Continuous Time Analog Design for Very Low Frequency Applications

For an Operational Transconductance Amplifier- Capacitor (OTA-C) integrated circuit implementation, this directly translates to a very small transconductance (of the order of a few nA/V) and a very large on-chip capacitance (of the order of several hundred pF). Both the above mentioned aspects of low frequency IC design are addressed in this work. Specifically, a family of OTA' s with very small transconductance has been designed using several design schemes such as current division, use of floating gate MOS and bulk driven transistors. A detailed comparison has been made among these schemes in terms of performance characteristics such as power consumption, active silicon area and signal to noise ratio. A multiplier based OTA with very small transconductance has also been designed with a view to obtain a wide transconductance tuning range. Moreover, an impedance scaling circuit has also been designed in order to realize very large capacitors on-chip. As sample applications for these circuits, a low pass filter, relaxation oscillator, band pass filter and a band pass based oscillator have also been designed, fabricated in a 1.2um analog process and successfully tested in the lab.

Anand Veeravalli completed his BE in Electrical Engg from BITS, Pilani in India (1998) and his MSEE from TAMU, College Station, US by specializing in analog design under the esteemed AMSC center (2001). Since then, he has been working with Texas Instruments as a senior analog designer, a position which he holds and relishes immensely till this day.