ADC for Passive Mixer First Radio Receiver Architectures

RF systems, such as radars and communication systems, increasingly use phased-array antenna systems to point the antenna beam anywhere in space. In a phased-array antenna system, the beamforming is controlled by setting the gain and phase of each RF channel. If phase and amplitude settings are independent, the beamforming is more easily implemented. AM-PM distortion affects this independency and is hence not desired. This thesis will look into a method to reduce AM-PM distortion in these RF channels. The gain and phase dependency will change if the load impedance is not constant. Mutual coupling between the antennas causes the load impedance to vary with the steering of the beam. This means that the AM-PM distortion becomes a function of mutual coupling. In this work, the focus is on the AM-PM distortion only, hence constant and real source and load impedances are used. The concept of a feedback system, with phase detection and phase correction, is presented. The implementation is based on QUBIC technology, which is a 0.25μm, BiCMOS process [1]. The operation is targeted at 3GHz.