Circuit for radiofrequency devices applicable to living tissues and device containing same
The supply circuit for the electrodes comprises a series resonant filter and a parallel resonant filter, tuned to admit the fundamental signal of the input signal and simultaneously and exponentially attenuate the remaining harmonics by increasing the frequency thereof, in such a way that the input signal with harmonics only passes the fundamental signal without attenuation to the output, while the harmonics causing interferences are increasingly attenuated as their frequency is raised.
1. A circuit for supplying output electrodes of a radiofrequency device applicable to living tissues, said circuit comprising:
a transformer having a primary winding, a secondary winding, and a turn ratio of 1:N, where N is a real number;
a resonant serial filter connected to the primary winding of the transformer having an inductor L S1 connected in series with a capacitor C S1 ; and
a resonant parallel filter connected to the secondary winding of the transformer having an inductor L p connected in parallel with a capacitor C P ;
wherein the resonant serial filter and the resonant parallel filter allow a fundamental signal of an input signal, which includes harmonics, to simultaneously pass through and exponentially attenuate the harmonics as a frequency of said harmonics increases, and
wherein an output frequency of said circuit is varied such that a combined impedance of a plurality of output electrodes connected to the circuit, and living tissue in contact with the output electrodes matches an impedance of the circuit.
2. The circuit of claim 1 , wherein the inductor L P of the resonant parallel filter is the parasitic inductance of the secondary winding of the transformer.
3. The circuit of claim 1 including anti-stimulus capacitors C S2 — CAP , C S2 — RES at each output electrode, each of said anti-stimulus capacitors C S2 — CAP , C S2 — RES having a corresponding inductor L S2-CAP , L S2-RES connected in series, the inductors L S2-CAP , L S2-RES having values that resonate at a fundamental frequency of the input signal.
4. The circuit of claim 1 , wherein the inductor L S1 and the capacitor C S1 of the resonant serial filter have a first impedance to the fundamental frequency of the input signal and a second impedance to the harmonics of the input signal, the first impedance being lower than the second impedance.
5. The circuit of claim 1 , wherein the inductor L P and the capacitor C p of the resonant parallel filter have a first impedance to the fundamental frequency of the input signal and a second impedance to the harmonics of the input signal, the first impedance being higher than the second impedance.
6. The circuit of claim 1 , wherein the radiofrequency device is a diathermy device.
7. The circuit of claim 1 , wherein the radiofrequency device is an electroscalpel device.