Patent attributes
A Bluetooth Low-Energy (BLE) transmitter is presented for used in ultra-low-power radios in short range IoT applications. The power consumption of state-of-the-art BLE transmitter has been limited by the relatively power-hungry local oscillator due to the use of LC oscillators for superior phase noise performance. This disclosure addresses this issue by analyzing the phase noise limit of a BLE TX and proposes a ring oscillator-based solution for power and cost savings. The proposed transmitter features: 1) a wideband all-digital phase locked loop (ADPLL) featuring an fRF/4 RO, with an embedded 5-bit TDC; 2) a 4× frequency edge combiner to generate the 2.4 GHz signal; and 3) a switch-capacitor digital PA optimized for high efficiency at low transmit power levels. These not only help reduce the power consumption and improve phase noise performance, but also enhance the transmitter efficiency for short range applications.
