CA1085921A - Method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the method - Google Patents
Method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the methodInfo
- Publication number
- CA1085921A CA1085921A CA264,449A CA264449A CA1085921A CA 1085921 A CA1085921 A CA 1085921A CA 264449 A CA264449 A CA 264449A CA 1085921 A CA1085921 A CA 1085921A
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- temperature
- voltage source
- value
- actual
- 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
- 238000000034 method Methods 0.000 title claims description 8
- 230000001419 dependent effect Effects 0.000 claims abstract description 14
- 230000001105 regulatory effect Effects 0.000 claims abstract description 12
- 230000003321 amplification Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 1
- 238000012886 linear function Methods 0.000 description 1
Landscapes
- Continuous-Control Power Sources That Use Transistors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In a stabilized voltage source having an actual-value voltage gauge which is temperature dependent, the overall temperature stability of the voltage source is improved by providing a reference-value voltage with an adjustable temperature coef-ficient, said temperature coefficient being so adjusted that it substantially compensates for the temperature dependence of the actual-value voltage gauge within the temperature range used. The reference voltage having an adjustable temperature coefficient is preferably obtained by combining a first voltage which is essentially independent of temperature with a second voltage being strongly dependent on temperature, the degree of mutual influence of said combined voltages being regulated to adjust said temperature coefficient.
In a stabilized voltage source having an actual-value voltage gauge which is temperature dependent, the overall temperature stability of the voltage source is improved by providing a reference-value voltage with an adjustable temperature coef-ficient, said temperature coefficient being so adjusted that it substantially compensates for the temperature dependence of the actual-value voltage gauge within the temperature range used. The reference voltage having an adjustable temperature coefficient is preferably obtained by combining a first voltage which is essentially independent of temperature with a second voltage being strongly dependent on temperature, the degree of mutual influence of said combined voltages being regulated to adjust said temperature coefficient.
Description
1~8S9Z~
OUTOKUMPU OY, Ou tokumpu A method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the method The present invention relates to a method of improving the temperature stability of a voltage source when the voltage source has a temperature-dependent gauge for the actual-value voltage. The invention also relates to a voltage source for carrying out the method.
Resistive voltage dividers are generally used as actual-value gauges in voltage sources. Especially in high-voltage applications the high-voltage side resistor of a voltage source will have a resistance of hundreds of megaohms, if it is desired to use a small-sized gauge which dissipates little power. The best high-ohm, high-voltage resistors available have temperature coefficients of the order of + 100 ppm/K.
It also follows from the above that the temperature coefficients of known voltage sources provided with high-voltage resistors of the said type are of the same order as those of the high-voltage resistors in question, i.e., the voltage sources are not so temperature-stable as would be desirable.
The object of the present invention is to eliminate the said . : .: ..
.: . .
:
:.
,. ''"' '-: :
lQ~59Zl problem and to provide a voltage source, especially for high voltages, the voltage source having a considerably improved temperature stability.
If good electronic components and large control-circuit loop amplification is used, the temperature stability of a voltage source can be considered to be determined only on the basis of the stabilities of the actual-value gauge and the reference-value voltage source.
As was noted above, high-ohm resistors with great stability are not available. Since, however, the temperature coefficient of such resistors is constant, the present invention is based on compensation of the said temperature coefficient by means of a reference-value voltage dependent on the te~perature in a corresponding manner; thereby a voltage source is obtained in which the temperature coefficient of the output voltage is considerably better, i.e., smaller than that of the gauge used.
In accordance with the invention there is provided in a stabilized voltage source of the type having a temperature-dependent actual voltage gauge which senses the output voltage of the voltage source, a reference value circuit providing a reference value voltage, said reference value circuit comprising a temperature-stable first voltage source and a second voltage source which is strongly dependent on temperature, means for summing the voltage outputs of said first and second voltage source of said reference value circuit, and means for regulating the output voltage of at least one of said first and second voltage sources to control the reference value voltage for regulating the temperature coefficient of the reference value voltage to compensate for temperature dependence of the actual value voltage~
In accordance with another aspect of the invention there is provided a method of impr~v m g the temperature stability of a voltage source having a ., 1(J8592~
temperature-dependent actual-value voltage gauge, which comprises: providing a reference-value voltage for said voltage source by means of a reference-value voltage circuit having an adjustable temperature coefficient; and adjusting said adjustable tem~erature coefficient to produce a reference-value voltage which compensates for the temperature dependence of said actual-value voltage gauge, said reference value voltage being produced by summing the voltage outputs of a first voltage source independent of temperature and a second voltage source strongly dependent on temperature, and including regulating the output voltage of at least one of said first and second voltage sources before said summing to adjust the reference-value voltage.
