0.8 V bulk-driven operational amplifier

Abstract

A low-voltage bulk-driven CMOS operational amplifier is proposed in this paper. The inherent small transconductance of the bulk-driven devices is enlarged using a positive feedback, improving also the noise performance. The amplifier is designed using standard 0.18 lm n-well CMOS process. Although the amplifier is optimized for 0.8 V supply voltage, it is also capable to operate under supply voltage of 0.7 V. The amplifier consumes 130 lA, performing 56 dB open-loop gain, 154 nV/HHz input-referred spot noise at 100 kHz, 80 dB CMRR at 100 kHz and IIP3 equal to -4.7 dBV.

Novel CMOS Bulk-driven Charge Pump for Ultra Low Input Voltage

“…where f is the switching frequency and α is technology parameter that expresses a ratio between parasitic (C s ) and nominal capacitance (C in ) of the selected capacitor that is given by (6).…”

“…Recently, this technique has been used for design of basic building blocks of analog and digital integrated circuits (IC), e.g. operational amplifier [6], [7], current mirrors [8], [9], current converter [10], [11], operational transconductance amplifier (OTA) [6], [12], voltage follower [13], [14], voltage to current converter [15], voltage controlled oscillator [16], phase locked loop (PLL) [17], etc.…”

An ultra high-speed high-resolution low-offset low-power voltage comparator with a reliable offset cancellation method for high-performance applications in 0.18 µm CMOS technology

“…Fortunately, in CMOS technologies where the float N-well regions introduce an additional connection as the bulk node of the PMOS devices along with the prior gate, source and drain nodes, more facilities arise. Although, some approaches have been reported about bulk-driven circuits [10,11], in most cases, practical operation of the ideas are doubted. In this paper a reliable structure is presented as an offset cancellation method which benefits from the bulk-driven facilities in a feasible way.…”

A transconductance enhancement technique for bulk-driven OTAs working in weak inversion

“…In recent years, many methods to increase the effective transconductance (G m ) in bulk-driven have been developed [4,5,6,7,8]. The partial positive feedback technique has been adopted by several recent works [1,5,6,9] and some other papers improve the transconductance (g m ) by using an auxiliary amplifier [8,10], where the enhancement ratio of transconductance is improved yet there is still the room for enhancement. This paper proposes a transconductance enhancement technique for bulk-driven OTAs working in weak inversion by utilizing an auxiliary amplifier and positive feedback technique, which enhances the enhancement ratio of transconductance from ðn þ 1Þ=ðn À 1Þ to ðn þ 2Þ=ðn À 1Þ with just a little increased power consumption.…”