Broadband power amplifier systems and methods

A power amplifier module comprising:

• an input pin configured to receive a radio frequency input signal;
• an output pin configured to provide an amplified radio frequency signal;
• a power amplifier die including an amplifier circuit, an input pad electrically connected to the input pin, and an output pad electrically connected to the output pin, the power amplifier die further including a series inductor and a first capacitor configured in series with a first switch, a second capacitor configured in series with a second switch, and a third capacitor configured in series with a third switch;
• a switch die including the first, second, and third switches;
• and
• a plurality of interconnections configured to electrically connect the series inductor and the first capacitor with the first switch to provide a first harmonic trap, electrically connect the second capacitor to the second switch to provide a second harmonic trap, and to electrically connect the third capacitor to the third switch to provide a third harmonic trap, the first, second, and third switches configured to be in an ON position when the amplifier circuit operates in a low frequency band to reduce second-order harmonics in the amplified radio frequency signal.

A method to reduce harmonics in a radio frequency output signal, the method comprising:

• receiving along a radio frequency path at an input to a power amplifier circuit a radio frequency signal having a fundamental frequency in a band of operating frequencies;
• amplifying the radio frequency signal to provide an amplified radio frequency signal;
• matching an impedance of the power amplifier to an impedance of a next element in the radio frequency path;
• and
• filtering the amplified radio frequency signal with a harmonic rejection filter to reduce second-order harmonic frequencies when the power amplifier is operating in a low frequency band, the harmonic rejection filter including a switched harmonic trap, a first switched capacitor element, and a second switched capacitor element.