DC/AC bridge circuit
First Claim
1. A DC/AC converter bridge circuit comprising, an integrated circuit having connection terminals for the application of a high direct voltage and a low direct voltage, a first insulated gate field effect transistor whose drain is connected to a first connection terminal, a second insulated gate field effect transistor whose source is connected to a second connection terminal, the source of the first field effect transistor and the drain of the second field effect transistor both being connected to an output terminal, a control circuit for supplying an alternating control signal to a gate of the second field effect transistor and in inverted form to a gate of the first field effect transistor whereby the first and second field effect transistors can be made conducting and non-conducting in push-pull, said control circuit comprising an inverter stage having a third insulated gate field effect transistor whose source is connected to the second connection terminal, whose gate is connected to the gate of the second field effect transistor and whose drain is connected to a load element and to the gate of the first field effect transistor, characterized in that the current path of the inverter stage includes, in series with the load element and the third field effect transistor, a switch comprising a fourth transistor of a type complementary to the first, second and third field effect transistors and having a control electrode connected to a point of the circuit such that, during operation, a voltage is applied to the control electrode such that in the state in which the second and third field effect transistors are conducting the fourth field effect transistor is non-conducting or at least substantially non-conducting, and in that in the other state in which the second and third field effect transistors are non-conducting the fourth transistor is conducting.
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Accused Products
Abstract
In full or half DC/AC bridge circuits, the current through the control circuit, by which the power transistors T1,T2 are switched, is derived from the high supply voltage via a resistor. In order to reduce this current and the dissipation associated therewith, the control circuit includes an additional switch, preferably a MOST T4, which is non-conducting when the inverter transistor T3 is conducting and which is conducting when the transistor T3 is non-conducting. The control circuit thus becomes practically currentless. When the control electrode is applied to a suitable voltage, the transistor T4 can be controlled by its source voltage and thus becomes self-controlling. Thus, the circuit can be kept simple. The bridge circuit is particularly suitable for use with gas discharge lamps.
8 Citations
13 Claims
- 1. A DC/AC converter bridge circuit comprising, an integrated circuit having connection terminals for the application of a high direct voltage and a low direct voltage, a first insulated gate field effect transistor whose drain is connected to a first connection terminal, a second insulated gate field effect transistor whose source is connected to a second connection terminal, the source of the first field effect transistor and the drain of the second field effect transistor both being connected to an output terminal, a control circuit for supplying an alternating control signal to a gate of the second field effect transistor and in inverted form to a gate of the first field effect transistor whereby the first and second field effect transistors can be made conducting and non-conducting in push-pull, said control circuit comprising an inverter stage having a third insulated gate field effect transistor whose source is connected to the second connection terminal, whose gate is connected to the gate of the second field effect transistor and whose drain is connected to a load element and to the gate of the first field effect transistor, characterized in that the current path of the inverter stage includes, in series with the load element and the third field effect transistor, a switch comprising a fourth transistor of a type complementary to the first, second and third field effect transistors and having a control electrode connected to a point of the circuit such that, during operation, a voltage is applied to the control electrode such that in the state in which the second and third field effect transistors are conducting the fourth field effect transistor is non-conducting or at least substantially non-conducting, and in that in the other state in which the second and third field effect transistors are non-conducting the fourth transistor is conducting.
Specification
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- Resources
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Current AssigneeUS Philips Corporation (Koninklijke Philips N.V.)
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Original AssigneeUS Philips Corporation (Koninklijke Philips N.V.)
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InventorsSchoofs, Franciscus A. C. M., Ludikhuize, Adrianus W., van Mil, Job F. P.
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Primary Examiner(s)LaRoche, Eugene R.
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Assistant Examiner(s)Pascal, Robert J.
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Application NumberUS07/267,059Time in Patent Office494 DaysField of Search315/209 R, 315/224, 315/225, 315/240, 315/DIG. 5, 315/DIG. 7US Class Current315/209.00RCPC Class CodesH02M 7/538 in a push-pull configuratio...H03K 17/08122 in field-effect transistor ...H03K 19/01714 by bootstrapping, i.e. by p...H03K 2217/0036 Means reducing energy consu...H05B 41/2828 using control circuits for ...Y02B 20/00 Energy efficient lighting t...
