A low-IF direct sampling mixer with complex transfer function for ISDB-T one segment applications

A novel direct sampling mixer (DSM) with a complex transfer function has been developed for Integrated Service Digital Broadcasting-Terrestrial (ISDB-T) one segment applications. As its complex transfer function has an asymmetric frequency response with respect to clock frequency, an image rejection receiver can be realized with only one analog-to-digital converter (ADC) using the DSM. Furthermore, by using three-way, two-zero, three-pole IIR filters, a distinct deep notch shape is obtained at the image frequency. The proposed DSM was simulated using 65 nm CMOS technology, and an IRR of more than 25 dB was achieved. The architecture is appropriate for ISDB-T one-chip ICs.