A class‐AB flipped voltage follower cell with high symmetrical slew rate and high current sourcing/sinking capability

Abstract

SummaryThe paper presents a class‐AB flipped voltage follower (FVF) cell based on quasi‐floating gate and bulk‐driven techniques. The quasi‐floating gate technique is used to increase the current sinking capability, whereas the bulk‐driven technique is used to enhance the current sourcing capability by reducing the threshold voltage. Using these two techniques, the proposed class‐ AB FVF cell offers high current sinking and sourcing capabilities. Also, it provides high symmetrical slew rate without any additional circuitry. The physical layout of the proposed class‐ AB FVF cell has been designed in Cadence Virtuoso Layout XL editor using BSIM3v3 180‐nm CMOS technology, and post‐layout simulation results have been presented to validate its performance. The corner analysis of the proposed class‐ AB FVF cell has also been performed with temperature and supply voltage as design variables to show its performance under extreme conditions.

High-performance flipped voltage follower based low input resistance current mirror with wide current mirroring range and high output resistance

“…Using equations ( 20) and ( 21), we get v d8 (s) = g m5 g m8 v d1 (s) (g m7 + sC A )(g m9 + sC B ) (27) Using equations ( 18), ( 25), ( 26) and (27), the output current i out (s) is written as i out (s) = ( g m12 g m13 (g m4 + sC gs4 )(g m7 + sC A )(g m9 + sC B ) + g m5 g m8 g m10…”

“…But these techniques suffer from the limitation of special fabrication steps. The flipped voltage follower (FVF) cell is another useful technique that is extensively used in analog circuits to make them work at low supply voltage [26][27][28][29][30]. Basically, FVF cell is an improved version of voltage follower as it is cascode amplifier with negative feedback and unity gain.…”

A high output resistance, wide bandwidth, and low input resistance current mirror using flipped voltage follower cell

“…Due to the various advantages of the class-AB FVF cell 32 such as low output resistance, high current driving capability, and low voltage operation, it is considered as a basic building block for the proposed current sensor. The proposed current sensor is shown in Figure 1, in which the transistors M 1 to M 7 form the class-AB FVF cell and transistor M 8 copies the current of transistor M 2 .…”

“…The characteristics of class-AB FVF cells are low output resistance, symmetrical slew rate, large voltage swing, high current sourcing/sinking capabilities, and wide bandwidth. Recently, the class-AB FVF cell based on the quasi-floating gate and bulk-driven techniques has been reported, 32 which shows enhanced current driving capability without an increase in the area. The quasi-floating gate technique enhances the current sinking capability, and the bulk-driven technique increases the current sourcing capability of the reported circuit.…”