Patent ID: 9326819
Filing Date: 2016-05-03
CPC Classification: A61B

Claim Text:
1. A microwave ablation system, comprising: a radio frequency (RF) antenna for positioning adjacent a biological tissue site; a transmission line having a first end connected to the RF antenna and a second end; an RF signal generator adapted to generate a train of RF pulses in the transmission line for transmission to the RF antenna; an impedance control circuit between the first end of the transmission line and the RF signal generator which is configured to modify the impedance of the RF signal generator part of the system based on a detected reflected power signal when the antenna is positioned adjacent the biological tissue site to be treated, the impedance control circuit comprising a printed circuit board; the impedance control circuit comprising a transformer which modifies the effective impedance of the power supply, a tuning stub which is selectively connected with the transformer in order to adjust the effective impedance of the impedance control circuit between two different impedances, a detector which monitors the reflected signal and a controller which receives the detector output and which is configured to control connection of the tuning stub to the transformer and disconnection of the tuning stub from the transformer based on the detected reflected power signal level, whereby the impedance control circuit has a first impedance when the tuning stub is not connected to the transformer and a second impedance higher than the first impedance when the tuning stub is connected to the transformer, the controller being configured to connect the tuning stub to the transformer when the reflected power signal is above a first predetermined value and to disconnect the tuning stub from the transformer when the reflected power signal is below a second predetermined value; and the impedance control circuit comprises a plurality of components and multiple layers of a monolithic substrate material, each layer carrying selected components of the impedance control circuit, and the tuning stub alone being integrated into one layer of the monolithic substrate material stacked between adjacent layers.