Figure 1 shows a typical block diagram of the voltage source, and Figure 2 shows, partly diagrammatically, the circuit which forms the reference-value voltage of the voltage source.
If it is assumed that the direct-voltage amplification A of the differential amplifier 4 is very large, it can be thought that Vr ~ Va = (1) The following dependence prevails between the initial voltage VL and the actual value Va;
VL a ~ Va -2a-:
- : :
:
lV859Zl Since Va = Vr, VL = K V (3) a r The gauge constant Ka and the actual-value voltage are functions of the temperature T.
It is assumed that Ka and Vr are both linear functions of the temperature.
Ka(T) = Pa (1 + Ca ) r(T) Pr Vz (1 + CrT) (5) Pa, Pr, Vz are constant coefficients. ~
Ca, Cr are the temperature coefficients of the actual-value ~ -gauge 2 and the reference-value voltage.
T is normalized temperature.
The conditions on which the differential of the initial voltage in regard to the temperature T is zero are observed below:
VL = Ka(T) vr( avL aK (T) av (T) L dT = a . V (T).dT + K (T) dT =
a T a T r a a T
a r z a ( CrT) + Cr (1 + CaT)] dT (6) When temperature T = O
dVL (O) = Pa Pr Vz (Ca + Cr) If it is now desired that dVL(O) = O, Ca + Cr = i-e- Ca = ~Cr is obtained (note: dT ~ O).
7 - - - ' ' '' . . . '. :
' " ' ' ' ..
.
.
' , 4 10859Z~
The obtained result is placed in the expression (6) for dVL, and L(T) 2 Pa Pr Vz Ca T dT (7) is obtained.
Within a wider temperature range ~T
L T-O Pa Pr Vz Ca2 T dT =
_ p . P . V C 2 (~T)2 (8) is valid.
Since VL is at temperature T = O
VL(O) = Pa Pr z the temperature coefficient obtained for the initial voltage i5 ~V
VL(O)aT = ~ Ca ~T (9) In an uncompensated case (when Cr = O) .
~V
VL(O)~T a (10) is obtained.
Example It is assumed that the temperature coefficient of the actual-value gauge Ca = 100 ppm/K and the extent of its operation temperature range (~T) is 50 K.
In an uncompensated case l~VL
= 100 ppm/K
VL(O)~T
is obtained according to Equation (10).
.
- ,:;
.
` 10859Zl In a compensated case QvL = -(100 10 6/K) 50 K = 0.5 ppm/K
VL(O)~T
is obtained according to Equation (9).
It is observed that considerable improvement is achieved by the compensation.
If the voltage source can be regulated, the regulation must be performed in such a manner that in the expression for the reference-value voltage Vr Pr Vz ~ CrT) (Vz = constant) the control affects the coefficient Pr; otherwise, different temperature coefficients are obtained with different initial voltages.
It has been shown above that, if the temperature coefficient of the reference-value voltage source used can be regulated so that Cr = - Ca (Ca can be measured), a considerable improvement is achieved in the stability of the voltage source. Fig. 2 shows one circuit arrangement which has the above characteristic. -In the wiring, the temperature dependence of the base emitter ~ voltage VBE of the transistor T is utilized; within the operation temperature range this dependence can be considered very linear.
The transistor T forms a reconnection for the differential amplifier Zl, in which case the base and the collector of the transistor have been linked together at the input of the amplifier in the manner indicated in the figure. The output of the amplifier Zl is passed through the voltage divider Rs, Rs into one input of the amplifier Z2 and through the control resistor RT into the other input; the output voltage V(T) of the amplifier Z2 can be regulated by regulating the resistor RT.
The stable voltage Vz and the temperature-dependent voltage V(T) are summed by means of the resistors R. The sum voltage is multiplied by the coefficient Pr; by changing Pr the initial voltage Vr(T) can be regulated without changing the temperature coefficient. By means of the trimmer RT serving as the bridge resistor the temperature coefficient of the voltage Vr(T) is adjusted to the desired value.
~ .
~- --., ' .
, ~ . .
-' ,, : , . .
OUTOKUMPU OY, Ou tokumpu A method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the method The present invention relates to a method of improving the temperature stability of a voltage source when the voltage source has a temperature-dependent gauge for the actual-value voltage. The invention also relates to a voltage source for carrying out the method.
Resistive voltage dividers are generally used as actual-value gauges in voltage sources. Especially in high-voltage applications the high-voltage side resistor of a voltage source will have a resistance of hundreds of megaohms, if it is desired to use a small-sized gauge which dissipates little power. The best high-ohm, high-voltage resistors available have temperature coefficients of the order of + 100 ppm/K.
It also follows from the above that the temperature coefficients of known voltage sources provided with high-voltage resistors of the said type are of the same order as those of the high-voltage resistors in question, i.e., the voltage sources are not so temperature-stable as would be desirable.
The object of the present invention is to eliminate the said . : .: ..
.: . .
:
:.
,. ''"' '-: :
lQ~59Zl problem and to provide a voltage source, especially for high voltages, the voltage source having a considerably improved temperature stability.
If good electronic components and large control-circuit loop amplification is used, the temperature stability of a voltage source can be considered to be determined only on the basis of the stabilities of the actual-value gauge and the reference-value voltage source.
As was noted above, high-ohm resistors with great stability are not available. Since, however, the temperature coefficient of such resistors is constant, the present invention is based on compensation of the said temperature coefficient by means of a reference-value voltage dependent on the te~perature in a corresponding manner; thereby a voltage source is obtained in which the temperature coefficient of the output voltage is considerably better, i.e., smaller than that of the gauge used.
In accordance with the invention there is provided in a stabilized voltage source of the type having a temperature-dependent actual voltage gauge which senses the output voltage of the voltage source, a reference value circuit providing a reference value voltage, said reference value circuit comprising a temperature-stable first voltage source and a second voltage source which is strongly dependent on temperature, means for summing the voltage outputs of said first and second voltage source of said reference value circuit, and means for regulating the output voltage of at least one of said first and second voltage sources to control the reference value voltage for regulating the temperature coefficient of the reference value voltage to compensate for temperature dependence of the actual value voltage~
In accordance with another aspect of the invention there is provided a method of impr~v m g the temperature stability of a voltage source having a ., 1(J8592~
temperature-dependent actual-value voltage gauge, which comprises: providing a reference-value voltage for said voltage source by means of a reference-value voltage circuit having an adjustable temperature coefficient; and adjusting said adjustable tem~erature coefficient to produce a reference-value voltage which compensates for the temperature dependence of said actual-value voltage gauge, said reference value voltage being produced by summing the voltage outputs of a first voltage source independent of temperature and a second voltage source strongly dependent on temperature, and including regulating the output voltage of at least one of said first and second voltage sources before said summing to adjust the reference-value voltage.
Figure 1 shows a typical block diagram of the voltage source, and Figure 2 shows, partly diagrammatically, the circuit which forms the reference-value voltage of the voltage source.
If it is assumed that the direct-voltage amplification A of the differential amplifier 4 is very large, it can be thought that Vr ~ Va = (1) The following dependence prevails between the initial voltage VL and the actual value Va;
VL a ~ Va -2a-:
- : :
:
lV859Zl Since Va = Vr, VL = K V (3) a r The gauge constant Ka and the actual-value voltage are functions of the temperature T.
It is assumed that Ka and Vr are both linear functions of the temperature.
Ka(T) = Pa (1 + Ca ) r(T) Pr Vz (1 + CrT) (5) Pa, Pr, Vz are constant coefficients. ~
Ca, Cr are the temperature coefficients of the actual-value ~ -gauge 2 and the reference-value voltage.
T is normalized temperature.
The conditions on which the differential of the initial voltage in regard to the temperature T is zero are observed below:
VL = Ka(T) vr( avL aK (T) av (T) L dT = a . V (T).dT + K (T) dT =
a T a T r a a T
a r z a ( CrT) + Cr (1 + CaT)] dT (6) When temperature T = O
dVL (O) = Pa Pr Vz (Ca + Cr) If it is now desired that dVL(O) = O, Ca + Cr = i-e- Ca = ~Cr is obtained (note: dT ~ O).
7 - - - ' ' '' . . . '. :
' " ' ' ' ..
.
.
' , 4 10859Z~
The obtained result is placed in the expression (6) for dVL, and L(T) 2 Pa Pr Vz Ca T dT (7) is obtained.
Within a wider temperature range ~T
L T-O Pa Pr Vz Ca2 T dT =
_ p . P . V C 2 (~T)2 (8) is valid.
Since VL is at temperature T = O
VL(O) = Pa Pr z the temperature coefficient obtained for the initial voltage i5 ~V
VL(O)aT = ~ Ca ~T (9) In an uncompensated case (when Cr = O) .
