A 254-nW 20-kHz On-Chip RC Oscillator With 21-ppm/°C Minimum Temperature Stability and 10-ppm Long Term Stability.

This paper presents a temperature compensated RC oscillator (TC-RCO) designed in 130 nm CMOS technology using regular VTH transistors. The TC-RCO uses constant transconductance gm biasing for first order temperature compensation. Device mismatch based offset correction and delay compensation techniques in the comparator are used to improve temperature instability by cancelling out second order effects. The oscillator achieves a minimum temperature stability down to 21 ppm/°C for a temperature range of -20 to 100 °C. In the lowest power mode, the oscillator consumes 254 nW power with a 1 V supply. The TC-RCO is operated in two modes, a low power mode that consumes an average of 254 nW and a high stability mode that consumes an average of 345 nW. A duty-cycling technique is used to correct offset after four cycles of oscillation. The oscillator exhibits long term stability of 10 ppm after 1 s integration time.

A ±0.5dB, 6nW RSSI Circuit with RF Power-to-Digital Conversion Technique for Ultra-low Power IoT Radio Applications.

This paper presents a new technique of radio frequency (RF) signal strength detection with a received signal strength indicator (RSSI) circuit which can be deployed in an internet-of-things (IoT) network. The proposed RSSI circuit is based on a direct conversion of RF to digital code indicating the signal strength. The direct conversion is achieved by the repeated switching of a rectifier's output voltage using an ultra-low power comparator. A 5-bit programmable feedback circuit is used to correct detection inaccuracies. The RSSI circuit is implemented in a 65-nm CMOS process and consumes 6nW power. It has a linear dynamic range of 26dB and exhibits an error of ±0.5dB with a wide bandwidth of 750MHz. A detailed analysis of the RSSI circuit is presented and verified with simulation and measurement results. The high detection accuracy with ultra-low power consumption of our RSSI circuit is favourable for IoT applications including localization, beamforming, hardware security and other low-power applications.

Ultra-compact dual-band smart NEMS magnetoelectric antennas for simultaneous wireless energy harvesting and magnetic field sensing.

Ultra-compact wireless implantable medical devices are in great demand for healthcare applications, in particular for neural recording and stimulation. Current implantable technologies based on miniaturized micro-coils suffer from low wireless power transfer efficiency (PTE) and are not always compliant with the specific absorption rate imposed by the Federal Communications Commission. Moreover, current implantable devices are reliant on differential recording of voltage or current across space and require direct contact between electrode and tissue. Here, we show an ultra-compact dual-band smart nanoelectromechanical systems magnetoelectric (ME) antenna with a size of 250 × 174 µm2 that can efficiently perform wireless energy harvesting and sense ultra-small magnetic fields. The proposed ME antenna has a wireless PTE 1-2 orders of magnitude higher than any other reported miniaturized micro-coil, allowing the wireless IMDs to be compliant with the SAR limit. Furthermore, the antenna's magnetic field detectivity of 300-500 pT allows the IMDs to record neural magnetic fields.