Digitally intensive transmitter employing RF pulse width modulation for IoT applications

A CMOS RF-PWM transmitter with a Class-D power amplifier (PA) is proposed for Internet of Things (IoT) applications. The transmitter utilizes two PLL-based PWM generators to convert baseband signals into an RF-PWM signal without an upconverter. For an LTE signal with a 1.4 MHz bandwidth and a 6.4 dB peak-to-average ratio (PAR), the RF-PWM transmitter achieves a power-added efficiency (PAE) of 17.5%, an error vector magnitude (EVM) of −24.9 dB, and an adjacent channel leakage ratio (ACLR) of −31 dBc at an average output power of 16.1 dBm. The transmitter achieves a peak output power of 22.4 dBm with 46.6% PAE, and 38.8% efficiency for the full RF-PWM transmitter including PAs.