Wake-Up Receiver For Narrowband IoT Applications

A narrowband receiver system, comprising;

• a wake-up receiver;
• and
• a main receiver configured to operate in a high power state and a low power state, wherein the main receiver consumes more power in the high power state than in the low power state and the main receiver transitions from the low power state to the high power state in response to a wake-up signal received from the wake-up receiver;
• wherein the wake-up receiver is powered down during periodic intervals and includes:
• an antenna configured to receive an RF signal;
• a low noise transconductance amplifier interfaced with the antenna;
• a local oscillator;
• a mixer circuit configured to receive the RF signal from the low noise transconductance amplifier and a mixing signal from the local oscillator, where the mixer circuit downconverts frequency of the RF signal to an intermediate frequency;
• a frequency locked loop circuit interfaced with the local oscillator;
• and
• a fractional n phased-locked loop circuit interfaced with the local oscillator.