Comparison of conventional and new flipped voltage structures with increased input/output signal swing and current sourcing/sinking capabilities

Abstract

A systematic comparison of Flipped Voltage Followers circuits is presented. Two new versions of the flipped voltage follower are introduced. They are characterized by very low output impedance, high bandwidth speed, wide signal swing . All structures can be easily modified for class AB operation . Simulation results show that the newly introduced structures have optimal characteristics.

Class AB flipped voltage follower with very low output resistance and no additional power

“…1d, denominated Folded Flipped Voltage Follower (FFVF) [10]. Here, M1 is replaced with its counter part, maintaining the gate and drain terminal connections -the source terminal is connected to the respective rail.…”

“…, class AB modification of FVF using b) a floating battery [8], and c) a bulk-driven technique [9]. Also shown is d) the Folded FVF (FFVF) [10], e) the proposed class AB version with very low output resistance, and f) the proposed low-voltage version. Fig.…”

Development of Single-Transistor-Control LDO Based on Flipped Voltage Follower for SoC

“…The development of high-performance integrated voltage regulators, in terms of accuracy, power efficiency, response time, silicon area, and off-chip component free feature, is undoubtedly vital to the success of SoC. To enable these requirements, a low drop out (LDO) with single-transistor control (STC) based on the flipped voltage follower (FVF) [1]- [3], with emphasis on the circuit theory for successful implementation, is presented in this paper [4].…”

“…A high loop gain, which results in improved steady-state regulation, degrades close-loop stability, so that different methodologies such as an advanced pole-zero can-cellation scheme in [5], a load-dependent reference voltage concept in [6], pole-splitting schemes in [7]- [10], were proposed. Recently, a super source follower [11], in form of FVF [1]- [3], has been applied to the designs of a buffer [12] and a power stage [13] in LDO. The main advantage of the FVF is the reduced output impedance due to shunt feedback connection [11], which is the key for obtaining good regulation and achieving frequency compensation.…”

“…However, there are, in fact, many design issues have to be studied when using the FVF as a power stage. The studies in [1]- [3] do not focus on LDO design, and the application of the FVF in [12] is not for the power stage. In addition to the impedance control in [13], loop stability is undoubtedly a key issue needed to be analyzed in detail, especially when using different combinations of output capacitor and ESR values [14], [15] or when operating in the no output-capacitor (no-capacitor) condition [7], [8].…”