Time-Interleaved Phased Arrays With Parallel Signal Processing in RF Modulations

The proposed time-interleaved phased array is a functional integration of a space-time domain filter in antenna arrays and a time-frequency domain filter in mixer arrays. Spatially sampled signals by the antenna arrays will be interleaved in time by the mixer arrays to increase modulation speed while leveraging relatively low-frequency carriers. In M-element time-interleaved arrays, the carriers frequency can be reduced by the factor of M to realize an equivalent functionality as in conventional phased arrays based on fundamental carrier modulations. Depending on the array configuration, the time-interleaved phased array can be categorized as “correlated-noise time-interleaved (CNTI)” array or “uncorrelated-noise time-interleaved (UNTI)” array. In the CNTI-array, both signal and correlated noise will be interleaved resulting in the same filter response for the signal and noise, whereas in the UNTI-array only signal will be interleaved in time domain: uncorrelated noise will not participate in the time-interleaving process. An extensive noise analysis for both array types is provided in the paper. To achieve maximum SNR, noise filtering techniques are proposed and verified through CAD behavioral simulations. In essence, the time-interleaved array architecture is a mix of parallel signal processing at RF and LO domains, which can have an advantage in compensating system performance deficits due to an active device speed limitation at high frequencies at the expense of an endurable system complexity.

I. Introduction

Time interleaving technique has been widely used in analog electronics to achieve high speed signal processing [1]. In essence, the technique is a parallel array signal process where individual array elements operate with a suboptimal speed and outputs from the array elements are interleaved parallel in time. In such ways, effectively overall signal processing speed can be increased by the factor of time interleaving factor. In fact, the parallelism in signal processing has been a successful tradeoff of a system complexity for a high sampling speed under a limitation of transistor speed in data converter designs [2]. This paper proposes the time-interleaved parallel signal processing in phased arrays to enable integrated phased array transceivers toward sub-terahertz regimes under a constraint of active device speed limitation.