An Optimized Low-Noise Low-Power Preamplifier for Cardiac Implants

Among various analog circuits, the preamplifier has a prominent role in the analog front end (AFE) circuit of biomedical implantable microsystems for a reliable acquiring of weak biophysiological signals. The AFE acts as an interface between the acquired analog biosignals and the digital part in these implants. As the industry of the biomedical implantable devices develops, lowering the power consumption as much as possible without sacrificing the performance is essential in improving the service time of the battery, which cannot be replaced frequently. Hence, there is an increasing demand for a low noise, low power bio-acquisition system so as to avoid bulky connectivity and reduce patient mobility and discomfort. This paper thus presents an operational transconductance based preamplifier for the application in cardiac implants. The performance of the proposed design was evaluated based on various parameters such as gain, common mode rejection ratio (CMRR), noise spectral density, and power consumption. Besides, optimization by supply voltage scaling of the proposed design was done with the focus is on lowering the power consumption. The trade-offs between various parameters like gain, speed, and power consumption were observed in the optimized design. The preamplifier, designed using a 180nm CMOS technology, provides a high gain of 50dB at a supply voltage of 1.5V and a low power dissipation of 61.10 mu W. Based on the performance evaluation, it was observed that the proposed preamplifier is suitable for low power cardiac applications.