Low Noise Low Power CMOS Telescopic-OTA for Bio-Medical Applications

Abstract

The preamplifier block is crucial in bio-medical signal processing. The power intensive Operational Transconductance Amplifier (OTA) is considered, and the performance of preamplifier is studied. A low noise and low power telescopic OTA is proposed in this work. To reduce the noise contribution in the active load transistors, source degeneration technique is incorporated in the current stealing branch of the OTA. The OTA design optimization is achieved by g m / I d methodology, which helps to determine the device geometrical parameters (W/L ratio). The proposed design was implemented in CMOS 90 nm with bias current and supply voltage of 1.6 µA and 1.2 V, respectively. The post layout simulation results of the proposed amplifier gave a gain of 62 dB with phase margin 57°, CMRR 78 dB, input referred noise 3.2 µVrms, Noise Efficiency Factor (NEF) 1.86 and power consumption of 1.92 µW.

Keywords

• low noise preamplifier
• telescopic OTA
• source degeneration
• current stealing
• CMOS 90 nm
• gm/Id methodology
• subthreshold