Galvanic isolation circuit, corresponding system and method

1. A system, comprising:

a differential transformer having a primary winding and a secondary winding configured to transmit signals over a carrier between the primary and secondary windings, wherein the primary and secondary windings have a galvanic isolation oxide layer therebetween, and wherein the primary and secondary windings each include a center tap providing low-impedance paths for dc and low frequency components of common-mode currents through the differential transformer; and

a pass-band circuit coupled to the secondary winding of the transformer, said pass-band circuit configured to permit propagation of signals over said carrier through the pass-band circuit while providing for a rejection of common-mode noise.

2. The system of claim 1 , further including a transmitter circuit coupled to the primary winding and a receiver coupled to the pass-band circuit.

3. The circuit of claim 1 , wherein said pass-band circuit includes a pass-band amplifier stage.

4. The circuit of claim 2 , wherein the pass-band amplifier stage is a differential amplifier stage.

5. The circuit of claim 1 , wherein said pass-band circuit includes a LC resonant load.

6. The circuit of claim 5 , wherein said LC resonant load includes at least one Q-factor adjusting resistance element.

7. The circuit of claim 1 , wherein said pass-band circuit is coupled to terminals of the secondary winding of the transformer.

8. A system, comprising:

a transmitter configured for transmitting signals over a carrier;

a receiver configured for receiving said signals over a carrier transmitted by said transmitter; and

a circuit positioned between said transmitter and said receiver, said circuit providing a galvanically isolated transmission path for said signals over the carrier between said transmitter and said receiver;

wherein said transmitter is coupled with the primary winding of said transformer; and

a pass-band circuit coupled with said receiver and configured to permit propagation of signals over said carrier through the pass-band circuit while providing for a rejection of common-mode noise.

9. The system of claim 8 , wherein said pass-band circuit includes a LC resonant load.

10. The system of claim 9 , wherein said LC resonant load includes at least one Q-factor adjusting resistance element.

11. The system of claim 8 , wherein said pass-band circuit is coupled to terminals of the secondary winding of the transformer.

12. The system of claim 8 , wherein said transmitter and said receiver include respective distinct grounds.

13. The system of claim 12 , wherein the primary winding has a center tap coupled to the distinct ground of the transmitter and wherein the secondary winding has a center tap coupled to the distinct ground of the receiver.

14. The system of claim 8 , further including an automatic gain control circuit active on said pass-band circuit to provide automatic gain control of said signals over the carrier.

15. A system, comprising:

a transmitter referenced to a first ground voltage and having an output;

a transformer having a primary winding and a secondary winding, wherein the primary winding is coupled to the output of the transmitter and has a center tap coupled to the first ground voltage;

a receiver referenced to a second ground voltage isolated from the first ground voltage and having an input coupled to the secondary winding, wherein the secondary winding has a center tap coupled to the second ground voltage; and

a differential amplifier circuit including a differential pair of input transistors coupled to terminals of the secondary winding and a differential pair of output terminals coupled to the input of the receiver;

wherein the differential amplifier circuit further includes an LC resonant load and at least one Q-factor adjusting resistance element.

16. The system of claim 15 , wherein the resistance element is coupled between the differential pair of output terminals.