RF-coupled digital isolator

1. An RF-coupled digital isolator, comprising:

a first leadframe portion including a first finger;

a second leadframe portion including a second finger;

wherein the first finger and the second finger are electrically isolated from one another; and

wherein the first finger acts as a primary of a transformer, and the second finger acts as a secondary of the transformer, when an RF signal drives the first finger.

2. The RF-coupled digital isolator of claim 1 , wherein the second finger acts as the primary of the transformer, and the first finger acts as the secondary of the transformer, when a further RF signal drives the second finger.

3. The RF-coupled digital isolator of claim 1 , wherein:

the first leadframe portion is connected to a first ground; and

the second leadframe portion is connected to a second ground that is electrically isolated from the first ground.

4. The RF-coupled digital isolator of claim 1 , further comprising:

an oscillator that generates the RF signal; and

a first bondwire that connects an output of the oscillator to an extremity of the first finger; and

a second bondwire that connects an extremity of the second finger to an input of an amplifier;

wherein the amplifier amplifies a signal generated by the second finger, when the RF signal generated by the oscillator drives the first finger.

5. The RF-coupled digital isolator of 1 , wherein the first finger and the second finger are electrically isolated from one another by a molding compound that forms a package for the digital isolator.

6. The RF-coupled digital isolator of claim 1 , wherein the first finger and the second finger are substantially parallel to one another.

7. The RF-coupled digital isolator of claim 1 , wherein the first finger and the second finger are substantially anti-parallel to one another.

8. The RF-coupled digital isolator of claim 1 , wherein:

the first leadframe portion also includes a third finger;

the second leadframe portion also includes a fourth finger;

the third finger and the fourth finger are electrically isolated from one another; and

the fourth finger acts as a primary of a second transformer, and the third finger acts as a secondary of the second transformer, when a further RF signal drives the fourth finger.

9. The RF-coupled digital isolator of claim 8 , wherein:

the first finger and the second finger are substantially parallel to one another; and

the third finger and the fourth finger are substantially parallel to one another.

10. The RF-coupled digital isolator of claim 8 , wherein:

the first finger and the second finger are substantially anti-parallel to one another; and

the third finger and the fourth finger are substantially anti-parallel to one another.

11. An RF-coupled digital isolator, comprising:

the first leadframe portion including a first finger; and

the second leadframe portion including a second finger, which is electrically isolated from the first finger;

wherein the first and second fingers are configured as a finger transformer; and

wherein a mutual inductance between the first and second fingers enables a change in voltage and/or current in one of the first and second fingers to be detected by the other one of the first and second fingers.

12. The RF-coupled digital isolator of claim 11 , wherein:

the first leadframe portion also includes a third finger; and

the second leadframe portion also includes a fourth finger;

the third finger and the fourth finger are electrically isolated from one another; and

a mutual inductance between the third and fourth fingers enables a change in voltage and/or current in one of the third and fourth fingers to be detected by the other one of the third and fourth fingers.

13. The RF-coupled digital isolator of claim 12 , wherein:

the first finger and the second finger are substantially parallel to one another; and

the third finger and the fourth finger are substantially parallel to one another.

14. The RF-coupled digital isolator of claim 12 , wherein:

the first finger and the second finger are substantially anti-parallel to one another; and

the third finger and the fourth finger are substantially anti-parallel to one another.

15. An RF coupled digital isolator, comprising:

a first finger;

a second finger, which is electrically isolated from the first finger;

wherein the first and second fingers are configured as a finger transformer;

wherein the first finger is part of a first portion of a split leadframe;

wherein the second finger is part of a second portion of the split leadframe; and

wherein the second portion of the split leadframe is electrically isolated from the first portion of the split leadframe; and

wherein a mutual inductance between the first and second fingers enables a signal to be detected at the second finger of the finger transformer, when the first finger is driven with an RF signal.

16. The digital isolator of claim 15 , wherein the mutual inductance between the first and second fingers enables a signal to be detected at the first finger of the finger transformer, when the second finger is driven with a further RF signal.

17. A method for providing digital isolation, comprising:

driving a first finger of a finger transformer with an RF signal, wherein the finger transformer includes the first finger and a second finger electrically isolated from the first finger, with a mutual inductance between the first and second fingers, the first finger being part of a first portion of a split leadframe, and the second finger being part of a second portion of the split leadframe; and

detecting a signal at the second finger of the finger transformer, as a result of the first finger being driven with the RF signal and the mutual inductance between the first and second fingers.

18. The method of claim 17 , further comprising, at a time when the first finger is not being driven with the RF signal;

driving the second finger of the finger transformer with a further RF signal; and

detecting a signal at the first finger of the finger transformer, as a result of the second finger being driven with the further RF signal and the mutual inductance between the first and second fingers.

19. The method of claim 17 , further comprising:

amplifying the signal detected at the second finger to produce an amplified version of the signal detected at the second finger; and

demodulating the amplified version of the signal detected at the second finger.

20. The method of claim 17 , further comprising providing the finger transformer.