Regulating temperature-compensated output voltage
View Patent ↗A low-voltage bandgap reference circuit includes a current source supplying a reference voltage rail. The circuit further includes a V be loop branch coupled to the reference voltage rail to obtain a V be voltage with a negative temperature coefficient. The circuit further includes a ΔV be loop branch to obtain a ΔV be voltage, the ΔV be loop branch employing a fractional V be voltage, to provide a reduced, positive temperature coefficient. The circuit further includes a feedback amplifier that sets identical voltages from the loop branches on inputs of the amplifier A to regulate an output voltage of the circuit on the reference voltage rail at a temperature-compensated value below 1.2V.
1. A low-voltage bandgap reference circuit comprising:
a current source supplying a reference voltage rail;
a V be loop branch coupled to the reference voltage rail to obtain a V be voltage with a negative temperature coefficient;
a ΔV be loop branch to obtain a ΔV be voltage, the ΔV be loop branch employing a fractional V be voltage, to provide a reduced, positive temperature coefficient;
a feedback amplifier that sets identical voltages from the loop branches on inputs of the amplifier to regulate an output voltage of the circuit on the reference voltage rail at a temperature-compensated value below 1.2V.
2. The circuit of claim 1 , wherein the output voltage is regulated on the reference voltage rail at the temperature-compensated value below 1.2V without trimming.
3. The circuit of claim 1 , wherein the output voltage is regulated on the reference voltage rail at the temperature-compensated value below 1.2V with an accuracy better than ±1%.
4. The circuit of claim 1 , wherein the ΔV be voltage is a difference in base-emitter voltages of two transistors reduced by the fractional V be voltage.
5. The circuit of claim 1 , wherein the fractional V be voltage is created on a resistor, and the value of the fractional V be voltage is given by a ratio of the resistor and another resistor.
6. The circuit of claim 1 , wherein the output voltage may be set by balancing four resistors.
7. The circuit of claim 1 , wherein the output voltage is given by
2
(
R
2
R
1
)
V
T
ln
N
+
V
be
1
-
2
(
V
be
2
)
(
R
4
R
3
)
(
R
2
R
1
)
.
8. The circuit of claim 1 , wherein an input voltage of the circuit is higher than the output voltage by less than 10 millivolts.
9. An integrated circuit device comprising:
a package;
pins coupled to the package; and
a low-voltage bandgap reference circuit, housed by the package, comprising:
a V be loop branch coupled to a reference voltage rail to obtain a V be voltage with a negative temperature coefficient;
a ΔV be loop branch to obtain a ΔV be voltage, the ΔV be loop branch employing a fractional V be voltage, to provide a reduced, positive temperature coefficient;
a feedback amplifier that sets identical voltages from the loop branches on inputs of the amplifier to regulate an output voltage of the circuit on the reference voltage rail at a temperature-compensated value below 1.2V.
10. The device of claim 9 , wherein the output voltage is regulated on the reference voltage rail at the temperature-compensated value below 1.2V without trimming.
11. The device of claim 9 , wherein the output voltage is regulated on the reference voltage rail at the temperature-compensated value below 1.2V with an accuracy better than ±1%.
12. The device of claim 9 , wherein the ΔV be voltage is a difference in base-emitter voltages of two transistors reduced by the fractional V be voltage.
13. The device of claim 9 , wherein the fractional V be voltage is created on a resistor, and the value of the fractional V be voltage is given by a ratio of the resistor and another resistor.
14. The device of claim 9 , wherein the output voltage may be set by balancing four resistors.
15. The device of claim 9 , wherein the output voltage is given by
2
(
R
2
R
1
)
V
T
ln
N
+
V
be
1
-
2
(
V
be
2
)
(
R
4
R
3
)
(
R
2
R
1
)
.
16. The device of claim 9 , wherein an input voltage of the circuit is higher than the output voltage by less than 10 millivolts.
17. A semiconductor apparatus comprising:
a semiconductor wafer; and
circuits formed in or on the wafer, each circuit comprising:
a V be loop branch coupled to a reference voltage rail to obtain a V be voltage with a negative temperature coefficient;
a ΔV be loop branch to obtain a ΔV be voltage, the ΔV be loop branch employing a fractional V be voltage, to provide a reduced, positive temperature coefficient;
a feedback amplifier that sets identical voltages from the loop branches on inputs of the amplifier to regulate an output voltage of the circuit on the reference voltage rail at a temperature-compensated value below 1.2V.
18. The apparatus of claim 17 , wherein the output voltage is regulated on the reference voltage rail at the temperature-compensated value below 1.2V with an accuracy better than ±1% without trimming.
19. The apparatus of claim 17 , wherein the output voltage is regulated on the reference voltage rail at the temperature-compensated value below 1.2V with an accuracy better than ±1%.
20. The apparatus of claim 17 , wherein the ΔV be voltage is a difference in base-emitter voltages of two transistors reduced by the fractional V be voltage.