Nanowatt-Power-Level Automatic Switch Combining ED-CMOS Circuit and LED

Fumiyasu UTSUNOMIYA  Takakuni DOUSEKI 

Publication
IEICE TRANSACTIONS on Electronics  Vol.E95-C  No.6  pp.1104-1109
Publication Date: 2012/06/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
automatic switch,  nanowatt power,  multi-Vth CMOS,  LED,  wireless mouse, 

Full Text: PDF(3.2MB)

Summary: 
A nanowatt-power-level automatic switch that combines a multi-Vth CMOS level converter and an LED as a photodiode has been developed for a sensor application. The level converter is a single-input latch-type multi-Vth CMOS circuit featuring the use of an enhancement-mode nMOSFET and a depletion-mode common-gate nMOSFET as a pair of driver transistors. The ED-CMOS level converter cuts the DC current path; and the LED, which generates a high output voltage under illumination, suppresses the leakage current of the depletion-mode common-gate nMOSFET in the ED-CMOS level converter, resulting in nanowatt-order power dissipation. To verify the effectiveness of the ED-CMOS circuit, a prototype level converter was fabricated on a 0.6-µm CMOS process and used in an automatic switch in a wireless mouse. The switch is composed of two LEDs, a current-mirror circuit, the level converter, and a power switch MOSFET. It senses when a hand grabs or releases the mouse and automatically turns the mouse on or off, respectively. The measured power dissipation of the mouse is 3 nW in the standby mode.