Cartesian Feedback Loop Transmitter
The AK2403 is a transmitter IC with the Cartesian Feedback Loop Linearization Technique. The AK2403 realize high linearity by receiving feedback signal from an external Power Amplifier (PA) via a coupler. The core circuit of Cartesian Feedback Loop consists of forward path part and feedback path part.
The forward path consists of differential amplifier and I/Q modulator. And the feedback path consists of attenuator, demodulator, phase shifter and differential to single amplifier. Since the AK2403 has a built- in DAC and PLL, the area of the system can be reduced. The built-in PLL in the AK2403 can generate Local signal by using built-in VCO or external VCO. The AK2403 can execute the DC offset calibration automatically by using the built-in DAC.