26.9 A 0.038mm2 SAW-less multiband transceiver using an N-Path SC gain loop

N-path filtering has been intensely rekindled as a replacement of costly SAW filters, making possible of multiband blocker-tolerant receivers (RXs) at small area and power, e.g., [1]. This paper proposes an N-Path Switched-Capacitor (SC) Gain Loop that is reconfigurable as an RF-tunable transmitter (TX) or RX with LO-defined center frequency. Comparatively, a SAW-less RX should be able to amplify a weak in-band (IB) signal in the presence of large out-of-band (OB) blockers, whereas a SAW-less TX should be able to deliver a large IB signal with low spectral leakage and OB noise. Such discrepancy inspires exploration of an RX-TX-compatible N-path technique to realize a multiband transceiver (TXR) with zero on-chip inductors and external matching components. Our TXR aims at the multiband LTE standard, and comparable performances are achieved at a die size 24× smaller than the recent art [2, 3].