A Clockless Temperature-Compensated Nanowatt Analog Front-End for Wake-Up Radios Based on a Band-Pass Envelope Detector

Abstract

This paper presents an Analog Front-End for integrated Wake-Up Radios. The proposed Analog Front-End is composed of an envelope detector, a Schmitt trigger and a biasing block and has three distinctive features: i) clockless solution, which does not require an always-on oscillator; ii) an envelope detector with band-pass response which leads to smaller capacitance, thus easier integration, and low-frequency noise suppression; iii) temperature compensated biasing scheme. An active scheme for the detector is used based on MOSFETs operated in the subthreshold region with a self-biased topology. Advantages and drawbacks of the proposed architecture are analyzed. A prototype was fabricated in the STMicroelectronics 90-nm BCD technology. The overall power consumption, excluding the biasing block, is 36 nW at 1.2 V. A 10 -3 Bit Error Rate is measured with a 771-MHz, 2-kbit/s OOK modulated input signal with -46 dBm power at room temperature and at -20 °C, and with almost -43 dBm power at 60 °C.

Design and Characterization of an Active Low-Pass Envelope Detector for Wake-Up Radio Receivers

“…Recently, rectification is often performed through passive diode chains, which are known to have better sensitivity performances thanks to the lack of flicker noise [3]- [5]. However, active implementations have also been chosen throughout the years for the following advantages [6]- [8]: i) smaller area thanks to the absence of a separated baseband amplifier, ii) a wider input power dynamic range, iii) a natively higher input resistance and lower input capacitance, thus making the design of an effective matching network easier, and iv) the availability, depending on the specific ED topology, of a threshold generated by the ED itself for the subsequent decision circuit. This paper focuses on an active ED which can be implemented as a band-pass (BP) or a low-pass (LP) circuit.…”

“…This paper focuses on an active ED which can be implemented as a band-pass (BP) or a low-pass (LP) circuit. As a matter of fact, a first comparison between these two options is carried out in [8] but only results for a BP ED are given. On the other hand, [9] presents results for a prototype in the STMicroelectronics 90-nm BCD technology implementing a LP ED but mostly covers the BBL.…”

A Schottky-Diode-Based Wake-Up Receiver for IoT Applications

“…The second architecture utilizes a frontend with tuned-RF filter and LNA [7]- [8] which achieves high sensitivity at the expense of the power consumption of the LNA. The third architecture eliminates the mixer and LNA and uses a square-law detector as an energy detector [9]- [14]. The envelop detector has the same structure as the square-law and are interchangeable, however we the term ED for large signal detection whereas for small signal detection we use squarelaw or energy detector.…”

“…The envelop detector has the same structure as the square-law and are interchangeable, however we the term ED for large signal detection whereas for small signal detection we use squarelaw or energy detector. This architecture can be designed with high-latency [11]- [14] and low data rate (<1kbps) which in turn results in low power and high sensitivity due to the reduced bandwidth. Alternatively, designs targeting lowlatency applications [16] have also been shown to run at high data rates (>50kbps) and moderate sensitivity.A digital correlator would benefit the 3 architectures, however it would have maximum benefit when applied for square-law detector based architecture…”

Splitting Receiver with Multiple Antennas

“…The conventional receiver schemes can be categorized into two classes: coherent-detection (CD) receiver and non-coherent detection receiver, where envelope detection (ED) and power detection (PD) are the most commonly-used detection mechanisms for non-coherent receivers [4]- [6]. For the CD receiver, the received radio frequency (RF)-band signal is converted to a complex (i.e., in-phase and quadrature) baseband signal by using a down-conversion circuit.…”