In modern RF receiver circuit design, elimination of off-chip components is instrumental to the reduction of size, cost and power consumption. Many of these components are essential in current receiver designs in providing adequate filtering for channel selectivity and dynamic range. The zero-IF (direct-conversion) and low-IF receiver architectures become more attractive and can be alternatives to the design of heterodyne receiver. They offer the potential to greatly reduce the need for filters. However, a key component necessary for realizing both of these architectures is the precise extraction of the in-phase (I) and quadrature (Q) components of a signal: these components are vital in rejecting spurious (image) signals in a low-IF receiver, and are needed to recover a phase-modulated...[ Read more ]

In modern RF receiver circuit design, elimination of off-chip components is instrumental to the reduction of size, cost and power consumption. Many of these components are essential in current receiver designs in providing adequate filtering for channel selectivity and dynamic range. The zero-IF (direct-conversion) and low-IF receiver architectures become more attractive and can be alternatives to the design of heterodyne receiver. They offer the potential to greatly reduce the need for filters. However, a key component necessary for realizing both of these architectures is the precise extraction of the in-phase (I) and quadrature (Q) components of a signal: these components are vital in rejecting spurious (image) signals in a low-IF receiver, and are needed to recover a phase-modulated signal in the zero-IF receiver. Thus, the accuracy of quadrature separation thus directly affects the performance of the receiver.

In our research, an integrated circuit technique which subsamples the RF signal with accurate quadrature separation will be introduced. This technique can apply to any receiver architecture - heterodyne, low-IF and zero IF. It also yields the additional benefits of low-frequency, low-jitter LO generation for reduced power consumption, and greatly reduced LO interference when applied to zero-IF systems.