Portable and wireless functional near-infrared spectroscopy is a growing field of research for real-time monitoring of brain functions. The most critical challenges in this field are the use of low-power and calibrated circuits. A novel transmitter architecture is proposed to overcome these barriers. This transmitter is low power, capable of being calibrated against process variation, and has a better phase noise and spurious-free dynamic range (SFDR) at the antenna. Besides that, the transmitter can be calibrated, which is not seen in similar research. In this transmitter, injection locking and frequency calibration lead to having an optimal and low-power circuit. The circuit is capable of transmitting data with BFSK and OOK modulations in the frequency band of the medical implant communication service (MICS). The transmitter is designed and simulated in a typical CMOS 0.18-μm technology with a 1-V power supply. The transmitter's power consumption is around 146 and 123 μW, equal to 5.92 nJ/bit and 246–630 pJ/bit for BFSK and OOK modulations, respectively. The signal's phase noise at the antenna is almost −109 dBc/Hz at 1-MHz frequency offset.

中文翻译：

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用于无线 CW-fNIRS 系统的最佳次谐波注入锁定 MICS 波段发射机

便携式和无线功能性近红外光谱是实时监测大脑功能的一个不断发展的研究领域。该领域最关键的挑战是使用低功耗和校准电路。提出了一种新颖的发射机架构来克服这些障碍。该发射器功率低，能够针对过程变化进行校准，并且在天线处具有更好的相位噪声和无杂散动态范围 (SFDR)。除此之外，还可以对变送器进行校准，这在同类研究中是没有的。在该发射器中，注入锁定和频率校准导致具有最佳和低功耗电路。该电路能够在医疗植入通信服务 (MICS) 的频带中使用 BFSK 和 OOK 调制传输数据。发射器采用典型的 CMOS 0.18-μm 技术设计和仿真，电源为 1-V。发射器的功耗约为 146 μW 和 123 μW，分别等于 BFSK 和 OOK 调制的 5.92 nJ/bit 和 246–630 pJ/bit。天线处的信号相位噪声在 1 MHz 频率偏移时几乎为 −109 dBc/Hz。