A reconfigurable baseband circuit applied for WiMAX low-IF receivers

This paper presents a reconfigurable baseband circuit for WiMAX low-IF receivers, including a complex filter and 2 automatic gain controllers (AGCs) for I and Q channels. Only by changing the capacitor values can the center and cutoff frequencies of the complex filter be adjusted simultaneously to realize the reconfigurability. Meanwhile, a novel one-step method to obtain fast gain settling of AGCs is proposed. The chip is fabricated in 0.13- µm CMOS technology, occupies 0.9 × 1.3 mm², and consumes 14.8 mW of power with a 1.2-V power supply. The measurement results show a reconfigurable bandwidth of 2K to 3.5/5/10 MHz, a gain range of 10 to 58 dB, and a total harmonic distortion of 0.43%to 1.66%.