected to said operational amplifier and its collector connected to said pulse width modulator.
- Claim 3. Voltage controlled oscillator as set forth in claim 1 wherein said operational amplifier increases the magnitude of said first signal when said output voltage is below said reference voltage and decreases the magnitude of said first signal when said output voltage is above said ref-erence voltage.
- Claim 4. A voltage controlled oscillator producing a digital pulse stream having a frequency variable in the range of 0 to 400 KHz in response to the output voltage of a switching regulator circuit as provided to an output voltage node comprising:
a. A reference voltage source providing a known voltage at a refer-ence node;
b. An operational amplifier connected to said reference node and said output voltage node for producing a first signal in response to the differ-ence in the voltage levels therebetween;
c. A pulse width modulator producing a digital pulse stream and including a current mirror having a resistive input for controlling the freguency of said digital pulse stream in response to the current applied thereto; and d. A transistor connected to amplify said first signal for applica-tion to said resistive input. - Claim 5. Voltage controlled oscillator as set forth in claim 4 wherein said output voltage provided at a first and second terminals and including a first, second, third and fourth resistors, said first resistor connected between said output voltage node and said first terminal, said second resistor connected between said output voltage node and said second termi-nal, said third resistor connected between said reference voltage source and said reference node, and said fourth resistor connected between said reference node are said second terminal for providing properly biased vol-tages to said operational amplifier.
- Claim 6. Voltage controlled oscillator as set forth in claim 4 wherein transistor includes a base, a collector, and an emitter, and including a comparator connected to said reference voltage for source and said output voltage for providing an actuation signal to said emitter to allow said transistor to amplify said first signal applied to said base while said reference voltage source is providing voltage, said collector being connected to said resistive input.
- Claim 7. A voltage controlld oscillator producing a digital pulse stream having a frequency within the range of 0 to 400 KHz in response to devia-tion of an output voltage disposed at a first and second output terminals from a predetermined voltage level, comprising:
a. A reference voltage source producing a known voltage;
b. A first, second, third, and fourth resistors, said first and second resistors being connected in series between said first and second output terminals with said first resistor connected to said first output terminal are said second resistor connected to said second terminal forming an output voltage node between said first a second resistors, said third resistor being connected between said reference voltage source and a refer-ence node, said fourth resistor connected between said reference node and said second terminal;
c. An operational amplifier having its positive input connected to said reference node and its negative input connected to said output voltage node for providing an output signal proportional to the difference in potential between said output voltage node and said reference node;
d. A transistor including a base, collector, and emitter, said base connected to receive said output signal for providing an amplified output signal as said collector; and e. A pulse width modulator operatively connected to receive said amplified output signal for producing a digital pulse stream having a fre-quency in the range of 0 to 400 KHz in response to the magnitude of said amplified output signal. - Claim 8. A voltage controlled oscillator producing a digital pulse stream having a frequency in the range of 0 to 400 KHz in response to it an output voltage of a switching regulator circuit comprising:
a. A first means for providing a reference voltage of a known level;
b. A second means operatively connected to receive said output volt-age and said reference voltage for producing an output signal in response thereto; and c. A pulse width modulator means receiving said output signal for producing said digital pulse stream in response to the magnitude of said output signal in the range of 0 to 400 KHz. - Claim 9 A voltage controlled oscillator producing a digital pulse stream having a frequency in the range of 0 to 400 KHz in response to an output voltage, comprising:
a. A reference voltage means producing a known voltage level;
b. An operational amplifier connected to receive said known voltage level and said output voltage for producing an output signal in response to differences therebetween by decreasing said output signal as said output voltage increases toward said known voltage level; and c. A pulse width modulator for producing a digital pulse stream having a frequency in the range of 0 to 400 KHZ in response to said output signal by decreasing the frequency of said digital pulse stream when said output signal increases and increasing the frequency of said digital pulse stream when said output signal decreases.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19111180A | 1980-09-26 | 1980-09-26 | |
| US191,111 | 1988-05-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1186755A true CA1186755A (en) | 1985-05-07 |
Family
ID=22704188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386729A Expired CA1186755A (en) | 1980-09-26 | 1981-09-25 | Voltage controlled oscillator |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5787231A (en) |
| AU (1) | AU7570181A (en) |
| CA (1) | CA1186755A (en) |
| MX (1) | MX151638A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4968952A (en) * | 1989-06-02 | 1990-11-06 | Motorola, Inc. | Voltage control oscillator with automatic current control |
-
1981
- 1981-09-25 CA CA000386729A patent/CA1186755A/en not_active Expired
- 1981-09-25 MX MX18932281A patent/MX151638A/en unknown
- 1981-09-26 JP JP56152835A patent/JPS5787231A/en active Pending
- 1981-09-28 AU AU75701/81A patent/AU7570181A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU7570181A (en) | 1982-04-01 |
| JPS5787231A (en) | 1982-05-31 |
| MX151638A (en) | 1985-01-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4316242A (en) | Wide input range, transient-immune regulated flyback switching power supply | |
| US2968738A (en) | Regulated source of alternating or direct current | |
| US2791739A (en) | Circuit arrangement for converting a lower d. c. voltage into a higher d. c. voltage | |
| CA1246141A (en) | Boost feedforward pulse width modulation regulator | |
| US3383584A (en) | Solid state switching regulator circuit | |
| US3863140A (en) | Regulated power supply including forward feed | |
| US2850694A (en) | Current supply apparatus for load voltage regulation | |
| JPS61191263A (en) | Back boost switching regulator | |
| US3213351A (en) | Firing pulse generating circuit for solid state controlled rectifiers | |
| US4001665A (en) | High efficiency power supply having a reactive buck automatic d.c. voltage regulator | |
| US4961006A (en) | Inductively loaded switching transistor circuit | |
| US3067378A (en) | Transistor converter | |
| CA1063171A (en) | Control circuit arrangement for generating a control signal for a voltage converter | |
| US11874680B2 (en) | Power supply with integrated voltage regulator and current limiter and method | |
| US4648016A (en) | Blocking oscillator switched mode power supply | |
| US2932783A (en) | Voltage regulated power supply | |
| US3214599A (en) | Voltage regulator for d.c. generator | |
| US4056734A (en) | Compensated base drive circuit to regulate saturated transistor current gain | |
| US3562668A (en) | Variable load controlled blocking oscillator power converter | |
| US5936446A (en) | PWM variable voltage load driver with peak voltage limitation | |
| US3600667A (en) | Power supply having parallel dissipative and switching regulators | |
| CA1186755A (en) | Voltage controlled oscillator | |
| US4263644A (en) | Current limiter for switched DC-to-DC converter | |
| US4245294A (en) | Power supply providing constant power output | |
| US3284694A (en) | Voltage regulating system for an electrical generator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |