This paper reports an ultra-low-voltage (ULV) single-crystal oscillator-timer (XO-Timer) for sub-0.5 V Bluetooth low-energy (BLE) radios that aims for self-powering by harvesting the ambient energies. Specifically, we tailor an on-chip micropower manager $(\mu $ PM) to customize the voltage and current budgets for each sub-function of the XO-Timer. Such $\mu $ PM shows a high power efficiency by introducing a 3-stage cascaded structure and a single voltage-regulation loop; they together uphold the performance of the XO-Timer amid supply-voltage and temperature variations. The core amplifier of the XO-Timer is ULV-enabled, and is reconfigurable (i.e., 1-stage and 3-stage gm) to balance between the power budget and performance under the high-performance mode (HPM) and low-power mode (LPM). Fabricated in 28-nm CMOS, the XO-Timer in HPM generates a 16-MHz clock with a power of $24.3 ~\mu \text{W}$ , and a phase noise of −133.8 dBc/Hz at 1-kHz offset, resulting in a Figure-of-Merit (FoM1) of −236 dBc/Hz. In the LPM, the XO-Timer delivers a 32.258-kHz clock while consuming $11.4 ~\mu \text{W}$ . The sleep-timer FoM2 is $14.8 ~\mu \text{W}$ and the Allan deviation is 35.1 ppb, achieving the lowest supply voltage (0.25 V) not only for a dual-mode XO-Timer but also for a MHz-range XO.

中文翻译：

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超低电压单晶振荡器定时器（XO 定时器）为 28 纳米 CMOS 中的低于 0.5 伏能量收集 BLE 无线电提供 16 MHz 和 32.258 kHz 时钟

本文报告了一种用于低于 0.5 V 蓝牙低功耗 (BLE) 无线电的超低电压 (ULV) 单晶振荡器定时器 (XO-Timer)，旨在通过收集环境能量实现自供电。具体来说，我们定制了一个片上微功耗管理器 $(\亩$ PM) 为 XO-Timer 的每个子功能定制电压和电流预算。这样的 $\亩$ PM通过引入3级级联结构和单稳压环路表现出高功率效率；它们共同支持 XO-Timer 在电源电压和温度变化情况下的性能。XO-Timer 的核心放大器支持 ULV，并且可重新配置（即 1 级和 3 级 gm）以平衡高性能模式（HPM）和低功耗模式下的功率预算和性能（LPM）。HPM 中的 XO 定时器采用 28 纳米 CMOS 制造，可生成功率为 16 MHz 的时钟 $24.3 ~\mu\text{W}$ ，以及 1 kHz 偏移时的 −133.8 dBc/Hz 相位噪声，导致 −236 dBc/Hz 的品质因数 (FoM1)。在 LPM 中，XO-Timer 提供 32.258-kHz 时钟，同时消耗 $11.4 ~\mu\text{W}$ . 睡眠定时器 FoM2 是 $14.8 ~\mu\text{W}$Allan 偏差为 35.1 ppb，实现了双模式 XO 定时器和 MHz 范围 XO 的最低电源电压 (0.25 V)。