US 10,376,301 B2
Logarithmic amplifier, electrosurgical generator including same, and method of controlling electrosurgical generator using same
Donald W. Heckel, Thornton, CO (US); and Robert J. Behnke, II, Erie, CO (US)
Assigned to COVIDIEN LP, Mansfield, MA (US)
Filed by Donald W. Heckel, Thornton, CO (US); and Robert J. Behnke, II, Erie, CO (US)
Filed on Sep. 28, 2011, as Appl. No. 13/247,043.
Prior Publication US 2013/0079763 A1, Mar. 28, 2013
Int. Cl. H03G 3/10 (2006.01); A61B 18/12 (2006.01); A61B 18/18 (2006.01); H03G 3/20 (2006.01); A61B 18/00 (2006.01)
CPC A61B 18/1206 (2013.01) [A61B 2018/00642 (2013.01); A61B 2018/00779 (2013.01); A61B 2018/00827 (2013.01); A61B 2018/00875 (2013.01); A61B 2018/00892 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A control system for controlling an electrosurgical generator, comprising:
a voltage sensor configured to sense a voltage signal of electromagnetic energy generated by the electrosurgical generator via a transmission line and to generate a voltage sensor signal, wherein the voltage sensor is a dual directional coupler including:
a first line coupler including a first line portion distanced with a third line portion of the transmission line and configured to measure a forward voltage signal, the first line portion being coupled between a first node and a system ground; and
a second line coupler including a second line portion, which is separate from the first line portion, distanced with the third line portion of the transmission line and configured to measure a reflected voltage signal, the second line portion being coupled between the system ground and a second node different from the first node;
a current sensor configured to sense a current signal of the electromagnetic energy generated by the electrosurgical generator and to generate a current sensor signal;
a first log amplifier coupled to the voltage sensor and configured to amplify and compress the voltage sensor signal to obtain a voltage log signal;
a second log amplifier coupled to the current sensor and configured to amplify and compress the current sensor signal to obtain a current log signal; and
a controller configured to generate an output log impedance signal by subtracting the current log signal from the voltage log signal, and to control the electrosurgical generator based on the output log impedance signal.