A power efficient, small-packaged radio frequency (RF) transmitter for use in avionics applications. The RF transmitter utilizes Cartesian feedback to operate a power amplifier with Class AB biasing and efficiency, while delivering Class A biasing performance. The RF transmitter includes interstage pads and high pass filters specially configured to meet demanding requirements for both adjacent channel power (ACP) limits and wideband spurious energy limits. The RF transmitter is much smaller in size and dissipates less DC power and heat than previous RF transmitters used in avionics applications.