A Parallel Sliding-IF Receiver Front-End With Sub-2-dB Noise Figure for 5–6-GHz WLAN Carrier Aggregation

This article presents a parallel sliding-IF 5-6-GHz wireless local area network (WLAN) receiver front-end supporting two-band carrier aggregation (CA), which alleviates potential local oscillator (LO) pulling and crosstalk problems. The supported frequency spacing between any two different carriers ranges from tens to hundreds of MHz. First, a complementary current-reused single-ended LNA with very low noise figure (NF) is developed to guarantee a low noise performance. Second, an active balun-splitter establishes a bridge between the LNA and the following parallel fully differential down-conversion paths. Next, to optimize the performance of the passive double-conversion mixer, a detailed analysis has been conducted and shown that the time offset with specific values between the two LOs maximizes conversion gain and minimizes noise contribution, which enhances harmonic rejection simultaneously. Fabricated in 65-nm CMOS technology, this receiver front-end achieves an average 1.9-dB NF with a 39-dB gain at 5-6 GHz for single-carrier scenario, degraded by 0.4 dB with 35-dB gain for two-band CA scenario. It consumes 35 and 60 mA with 1.2-V supply for single carrier and two-band CA scenario, respectively. The total area is 0.56 mm
²
.