Device and method for power amplifier noise reduction
View Patent ↗A power amplifier for use in wireless communication devices is disclosed that reduces the noise generated at the output of the amplifier in the receive band of the wireless communication device. A resonant circuit is inserted between the base ballast resister and the lumped resister. The resonant frequency of the resonant circuit is adjusted to correspond to the frequency offset between the transmission frequency and the frequency corresponding to the peak noise in the receive band of the communication device.
1. A power amplifier, comprising:
a heterojunction bipolar transistor having a base node;
an RF input port electrically connected to the base node through a blocking capacitor;
a DC ballast resistor electrically connected between a common node and the base node;
a base biasing network connected to the common node; and
a resonant circuit connected to between the common node and a ground, the resonant circuit characterized by a resonant frequency in the range of 10 MHz to 100 MHz.
2. The power amplifier of claim 1 wherein the resonant frequency is in the range of 30 MHz to 80 MHz.
3. The power amplifier of claim 1 wherein the resonant circuit is an RLC circuit.
4. The power amplifier of claim 1 further comprising an AC ballast resistor connected between the base node and the blocking capacitor.
5. The power amplifier of claim 4 wherein the DC ballast resistor is electrically connected to the base node through the AC ballast resistor.