Granted Patent B2

US 6,838,862 · App. 10/407,689 · Granted Jan 4, 2005

Abstract

Claims (30)

1. A pulse width modulation apparatus, comprising:

a load circuit, including a load;

a signal switch that isolates the load circuit from a voltage source along a signal path;

a shunt switch, connected to the signal path at a point between the signal switch and the load circuit, that isolates the signal path from a ground voltage;

a resistor connected in series between the signal switch and the shunt switch.

2. An apparatus as set forth in claim 1 , wherein the apparatus further includes a shunt diode, connected to the signal path at its cathode and to a ground voltage at its anode.

3. An apparatus as set forth in claim 1 , wherein the load comprises an antenna.

4. An apparatus as set forth in claim 1 , wherein the load circuit further comprises a filter.

5. An apparatus as set forth in claim 4 , wherein the filter comprises at least one inductor.

6. An apparatus as set forth in claim 1 , wherein the signal switch and the shunt switch comprise transistors.

7. An apparatus as set forth in claim 1 , wherein the apparatus further comprises a pulse generator that receives an input signal and generates a corresponding pulse width modulated drive signal.

8. An apparatus as set forth in claim 1 , wherein the apparatus is implemented within a broadcast transmission system.

9. A pulse width modulation system, comprising:

a power supply that provides voltage to a load circuit along a signal path;

a signal switch that controls the flow of current along the signal path;

a shunt switch that controls the flow of current from the signal path to a ground voltage; and

a resistor that restricts the flow of current between the signal switch and the shunt switch.

10. A system as set forth in claim 9 , wherein the system further includes a pulse generator that receives an input signal and generates a corresponding pulse width modulated drive signal.

11. A system as set forth in claim 10 , wherein the signal switch is controlled by the drive signal.

12. A system as set forth in claim 10 , wherein the shunt switch is controlled by an inversion of the drive signal.

13. A system as set forth in claim 9 , wherein the system further includes a shunt diode that selectively prevents the flow of current from the signal path to a ground voltage.

14. A system as set forth in claim 13 , wherein the shunt diode is connected to the signal path at its cathode, such that it prevents the flow of current until a threshold voltage is exhibited at a point of connection.

15. A system as set forth in claim 9 , wherein the load circuit comprises a filter and a load, the filter correcting a plurality of signal pulses provided to the load, each signal pulse having an associated pulse width.

16. A system as set forth in claim 15 , wherein the filter stores residual energy when a signal pulse is received at the circuit and discharges the residual energy between signal pulses.

17. A system as set forth in claim 16 , wherein the residual energy is shunted as a current through the shunt diode for signal pulses above a threshold width, and the residual energy is shunted as a current through the shunt switch when the pulse width associated with the signal pulse is below a threshold width.

18. A system as set forth in claim 9 , wherein the system is implemented within a broadcast transmission system.

19. A method of generating a pulse width modulated signal, comprising:

providing signal pulses, having an associated pulse width, across a load circuit, such that the load circuit accumulates residual energy;

shunting the residual energy from each signal pulse through a shunt diode when the associated pulse width of the signal pulse is above a threshold width;

shunting the residual energy from each signal pulse through a shunt switch when the associated pulse width of the signal is below a threshold width.

Assignments (15)