Filter device for suppressing harmonics in radio frequency signals when dual frequencies exist

摘要

The present invention relates to a power amplifier device (10), switchable for at least two separate basic frequency bands, for radio frequency signals with effective suppression of harmonics, where harmonics, corresponding to a first basic frequency band, can be permitted to overlap the frequency range of at least one second basic frequency band. The power amplifier device (10) comprises a power amplifier (1) and an impedance matching circuit (2), switchable by means of a PIN-diode, which provides a load impedance adapted to each individual basic frequency band. Furthermore, the power amplifier device comprises a filter device (3) comprising a fixed low-pass filter (3b) and a switchable filter (3b) acting as an engageable and disengageable notch filter, which comprises at least one reversible PIN-diode. This switchable filter (3a) allows to pass, in a first mode, signals in the first basic frequency band and suppresses at the same time at least one order of harmonics corresponding to this basic frequency band. In a second mode, the second basic frequency band is transmitted without appreciable losses, and harmonics are suppressed by the fixed low-pass filter (3a).