A wideband low-noise amplifier includes a source-degenerated common-source amplifier, a common-gate amplifier, and a matching frequency band determiner. The source-degenerated common-source amplifier is configured to amplify an input signal to output a first signal that is opposite in phase to the input signal. The common-gate amplifier is connected in parallel to the source-degenerated common-source amplifier to amplify the input signal to output a second signal that has the same phase as the input signal. The matching frequency band determiner is configured to isolate an input terminal of the source-degenerated common-source amplifier and an input terminal of the common-gate amplifier and determine a matching frequency band.