~V
VL(O)~T a (10) is obtained.
Example It is assumed that the temperature coefficient of the actual-value gauge Ca = 100 ppm/K and the extent of its operation temperature range (~T) is 50 K.
In an uncompensated case l~VL
= 100 ppm/K
VL(O)~T
is obtained according to Equation (10).
.
- ,:;
.
` 10859Zl In a compensated case QvL = -(100 10 6/K) 50 K = 0.5 ppm/K
VL(O)~T
is obtained according to Equation (9).
It is observed that considerable improvement is achieved by the compensation.
If the voltage source can be regulated, the regulation must be performed in such a manner that in the expression for the reference-value voltage Vr Pr Vz ~ CrT) (Vz = constant) the control affects the coefficient Pr; otherwise, different temperature coefficients are obtained with different initial voltages.
It has been shown above that, if the temperature coefficient of the reference-value voltage source used can be regulated so that Cr = - Ca (Ca can be measured), a considerable improvement is achieved in the stability of the voltage source. Fig. 2 shows one circuit arrangement which has the above characteristic. -In the wiring, the temperature dependence of the base emitter ~ voltage VBE of the transistor T is utilized; within the operation temperature range this dependence can be considered very linear.
The transistor T forms a reconnection for the differential amplifier Zl, in which case the base and the collector of the transistor have been linked together at the input of the amplifier in the manner indicated in the figure. The output of the amplifier Zl is passed through the voltage divider Rs, Rs into one input of the amplifier Z2 and through the control resistor RT into the other input; the output voltage V(T) of the amplifier Z2 can be regulated by regulating the resistor RT.
The stable voltage Vz and the temperature-dependent voltage V(T) are summed by means of the resistors R. The sum voltage is multiplied by the coefficient Pr; by changing Pr the initial voltage Vr(T) can be regulated without changing the temperature coefficient. By means of the trimmer RT serving as the bridge resistor the temperature coefficient of the voltage Vr(T) is adjusted to the desired value.
~ .
~- --., ' .
, ~ . .
-' ,, : , . .
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a stabilized voltage source of the type having a temperature-dependent actual voltage gauge which senses the output voltage of the voltage source, a reference value circuit providing a reference value voltage, said reference value circuit comprising a temperature-stable first voltage source and a second voltage source which is strongly dependent on temperature, means for summing the voltage outputs of said first and second voltage source of said reference value circuit, and means for regulating the output voltage of at least one of said first and second voltage sources to control the reference value voltage for regulating the temperature coefficient of the reference value voltage to compensate for temperature dependence of the actual value voltage.
2. A stabilized voltage source according to claim 1, wherein said second voltage source which is strongly dependent on temperature comprises a differential amplifier, a transistor in a feed back circuit of said differen-tial amplifier, a collector of said transistor being connected to the input side of said amplifier and an emitter of said transistor being connected to the output side of said amplifier.
3. A method of improving the temperature stability of a voltage source having a temperature-dependent actual-value voltage gauge, which comprises:
providing a reference-value voltage for said voltage source by means of a reference-value voltage circuit having an adjustable temperature coefficient;
and adjusting said adjustable temperature coefficient to produce a reference-value voltage which compensates for the temperature dependence of said actual-value voltage gauge, said reference value voltage being produced by summing the voltage outputs of a first voltage source independent of temperature and a second voltage source strongly dependent on temperature, and including regulating the output voltage of at least one of said first and second voltage sources before said summing to adjust the reference-value voltage.
providing a reference-value voltage for said voltage source by means of a reference-value voltage circuit having an adjustable temperature coefficient;
and adjusting said adjustable temperature coefficient to produce a reference-value voltage which compensates for the temperature dependence of said actual-value voltage gauge, said reference value voltage being produced by summing the voltage outputs of a first voltage source independent of temperature and a second voltage source strongly dependent on temperature, and including regulating the output voltage of at least one of said first and second voltage sources before said summing to adjust the reference-value voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA264,449A CA1085921A (en) | 1976-10-29 | 1976-10-29 | Method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA264,449A CA1085921A (en) | 1976-10-29 | 1976-10-29 | Method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085921A true CA1085921A (en) | 1980-09-16 |
Family
ID=4107148
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA264,449A Expired CA1085921A (en) | 1976-10-29 | 1976-10-29 | Method of improving the temperature stability of a voltage source, and a stabilized voltage source for carrying out the method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1085921A (en) |
-
1976
- 1976-10-29 CA CA264,449A patent/CA1085921A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |