A Microwatt Low Voltage Bandgap Reference for Bio-medical Applications

Abstract

In this paper a microwatt low voltage bandgap reference suitable for the bio-medical application. The Present technique relies on the principle of generating CTAT and PTAT without using any (Bipolar Junction Transistor) BJT and adding them with a proper scaling factor for minimal temperature sensitive reference voltage. Beta multiplier reference circuit has been explored to generate CTAT and PTAT. Implemented in 45nm CMOS technology and simulated with Spectre. Simulation results shows that the proposed reference circuit exhibits 1.2% variation at nominal 745mV output voltage. The circuit consumes 16uW from 0.8V supply and occupying 0.004875mm2 silicon area.

A 0.55 V Bandgap Reference with a 59 ppm/°C Temperature Coefficient

“…Spot noise at 1MHz is 10 -15 V 2 /Hz and integrated noise in the frequency of interst is 3.98μV. The noise level achieved is more than sufficient for bio-medical transcivers circuits, such as 8-bit ADC and Variable Gain amplifier(VGA) bias circuits [7]. Fig.…”

“…To combat the problem described above and make it suitable for ultra-low power applications without requiring any special devices, several MOS only BGRs implementations have been introduced [5][6][7][8]. To understand their advantage in comparison to BJT-based implementations, one has to understand that the main difference between BJT and MOS reference circuits is that the former relies on the energy bandgap of the silicon (EG~1.2eV).…”

“…The implementations [5][6][7][8] rely on the fact that VGS of the MOS transistor decreases with temperature, hence it is a CTAT, and the difference in the VGS of two transistors is PTAT. These implementations however, show significant power supply sensitivity and use higher power, though their power dissipations in general is still much less than BJT-based implementations.…”

A Start-up Assisted Fully Differential Folded Cascode Opamp

“…This was achieved by making transistor M3 wider (connecting several in parallel) and transistor M4 longer (several in series). The start-up circuit's literature does not include any discussion regarding the inclusion of hysteresis [12] [14]. Whenever there is leakage from devices (in modern technologies) start-up circuits could also be stuck at a potential depending on the leakage level.…”

A High-Performance Skin Impedance Measurement Circuit for Biomedical Applications

“…The frequency response of the impedance can be expressed as (12) and shows its low-frequency value is R 1 +R E and high-frequency value goes down to R 1 due to the capacitor [12]. It has a pole and zero in the frequency response as given in (13). Fig.…”