Tuning a programmable power line filter

1. A method of tuning a programmable power line filter, the power line filter comprising:

a live line, a neutral line, and a ground line connected to input terminals of the filter on an input side of the filter, the live line and the neutral line connected through inductors in the filter to output terminals on an output side of the filter;

at least one inductor disposed in the live line between the input terminals and the output terminals, this at least one inductor characterized by an input side and an output side; at least one inductor disposed in the neutral line between the input terminals and the output terminals, this at least one inductor also characterized by an input side and an output side;

a plurality of X-capacitors selectably connected through a first tuning switch between the live line and the neutral line on the input side of the inductors;

a plurality of X-capacitors selectably connected through a second tuning switch between the live line and the neutral line on the output side of the inductors; a plurality of Y-capacitors selectably connected through a third tuning switch between the live line and ground on the output side of the inductors; a plurality of Y-capacitors selectably connected through a fourth tuning switch between the neutral line and ground on the output side of the inductors; and

a tuning control circuit connected to the tuning switches and selectably connected through one or more programming switches to a load;

the method comprising:

measuring by the tuning control circuit an input impedance of the load; and

programming by the tuning control circuit the tuning switches in dependence upon the input impedance of the load.

2. The method of claim 1 further comprising configuring the tuning control circuit with load input impedance values associated with switch configurations for the tuning switches.

3. The method of claim 1 further comprising:

configuring the tuning control circuit with load input impedance values associated with switch configurations for the tuning switches;

wherein programming the tuning switches further comprises:

selecting a switch configuration in dependence upon the switch configuration's associated load input impedance value and the measured input impedance of the load; and

setting the tuning switches according to the selected switch configuration.

4. The method of claim 1 wherein measuring the input impedance of the load further comprises deriving, from sampled voltage values of a tuning pulse driven from the tuning control circuit through the load, the input impedance of the load.

5. The method of claim 1 wherein measuring the input impedance of the load further comprises:

driving by the tuning control circuit a tuning pulse through the load;

sampling by the tuning control circuit voltage values of the tuning pulse as output from the load; and

deriving by the tuning control circuit, in dependence upon the sampled voltage values the input impedance of the load.

6. The method of claim 1 wherein the tuning control circuit further comprises a tuning processor operably coupled through a data bus to a pulse generator and to a digital signal processor (‘DSP’), and measuring the input impedance of the load further comprises:

connecting, by the tuning processor, an output of the load to an input of the DSP;

driving a tuning pulse from the pulse generator through the load;

sampling the tuning pulse by the DSP as voltage values output from the load;

deriving by the DSP the input impedance of the load in dependence upon the sampled voltage values; and

providing the input impedance of the load by the DSP to the tuning processor.

7. The method of claim 1 wherein:

the tuning control circuit further comprises a tuning processor operably coupled through a data bus to non-volatile tuning memory;

the method further comprises storing, by the tuning processor in the non-volatile tuning memory, the measured input impedance of the load; and

programming the tuning switches further comprises programming the tuning switches by the tuning processor in dependence upon the stored input impedance of the load without remeasuring the input impedance of the load when power to the power line filter is cycled off and on.

8. A programmable power line filter comprising:

a live line, a neutral line, and a ground line connected to input terminals of the filter on an input side of the filter, the live line and the neutral line connected through inductors in the filter to output terminals on an output side of the filter;

at least one inductor disposed in the live line between the input terminals and the output terminals, this at least one inductor characterized by an input side and an output side; at least one inductor disposed in the neutral line between the input terminals and the output terminals, this at least one inductor also characterized by an input side and an output side; a plurality of X-capacitors selectably connected through a first tuning switch between the live line and the neutral line on the input side of the inductorsf; a plurality of X-capacitors selectably connected through a second tuning switch between the live line and the neutral line on the output side of the inductors; a plurality of Y-capacitors selectably connected through a third tuning switch between the live line and ground on the output side of the inductors; a plurality of Y-capacitors selectably connected through a fourth tuning switch between the neutral line and ground on the output side of the inductors; and

a tuning control circuit connected to the tuning switches and selectably connected through one or more programming switches to a load, the tuning control circuit configured to tune the filter by measuring an input impedance of the load and programming the tuning switches in dependence upon the input impedance of the load.

9. The filter of claim 8 further comprising the tuning control circuit configured with load input impedance values associated with switch configurations for the tuning switches.

10. The filter of claim 8 wherein the tuning control circuit is configured with load input impedance values associated with switch configurations for the tuning switches, and programming the tuning switches further comprises:

selecting a switch configuration in dependence upon the switch configuration's associated load input impedance value and the measured input impedance of the load; and

setting the tuning switches according to the selected switch configuration.

