0.25V Bulk Driven Variable Gain Amplifier using gmb/Idrain Method for Ultra-Low Power Low Voltage Biomedical Applications

The ultra-low power and low voltage is a significant requirement for the portable biomedical instrument. This paper proposed the bulk driven variable gain amplifier for the analog front end of digital hearing aid. The class AB operational Transconduce(OTA) Amplifier with bulk driven inputs is used with a non-tailed differential amplifier. Also graphical method g mb /I drain is used for designing aspect ratio of MOS transistor which is simplest compared to the analytical method. The total power dissipation is 6.5nW for a gain level at a gain of 31dB. The simulation is performed using SPICE in 0.18µm CMOS technology with supply voltage 0.25V.