A SFA and I/Q mismatch auto-calibration scheme for high IRR multi-mode GPS RF receiver

A signal frequency adaptable (SFA) and I /Q mismatch auto-calibration scheme for multi-mode GPS RF receiver is proposed in this paper. The novelty of this calibration scheme is two-folded. One is the calibration structure, which includes not only the analog PGA, the comparator, the error detector, and the 5th complex filter, but also the clock synthesizer and the dual channel MUX for signal frequency adaptability. The other is the algorithm, which is based on binary tree adaptive feedback concept and combined with sign-sign error update method, so only four sign symbols are tested. Simulations show the proposed auto-calibrating scheme achieves 59dB and 48 dB IRR through manual and automatic calibration, respectively. The calibration circuit is fabricated in 0.18 μm RF CMOS technology and consumes 8mA with 1.9 V power supply.