11. The filter of claim 8 wherein measuring the input impedance of the load further comprises deriving, from sampled voltage values of a tuning pulse driven from the tuning control circuit through the load, the input impedance of the load.

12. The filter of claim 8 wherein measuring the input impedance of the load further comprises:

driving by the tuning control circuit a tuning pulse through the load;

sampling by the tuning control circuit voltage values of the tuning pulse as output from the load; and

deriving by the tuning control circuit, in dependence upon the sampled voltage values the input impedance of the load.

13. The filter of claim 8 wherein the tuning control circuit further comprises a tuning processor operably coupled through a data bus to a pulse generator and to a digital signal processor (‘DSP’), and measuring the input impedance of the load further comprises:

connecting, by the tuning processor, an output of the load to an input of the DSP;

driving a tuning pulse from the pulse generator through the load;

sampling the tuning pulse by the DSP as voltage values output from the load;

deriving by the DSP the input impedance of the load in dependence upon the sampled voltage values; and

providing the input impedance of the load by the DSP to the tuning processor.

14. The filter of claim 8 wherein:

the tuning control circuit further comprises a tuning processor operably coupled through a data bus to non-volatile tuning memory;

the tuning control circuit is further configured to tune the filter by storing, by the tuning processor in the non-volatile tuning memory, the measured input impedance of the load; and

programming the tuning switches further comprises programming the tuning switches by the tuning processor in dependence upon the stored input impedance of the load without remeasuring the input impedance of the load when power to the power line filter is cycled off and on.

15. A computer program product for tuning a programmable power line filter, the power line filter comprising:

a live line, a neutral line, and a ground line connected to input terminals of the filter on an input side of the filter, the live line and the neutral line connected through inductors in the filter to output terminals on an output side of the filter;

at least one inductor disposed in the live line between the input terminals and the output terminals, this at least one inductor characterized by an input side and an output side; at least one inductor disposed in the neutral line between the input terminals and the output terminals, this at least one inductor also characterized by an input side and an output side; a plurality of X-capacitors selectably connected through a first tuning switch between the live line and the neutral line on the input side of the inductor; a plurality of X-capacitors selectably connected through a second tuning switch between the live line and the neutral line on the output side of the inductors; a plurality of Y-capacitors selectably connected through a third tuning switch between the live line and ground on the output side of the inductors; a plurality of Y-capacitors selectably connected through a fourth tuning switch between the neutral line and ground on the output side of the inductors; and

a tuning control circuit connected to the tuning switches and selectably connected through one or more programming switches to a load;

the computer program product disposed in a computer-readable recording medium, the computer program product comprising computer program instructions capable, when executed, of causing the tuning control circuit to tune the filter by measuring an input impedance of the load and programming the tuning switches in dependence upon the input impedance of the load.

16. The computer program product of claim 15 wherein the tuning control circuit is configured with load input impedance values associated with switch configurations for the tuning switches.

17. The computer program product of claim 15 wherein the tuning control circuit is configured with load input impedance values associated with switch configurations for the tuning switches and programming the tuning switches further comprises:

selecting a switch configuration in dependence upon the switch configuration's associated load input impedance value and the measured input impedance of the load; and

setting the tuning switches according to the selected switch configuration.

18. The computer program product of claim 15 wherein measuring the input impedance of the load further comprises:

driving by the tuning control circuit a tuning pulse through the load;

sampling by the tuning control circuit voltage values of the tuning pulse as output from the load; and

deriving by the tuning control circuit, in dependence upon the sampled voltage values the input impedance of the load.

19. The computer program product of claim 15 wherein the tuning control circuit further comprises a tuning processor operably coupled through a data bus to a pulse generator and to a digital signal processor (‘DSP’), and measuring the input impedance of the load further comprises:

connecting, by the tuning processor, an output of the load to an input of the DSP;

driving a tuning pulse from the pulse generator through the load;

sampling the tuning pulse by the DSP as voltage values output from the load;

deriving by the DSP the input impedance of the load in dependence upon the sampled voltage values; and

providing the input impedance of the load by the DSP to the tuning processor.

20. The computer program product of claim 15 wherein:

the tuning control circuit further comprises a tuning processor operably coupled through a data bus to non-volatile tuning memory;

the computer program product further comprises computer program instructions capable, when executed, of causing the tuning control circuit to tune the filter by storing, by the tuning processor in the non-volatile tuning memory, the measured input impedance of the load; and

programming the tuning switches further comprises programming the tuning switches by the tuning processor in dependence upon the stored input impedance of the load without remeasuring the input impedance of the load when power to the power line filter is cycled off and on.