CMOS Circuit Design, Layout, and Simulation, Second Edition
CMOS Circuit Design, Layout, and Simulation, Second Edition
Design of Analog CMOS Integrated Circuits
Design of Analog CMOS Integrated Circuits
An ultra-low power RF interface for wireless-implantable microsystems
Microelectronics Journal
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This paper proposes a novel structure of ASK (amplitude shift keying) demodulators, which requires no external capacitors, for implantable micro-stimulators. By using a traditional @b multiplier reference to detect the signal envelope, followed by a Schmitt trigger and a load driver, the large off-chip capacitor in traditional ASK demodulators is not required any more. Therefore, the proposed circuit possesses small area to be integrated in an SOC (system-on-chip). Besides, due to the lack of the large capacitor, the proposed circuit can operate with a higher data rate using lower frequency carriers. The proposed circuit is integrated in an implantable micro-stimulator on silicon using 0.35@mm 2P4M CMOS process. The area of the proposed circuit occupies merely 0.039mm^2 with a maximum power dissipation of less than 12mW (including the power consumption of the analog circuits of the micro-stimulator) by measurement results on silicon. Moreover, the measurement results verify that the proposed ASK demodulator can detect the ASK modulated signal up to 570kbps data rate at 2MHz carrier frequency when the modulation index is 10%.