Communication over power lines

1. A method comprising:

generating a first PWM waveform signal, wherein a duty cycle of the first PWM waveform signal is proportional to an amplitude of a first signal;

generating a first sinusoidal waveform signal having a first frequency;

modulating the first sinusoidal waveform signal in relation to the first PWM waveform signal;

transmitting the modulated first sinusoidal waveform signal to a circuit via a power conductor that couples a power source to the circuit;

the circuit generating a demodulated signal by demodulating the modulated first sinusoidal waveform signal;

generating a second PWM waveform signal, wherein a duty cycle of the second PWM waveform signal is proportional to an amplitude of a second signal;

generating a second sinusoidal waveform signal at a second frequency;

modulating the second sinusoidal waveform signal in relation to the second PWM waveform signal;

transmitting the modulated second sinusoidal waveform signal to the circuit and to a second circuit via the power conductor that couples the power source to the second circuit;

the second circuit generating a second demodulated signal by demodulating the modulated second sinusoidal waveform signal.

2. The method of claim 1 further comprising the circuit generating an integrated signal by integrating the demodulated signal during an integration cycle period.

3. The method of claim 2 further comprising:

the circuit generating an amplified signal by amplifying the integrated signal;

transmitting the amplified signal to an input of a power driver that is coupled to the power conductor.

4. The method of claim 3 wherein an output of the power driver is coupled to a power input of a load.

5. The method of claim 1 further comprising an act of transmitting the demodulated signal to a switch that is coupled to the power conductor.

6. The method of claim 1 further comprising an act of transmitting the demodulated signal to a gate of a FET that is coupled to the power conductor.

7. The method of claim 6 wherein the FET is coupled between the power conductor and a power input of a device.

8. The method of claim 1 :

wherein the first frequency is distinct from the second frequency;

wherein the power conductor concurrently transmits the modulated first and second sinusoidal waveform signals.

9. An apparatus comprising:

a first PWM circuit for generating a first PWM waveform signal, wherein a duty cycle of the first PWM waveform signal is proportional to an amplitude of a first signal;

a first circuit for generating a first sinusoidal waveform signal having a first frequency;

a first modulator circuit for modulating the first sinusoidal waveform signal in relation to the first PWM waveform signal;

a power source;

a conductor coupled to an output of the power source and an output of the first modulator circuit;

a second PWM circuit for generating a second PWM waveform signal, wherein a duty cycle of the second PWM waveform signal is proportional to an amplitude of a second signal;

a second circuit for generating a second sinusoidal waveform signal having a second frequency that is distinct from the first frequency;

a second modulator circuit for modulating the second sinusoidal waveform signal in relation to the second PWM waveform signal;

wherein the conductor is coupled to an output of the second modulator circuit.

10. The apparatus of claim 9 further comprising

a first demodulator circuit coupled to receive the modulated first sinusoidal waveform signal from the first modulator circuit via the conductor;

wherein the first demodulator circuit is configured to generate a first demodulated signal by demodulating the modulated first sinusoidal waveform signal.

11. The apparatus of claim 10 further comprising:

a first power driver circuit coupled to a power input of a first load and the power source, wherein the first power driver circuit is coupled to the power source via the conductor;

wherein a control signal input of the first power driver circuit is coupled to receive the first demodulated signal.

12. The apparatus of claim 10 further comprising:

a first power driver circuit coupled to a power input of a first load and the power source, wherein the first power driver circuit is coupled to the power source via the conductor;

a first circuit coupled to receive the first demodulated signal and configured to generate a first control signal that is proportional to the first signal.

13. The apparatus of claim 12 wherein a control signal input of the first power driver circuit is coupled to receive the first control signal.

14. The apparatus of claim 12 further comprising:

an amplifier circuit configured to receive and amplify the first control signal;

wherein a control signal input of the first power driver circuit is coupled to receive the amplified first control signal.

15. An apparatus comprising:

a power source;

a conductor coupled to the power source and configured to transmit electrical power;

a first demodulator circuit coupled to the conductor and configured to receive a first modulated signal via the conductor;

wherein the first demodulator circuit is configured to generate a first PWM signal in response to demodulating the first modulated signal;

a second demodulator circuit coupled to the conductor and configured to receive a second modulated signal via the conductor;

wherein the second demodulator circuit is configured to generate a second PWM signal in response to demodulating the second modulated signal;

wherein the second demodulator circuit is configured to receive the second modulated signal while the first demodulator receives the first modulated signal.

16. The apparatus of claim 15 further comprising a switch coupled between the conductor and a load, wherein the switch comprises a control input coupled to receive the first PWM signal.

17. The apparatus of claim 15 further comprising:

a circuit for generating an analog control signal, wherein a voltage amplitude of the analog control signal is proportional to a duty cycle of the first PWM signal;

a power driver coupled to the conductor and a load, wherein the power driver comprises a an input configured to receive the analog control signal.