Channel-Selection LNA Using High-Order $N$ -Path Feedforward Blocker Cancellation Path With Complex Poles for Advanced 5G NR FDD RX

This article presents a channel-selection (CH-SEL) low-noise amplifier (LNA), employing a main common-source (CS) amplifier path and high-order
$N$
-path feedforward (FF) blocker cancellation path for advanced cellular applications. The proposed FF path comprises a mixer-first receiver (RX) using a baseband (BB) amplifier with combined negative and positive capacitive feedback, BB G
$_{m}$
-stage, BB high-pass filter, and current-mode up-conversion mixer. This FF path provides input power matching and exhibits fourth-order
$N$
-path bandpass filtering with BB complex poles at the LNA input and additional notch filtering at the LNA output. It has a higher Q-factor than the second-order
$N$
-path filtering with a BB real pole, achieving a flat passband and improved selectivity with the same 3-dB bandwidth at both the input and output of the LNA. The proposed CH-SEL LNA enhanced the blocker tolerance and linearity of 5G new radio (NR) frequency division duplexing primary and diversity RXs. Fabricated in a 65-nm CMOS process, the CH-SEL LNA achieved a maximum voltage gain of 22.6 dB, minimum noise figure (NF) of 4.4 dB, maximum out-of-band (OB) input-referred third-order intercept point (IIP3) of 23.2 dBm, and notch rejection ratio of more than 23.8 dB. It also covers mid-band (MB) frequencies in a range of 1.35–2.7 GHz for 5G NR cellular applications, exhibits an average current of 21.2 mA from a supply voltage of 1 V, and has an active die area of 0.77 mm
$^{2}$
.