Design and Analysis of a Blocker-Tolerant Gain-Boosted N-Path Receiver Using a Bottom-Plate Switched-Capacitor Technique

Abstract

This paper reports a wideband blocker-tolerant receiver (RX) that covers a 0.5-to-2 GHz radio frequency (RF) range. By combining the gain-boosted (GB) mixer-first low-noise amplifier (LNA) network with a bottom-plate switched-capacitor (SC) N-path filter, the proposed RX provides a high RF gain and high out-of-band (OOB) blocker suppression to improve both the noise figure (NF) and OOB linearity. Particularly, our RX features enhanced filtering at the input side that can effectively prevent the OOB blockers from entering into the RX. By deriving its linear time-invariant (LTI) model, the input impedance matching, gain response and noise performance are analyzed. Besides that, a clock-delay technique is proposed to improve the LO non-overlap characteristics. Designed in 65-nm CMOS, the simulated results present that under an 80-MHz offset frequency, the RX scores a 29 dBm OOB-IIP3 and a -2.3 dBm B-1dB. The NF ranges between 3.2 to 6 dB, and the active area is 0.66 mm 2. At 2 GHz, the power consumption is 25 mW, of which only 4.7 mW is due to the LO dynamic power.

Keywords

• linearity
• low-noise amplifier (LNA)
• LO generator
• N-path filter
• OOB-IIP₃
• noise figure (NF)