A 45 <formula formulatype="inline"><tex Notation="TeX">$\mu$</tex></formula>W Injection-Locked FSK Wake-Up Receiver With Frequency-to-Envelope Conversion for Crystal-Less Wireless Body Area Network

Abstract

A dedicated ultra-low power fully integrated FSK wake-up receiver (WuRx) for wireless body area network (WBAN) is implemented in 0.18 m CMOS technology with 0.7 V supply voltage. For low power consumption, a body channel communication (BCC) physical layer (PHY) is adopted with an 80 MHz carrier frequency. Moreover, an injection-locking digitally-controlled oscillator (IL-DCO) is used to provide an extraordinary gain and frequency-to-envelope conversion in the simple and power-efficient envelope detection receiver architecture. The IL-DCO plays an important role in amplifying and demodulating the received FSK signal under a tight power budget. Finally, for low system cost without any external components and calibration overhead, a successive approximation register (SAR) auto-calibration algorithm is proposed to promptly calibrate the frequency drift of the IL-DCO. As a result, the fabricated 1 mm single-chip WuRX consumes 45 W with a data rate of 312 kb/s, providing an 80 MHz reference frequency with 0.25% stability within 102 s calibration time. The proposed WuRX delivers a stable reference clock to the main transceiver for crystal-less WBAN applications.

Simultaneous High-Efficiency Power Delivery and Energy-Efficient Forward Data Transmission Over Single Inductive Link

“…In this paper, we utilized ILROs to realize the FSK-ASK conversion for simple and low-power consumption demodulation. This technique has been widely used in demodulation and frequency generation as it has obvious advantages in low-power applications [27], [28], [29]. The basic principle of ILRO is shown in Fig.…”

“…5. A free-running ring oscillator (RO) with a frequency of f 0 is injected with a signal of frequency f inj , when f inj is in the locking range (f 0 -f L < f inj < f 0 + f L ), the output envelope of RO is constant, whereas in the injection pulling range (f inj < f 0 − f L or f inj > f 0 + f L ), the output envelope has the amplitude modulation phenomenon [29]. For studies on the injection locking range f L , see [30], which is outside the scope of this paper.…”

“…where A 0 is the output amplitude of the oscillator on the free operation and K is a constant, determined by the load charge and discharge. Unlike exploiting the difference in RO output envelope characteristics between the injection-locked and injection-pulled states in [29] and [31], we take advantage of the constant envelope characteristics in the injection-locked range to achieve FSK-ASK conversion. Therefore, our design makes the injection frequencies f inj all lie within the injection-locked range.…”

Area-Efficient Integrated Current-Reuse Feedback Amplifier for Wake-Up Receivers in Wireless Sensor Network Applications

“…A unique solution to avoid the need to include PLLs is to use a tuned oscillator as a frequency-to-amplitude conversion block to extract FSK-modulated data from the incoming signal [26]. This is the principle behind the injection-lock architecture [27][28][29]. If the carrier frequency of the input signal is close to the LO frequency, coupling between both signals occurs and a single frequency appears at the output.…”

“…The receiver shows a sensitivity of -80/-78/-77 dBm under OOK/FSK/PSK modulation schemes at a data rate of 200 kbps. Additionally, an injection-locking digitally controlled oscillator is introduced in [28], reporting a sensitivity of -62 dBm for a data rate of 312 kbps, operating at 80 MHz with a power consumption of 45 µW.…”