Patent ID: 8874061
Filing Date: 2014-10-28
Classification: H04B

Abstract:
1. A filtering apparatus for a dual-band sensing circuit, comprising: a dual-band sensing unit having a plurality of connecting terminals connected to a defined high-band sensing route, a defined low-band sensing route and a defined main-band sensing route, all of which are configured to receive signals from a sub-system of frequencies of different frequency ranges through a connect port, with the received signals categorized in accordance with the frequency ranges thereof; and at least one stepped impedance open stub is incorporated into the defined high-band sensing route for filtering out the signals of frequencies outside the first frequency range; a stepped impedance open stub in incorporated into the defined low-band sensing route for controlling two or more frequencies of transmission zeros to filter out the received signals suitable for being transmitted along the defined main-band sensing route and the defined high-band sensing route; one or more frequency detecting units coupled to the dual-band sensing unit for detecting the received signals that are transmitted along the defined high-band sensing route and the defined low-band sensing route, wherein the frequency detecting unit detects an energy of the received signals before converting the energy to corresponding voltages; one or more tunable gain amplifiers coupled to the frequency detecting units for receiving the voltages, and receiving an external controlling signal for tuning an amplifying gain of the tunable gain amplifier; one or more comparing units coupled to the tunable gain amplifiers, wherein the comparing unit introduces a reference voltage and processes a comparison operation between the reference voltage and the amplified voltage; and an RF switching unit coupled to the comparing unit and including a plurality of switches, wherein the RF switching unit receives a signal resulting from the comparison operation to turn on or turn off the switches and controls when to turn on a plurality of built-in notch filters including high-band notch filters and low-band notch filters; wherein the dual-band sensing categorizes the received signals within the different frequency ranges into the received signals within a first frequency range and the received signals within a second frequency range.