Patent ID: 8644773

Claim:
A multiband low noise amplifier (LNA) for operation at multiple receive frequency bands in a portable communication device, the multiband LNA comprising: an amplifier element configured to receive a radio frequency (RF) signal at an RF input and provide an amplified version of the RF signal at an RF output; a resistive feedback circuit coupled between the RF input and the RF output; and a plurality of series-coupled resonant circuits coupled in series with the resistive feedback circuit between the RF input and the RF output of the amplifier element, each of the series-coupled resonant circuits having an inductance and a capacitance, each of the series-coupled resonant circuits being configured to resonate at a frequency that coincides with a desired receive frequency band, each of the series-coupled resonant circuits being configured to operate as an effective short circuit at a frequency other than a resonant frequency and being configured to operate as an effective open circuit at the resonant frequency to decouple the resistive feedback circuit from the amplifier element at each resonant frequency.