EVEN HARMONIC DIRECT CONVERSION RECEIVER AND A TRANSCEIVER COMPRISING THE SAME

摘要

Conventionally, when a locally oscillated wave with about half the frequency of a received signal is inputted to a low-noise amplifier (2), a DC offset voltage due to the nonlinearity of the amplifier is produced, degrading the reception sensitivity. According to the invention, a filter means having a characteristic that suppresses a frequency band about half that of the received wave and passes the received wave, such as a band pass filter (12), a band block filter (13) or a high-pass filter (14), is provided before the low-noise amplifier (2) to prevent radiation waves with frequencies almost equal to that of the locally oscillated wave from being inputted into the low-noise amplifier (2). A filter circuit (15) is provided to the low-noise amplifier (2), so as to remove radiation waves that have entered the low-noise amplifier (2).