Sub-Volt Fully Balanced Differential Difference Amplifier

Abstract

This paper presents a new CMOS structure for a fully balanced di®erential di®erence ampli¯er (FB-DDA) designed to operate from a sub-volt supply. This structure employs the bulk-driven quasi-°oating-gate (BD-QFG) technique to achieve the capability of an ultra-low voltage operation and an extended input voltage range. The proposed BD-QFG FB-DDA is suitable for ultra-low-voltage low-power applications. The circuit is designed with a single supply of 0.5 V and consumes only 357 nW of power. The proposed circuit was simulated in a 0.18-m TSMC CMOS technology and the simulation results prove its functionality and attractive parameters. An application example of a state variable¯lter is also presented to con¯rm the usefulness of the proposed BD-QFG FB-DDA.

0.5 V Fully Differential Universal Filter Based on Multiple Input OTAs

“…In the open literature, various fully differential voltagemode universal biquad filters are available [10][11][12][13][14][15][16][17][18][19][20]. These filters are based on multiple input fully differential difference amplifier (MI-FDDA) [10], fully balanced differential difference amplifier (FBDDA) [11,12], fully differential difference transconductance amplifier (FDDTA) [13], fully differential difference transconductor (FDDT) [14], fully balanced four-terminal floating nullor (FBFTFN) [15], operational transconductance amplifier (OTA) [16][17][18], second generation fully differential current conveyor (FDCCII) [19][20], and digitally controlled fully differential current conveyor (DCFDCC) [21]. However, the filters in [10,11,12,13,15,21] contain large numbers of passive elements which increase the chip area.…”

“…Some filters [12][13][14][15][16][17][18][19][20][21] operate at high power supply voltage (more than 0.5V) and are not suitable for low-voltage low-power applications. Several filters [10,11,12,13,15,19,20] do not have the feature of electronic tuning of  0 and Q. In [11], the  0 and Q are not orthogonally controlled.…”

“…Several filters [10,11,12,13,15,19,20] do not have the feature of electronic tuning of  0 and Q. In [11], the  0 and Q are not orthogonally controlled. The filters presented in [11,12,13,14,16,17,18,19,20,21] cannot provide five filtering responses, AP, LP, BP, BS and HP functions.…”

“…The filters presented in [11,12,13,14,16,17,18,19,20,21] cannot provide five filtering responses, AP, LP, BP, BS and HP functions. High impedance at input voltage nodes of the fully differential universal filters in [10,11,12,15] is not obtained. Some filters require critical matching conditions [10,11].…”

“…High impedance at input voltage nodes of the fully differential universal filters in [10,11,12,15] is not obtained. Some filters require critical matching conditions [10,11].…”