ULP Sliding-IF Receiver With 25% Duty Passive Mixer and Enhanced LO Feed-Through Rejection

This article reports a high-sensitivity ultralow-power receiver (RX) for a long-distance Internet of Thing (IoT) applications. In the RX front end, current reused two-stage low-noise amplifier (LNA) and first mixer that enhances local oscillator (LO) feed-through rejection (FTR) is proposed. The second mixer employs a passive configuration that operates as a 25% mixer, based on a 50% duty cycle LO signal, thereby further minimizing current consumption. Additionally, an analysis of the impact of switching sequence on conversion gain in the passive mixer is presented. Implemented in 65-nm CMOS achieves the sensitivity of −102 dBm at a 0.1%-bit error rate and less than −50-dB carrier-to-interferer ratio (CIR) at 5-MHz offset while consuming $466~\mu $ W from a 0.6-V supply.