This paper presents system level design and measurements of a novel 2.4 GHz low-power and low-data-rate receiver, which uses Barker-coded Binary Phase-shift keying (BPSK) along with Pulse Position Modulation (PPM) as a communication scheme. To achieve low-power dissipation levels, direct-detection receiver architecture is used in combination with a 13-bits Barker Code Surface Acoustic Wave (SAW) correlator to improve co-channel interference. Furthermore, in order to improve receiver sensitivity, the baseband bandwidth is reduced by means of an innovative Narrowband Correlator (NBC), which allows for scalable receiver sensitivity versus data-rate. The receiver can be used as a Wake-up Receiver (WuRx) in Wireless Sensor Networks (WSNs) to minimize the power dissipation and provide asynchronous and on-demand data communication. The receiver is designed using TSMC65n technology and achieves a power dissipation of 142μW from 1.2V supply source and sensitivity of −44 and −50dBm at a data-rate of 2 Mbps and 600 kbps respectively.