A 2.4 GHz Ultra-Low-Power Low-Voltage Temperature-Stable Transmitter for Biosensing Applications

This paper presents a temperature-robust, high energy-efficiency, integrated and low-power transmitter for 2.4 $\mathbf{G H z}$ industrial scientific medical (ISM) band. Fabricated in $\mathbf{6 5}$ nm CMOS process, the proposed transmitter with low pulse-position modulation (LPPM) comprises a subthreshold-leakage-current-compensation relaxation oscillator (RxO) and a ring oscillator (RO) composed of delay units with different temperature characteristics. Power efficiency and temperature stability of the transmitter are improved by the above technology. Supporting LPPM and on-off keying (OOK) modulation at 2.4 GHz, the transmitter for Wireless body area network (WBAN) achieves an output power of $\mathbf{- 1 4. 1} \mathbf{~ d B m}$ with 20 Mbps and 11 Mbps data rate at 0.6 V, respectively. The power consumption of $99.3 \mu \mathrm{~W}$ and energy per bit (EPB) of $9.03 \mathrm{pJ} / \mathrm{bit}$ are measured under LPPM. The frequency variation of temperature compensated RxO and RO are $\mathbf{0. 5 5} \% \sim \mathbf{2. 2 5} \%$ and $-\mathbf{0. 2 3} \% \sim 0.07 \%$, respectively.