Patent ID: 7868713
Filing Date: 2011-01-11
Classification: H04L

Abstract:
1. An impedance matching circuit comprising: a signal processing unit configured for identifying a frequency of a signal from an external transmission line and generating an identification signal according to the frequency; and a variable resistance unit configured for selecting a resistance matched with an actual impedance of the transmission line based on the identification signal; wherein the signal processing circuit comprises a micro controller unit, a data memory unit, and a firmware unit, the micro controller unit samples and counts the signal transmitted through the transmission line to identify the frequency of the signal, and generates the identification signal according to the frequency, the data memory unit receives and stores the identification signal, and the firmware generates a corresponding control signal according to the identification signal; wherein the variable resistance circuit comprises a selector and a plurality of resistors of various resistances, the resistors being connected between the selector and ground, the selector being connected to the transmission line and capable of electrically connecting the resistor with a matching resistance to the transmission line.