Author: Shahaboddin Moazzeni
Publisher:
Published: 2017
Total Pages: 138
ISBN-13:
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Wake-up receiver (WuRx) is a well-known approach for optimizing the latency and power consumption of ultra-low power transceivers in wireless sensor nodes.Tuned RF (TRF) or Envelope Detection architecture is an appropriate topology for short-range Wireless Body Area Network (WBAN) applications, where achieving a very high sensitivity is not a priority. However, the demand for an improved sensitivity gets emphasized for longer transmission ranges. Regardless of the application, considering the existing trade-off between the power and sensitivity, design techniques and novel architectures are usually employed to optimize the power-sensitivity product. Moreover, considering the negative impact of higher data rate on the sensitivity, the energy-sensitivity product can be a more reasonable figure of merit when comparing WuRx designs.In this thesis, the RF-subsampling architecture has been combined with the TRF receiver architecture as a first approach for improving the power-sensitivity product. The overall power consumption is reduced as a result of employing the subsampling topology with a low-frequency local oscillator (LO). Post layout simulations show that the proposed WuRx draws only 56 oA from a 0.5 V supply and exhibits an input sensitivity of -70 dBm for a data rate of 100 kbps. The chip occupies an area of 0.15 mm2 and is fabricated with TSMC 90nm CMOS technology. Another major contribution of this work is to propose and implement a novel dual-mode ultra-low-power WuRx based on the subsampling topology, which not only reduces the overall power consumption but also optimizes the energy-sensitivity product of the receiver. During the typical mode of operation known as the Monitoring (MO) mode, the start frame bits are received at a rate of as low as 10 kbps. Having received the true preamble bits in the MO mode, the remaining wake-up pattern bits are received at a higher rate of 200 kbps during the Identifier (ID) mode. By lowering the gain of the front-end amplifier in the MO mode, the power dissipation is reduced, which in turn causes an increase in the overall noise figure of the receiver. However, adequate sensitivity and hence an optimized energy-sensitivity product is maintained by intentionally lowering the data rate as well as the detection bandwidth of the receiver in the MO mode. The proposed wake-up receiver has been designed and fabricated in IBM 130 nm technology with a core size of about 0.2 mm2 for the target frequency range of 902-928 MHz. The measured results show that the proposed dual-mode receiver achieves a sensitivity of -78.5 dBm and -75 dBm while dissipating an average power of 16.4 æW and 22.9 æW during MO and ID modes, respectively.
