Diode substitute with low drop and minimal loading
View Patent ↗A voltage rectifier circuit having a storage element and a switching stage that is switchable to enable the storage element to capture a peak voltage of an alternating power source. The switching stage includes transistors arranged in a back-to-back configuration. In one example, the storage element is a capacitor and the transistors are PNP bipolar junction transistors. The configuration of the circuit enables reduced loading on the power source, as well as reduced sensitivity to temperature.
1. A voltage rectifier circuit comprising:
a storage element; and
a switching stage that is switchable to enable the storage element to capture a peak voltage of an alternating power source,
wherein the switching stage includes a plurality of PNP transistors,
wherein emitters of a first one and a second one of the PNP transistors are directly connected to each other and are further connected to a voltage source distinct from the alternating power source.
2. The voltage rectifier circuit according to claim 1 , wherein a base of the first one of the PNP transistors is connected with the alternating power source.
3. The voltage rectifier circuit according to claim 1 , further comprising a resistor connected in parallel with the storage element.
4. The voltage rectifier circuit according to claim 3 , wherein a base and a collector of one of the PNP transistors are connected with the storage element and the resistor.
5. The voltage rectifier circuit according to claim 1 , wherein an output current of one the PNP transistors is set to be a peak current of the alternating power source.
6. The voltage rectifier circuit according to claim 1 , wherein the PNP transistors are substantially identical.
7. The voltage rectifier circuit according to claim 1 , wherein the plurality of PNP transistors include at least four PNP transistors.
8. The voltage rectifier circuit according to claim 7 , wherein a base of a third one of the PNP transistors is connected with the alternating power source.
9. The voltage rectifier circuit according to claim 7 , wherein an output current of one of the PNP transistors is set to be a peak current of the alternating power source.
10. The voltage rectifier circuit accordingly to claim 7 , wherein, among four of the PNP transistors, PNP transistors of a first pair of the four PNP transistors are substantially identical with one another, and PNP transistors of a second pair of the four PNP transistors are substantially identical with one another.
11. The voltage rectifier circuit according to claim 1 , wherein at least one of temperature coefficients and voltage drops across the PNP transistors essentially cancel out.
12. The voltage rectifier circuit according to claim 1 , wherein the storage element is a capacitor.
13. The voltage rectifier circuit accordingly to claim 1 , wherein a base of one of the two PNP transistors is connected with an emitter of a further one of the PNP transistors.
14. The voltage rectifier circuit accordingly to claim 1 , wherein the circuit provides minimal loading on the alternating power source.
15. The voltage rectifier circuit according to claim 1 , wherein the switching stage includes PNP transistors arranged in a back-to-back configuration.
16. A voltage rectifier circuit comprising:
a storage element; and
a switching stage that is switchable to enable the storage element to capture a peak voltage of an alternating power source,
wherein the switching stage includes a plurality of PNP transistors, and
wherein a base and a collector of a first one of the PNP transistors are directly connected together.
17. The voltage rectifier circuit according to claim 16 , wherein a base of a second one of the PNP transistors is connected with the alternating power source.
18. The voltage rectifier circuit according to claim 16 , wherein emitters of at least two of the PNP transistors are directly connected together.
19. The voltage rectifier circuit according to claim 16 , further comprising a resistor connected in parallel with the storage element.
20. The voltage rectifier circuit according to claim 19 , wherein a base and a collector of one of the PNP transistors are connected with the storage element and the resistor.
21. The voltage rectifier circuit according to claim 16 , wherein an output current of one the PNP transistors is set to be a peak current of the alternating power source.
22. A voltage rectifier circuit comprising:
a storage element; and
a switching stage that is switchable to enable the storage element to capture a peak voltage of an alternating power source,
wherein an output current of one of the transistors is set to be a peak current of the alternating power source and,
wherein an output current of at least another of the transistors is set to be between 10% and 20% of the output current of the one of the transistors.
23. A voltage rectifier circuit comprising:
a storage element; and
a switching stage that is switchable to enable the storage element to capture a peak voltage of an alternating power source,
wherein the switching stage includes bipolar junction transistors,
wherein a base of a first one of the bipolar junction transistors is connected with the alternating power source, and
wherein a base and a collector of a second of the bipolar junction transistors are directly connected together, such that the second of the bipolar junction transistors behaves as a diode with a forward voltage of about 0.7 volts.