Circuit for generating triangular waveform having relatively short linear rise time and substantially long linear fall time

• US 7,834,592 B2
• Filed: 09/25/2008
• Issued: 11/16/2010
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: Pulsetech Products Corporation
• Original Assignee: Pulsetech Products Corporation
• Inventors: Sykes, David Lee, Smith, Pete Ward, Calcote, Clyde Ray, Huffman, James Earl
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): HERNANDEZ, MANUEL J
• Application Number:
  US12/238,271
• Publication Number:
  US 20090085526A1
• Time in Patent Office: 782 Days
• Field of Search: 320/139, 320/141, 320/145, 327/131, 327/132, 327/133, 327/134, 327/135, 327/136, 327/137, 327/138, 327/139, 327/140, 363/20, 363/21.01, 363/21.08, 363/21.1
• US Class Current: 320/141
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A circuit includes a pulse transformer having primary and secondary windings. An oscillating waveform is applied to the primary winding to induce an oscillating waveform at the secondary winding. A transistor in series with a first resistor is coupled between the secondary winding and the ground. An R-C network formed by a second and a third resistor and a capacitor is coupled to a base junction of the transistor. The R-C network causes a slow, tapered linear pinch off of the transistor'"'"'s conductance to enable the circuit to output a triangular waveform, which is characterized by a relatively short linear rise time followed by a substantially long linear fall time. The R-C network is coupled to the secondary winding via a first and a second diode, respectively.

Claims

1. A circuit, comprising:

a pulse transformer having primary and secondary windings, the primary winding having first and second terminals and a center terminal to which is coupled a DC source node, the secondary winding having third and fourth terminals;

a first transistor coupled between the second terminal of the primary winding and a ground node;

a first and a second resistor forming a voltage divider between the first terminal of the primary winding and the ground node, the voltage divider having a tap node coupled to a base junction of the first transistor;

a second transistor in series with a third resistor coupled between the third and fourth terminals of the secondary winding and the ground node; and

an R-C network formed by a fourth and a fifth resistor and a capacitor, the R-C network coupled to a base junction of the second transistor to cause a slow, tapered linear pinch off of the second transistor'"'"'s conductance to enable the circuit to output a triangular waveform, the R-C network coupled to the third and fourth terminals of the secondary winding via a first and a second diode, respectively.

2. The circuit according to claim 1, further comprising a third transistor coupled between the base junction of the first transistor and the ground node, the third transistor responsive to a pulse control signal to selectively turn ON and OFF the first transistor, wherein the pulse control signal is used to selectively prevent the generation of the triangular waveform.

3. The circuit according to claim 1, further comprising a third diode coupled between the second terminal of the primary winding and the ground node.

4. The circuit according to claim 1, further comprising a fifth resistor for coupling a second DC source to the base junction of the third transistor.

5. The circuit according to claim 1, further comprising a fourth diode coupling an external battery to the third terminal of the secondary winding.

6. The circuit according to claim 1, wherein the triangular waveform is characterized by a relatively short linear rise time followed by a substantially long linear fall time.

7. The circuit according to claim 1, wherein the triangular waveform has a linear rise time of approximately 412 million V/sec.

8. The circuit according to claim 1, wherein the triangular waveform has a linear fall time of approximately 40 million V/sec.

9. The circuit according to claim 1, wherein the triangular waveform has a frequency between 30 KHz and 50 KHz.

10. The circuit according to claim 1, wherein the fourth and the fifth resistors are connected in series, and wherein the capacitor is connected in parallel to the fifth resistor forming a common node of the R-C network to which is coupled the base junction of the second transistor.

11. The circuit according to claim 1, further comprising a third diode coupling an external battery to the secondary winding, the external battery being charged by the application of the triangular waveform.

12. The circuit according to claim 1, wherein the triangular waveform is applied to a battery being charged.

13. The circuit according to claim 1, wherein the triangular waveform is superimposed on a DC bias signal and the resulting waveform is applied to a battery.

14. The circuit according to claim 13, wherein the triangular waveform has a linear rise time of approximately 412 million V/sec.

15. The circuit according to claim 13, wherein the triangular waveform has a linear fall time of approximately 40 million V/sec.

16. The circuit according to claim 13, wherein the triangular waveform has a frequency between 30 KHz and 50 KHz.