A Power Mixer Based Dual-Band Transmitter for NB-IoT Applications

Narrow Band Internet of Things (NB-IoT) technology has played an important role in low-rate and long-range IoT applications. A fully integrated dual-band transmitter (TX) based on a novel power mixer is illustrated in this paper. The power mixer occupies very small chip area using only one balun and achieves low power by operating at class-AB region. In addition, gain-boosting structure is introduced to improve the linearity target: third-order counter intermodulation (CIM3). Implemented in 65 nm RF CMOS technology, the TX combined of a third-order low-pass filter and a power mixer consumes 50 mW at an output power of 0 dBm for low-band (824-915 MHz) and 56 mW at -0.8 dBm for mid-band (1695-1710 MHz). The TX can be configured to show better than -59 dBc CIM3. The error vector magnitude (EVM) of QPSK modulated signal is 1.1% at 0.3 dBm for low-band and 1.3% at -0.8 dBm for mid-band. The overall chip area is only 0.9 mm(2).