Low-Voltage Bulk-Driven Operational Amplifier With Improved Transconductance

Sub-threshold, cascode compensated, bulk-driven OTAs with enhanced gain and phase-margin

“…(10) provides weak inversion transconductance, g m (WI) for bulk and source shorted condition as given in Eq. (11) …”

“…G. raikos, S. Vlassis have implemented 100% positive feedback at gate terminals of bulk-driven input pair to enhance its transconductance [6]. Many other authors have suggested partial positive feedback to enhance the transconductance and GBW for bulk-driven pair [7][8][9][10][11][12][13][14][15][16] and this partial-regeneration increases the current drive capability of low bias current ( o150 nA) based sub-threshold circuits. Though the BD-MOST approach overcomes the need of V TH (0.5 V), yet it requires MOST compliance voltage equal to that of gatedriven circuits.…”

“…The PMOS input core structure provides reduced flicker noise as compared to NMOS based design. In addition to this the PMOS input design trends favors standard single n-tub CMOS technology, in which the PMOSTs can be fabricated in isolated bulk, avoiding the need of complex and costly twin-tub CMOS process technology [10,11].…”

Low Power Circuit Design Techniques: A Survey

“…A numerous circuits based on this technique targeted to achieve low power can be found. Few are based on op-amp design [15], high gain op-amp [16], highly linear OTA [17] etc.…”

A Novel MDAC Suitable For A 14B, 120MS/S ADC, Using a New Folded Cascode OP-AMP

“…Bulk driven cascode and folded cascode op amps are typically designed to overcome the signal swing problem [4]. Recent works utilize bulk driven transistors operating in weak inversion to obtain low voltage and low power amplifiers [5]. However the bulk driven topologies still suffer from the reduction in g mb /g m problem especially in the nanometer CMOS technologies.…”