cfa to vfa
CONVERSION AND SIMULATION OF VFOA TO CFOA
DESIGN AND SIMULATION
Abstract
The need for high speed, wideband amplifiers was the driving force behind the development of the CFA. The CFA has significant advantages over VFA in terms of slew rate performance and inherently wide bandwidth. A faster slew rate will result in a quicker rise time, lower slew-induced distortion and nonlinearity and a wide range of signal frequency response.
This paper provides a review of the Op-amp theory and a deep analysis of the design and simulation of current feedback amplifiers and its applications. Various conventional amplifier circuits are converted to CFA and are supported with calculations and simulated results. The software used for simulation is ICAP.
I. Introduction
Analog design has historically been dominated by voltage mode signal processing. This is apparent in the electronics industry where the Voltage Feedback Amplifier (VFA) has become ubiquitous. The lesser-known Current Feedback Amplifier (CFA) has a fundamentally different architecture and offers significant performance advantages over the traditional VFA. The current feedback operational amplifier or CFB op-amp is a type of electronic amplifier whose inverting input is sensitive to current, rather than to voltage as in a conventional voltage-feedback (VFB) operational amplifier. They are usually produced with the same pin arrangements as VFB op-amps allowing the two types to be interchanged without rewiring when the circuit design allows. In simple configurations such as linear amplifiers a CFB op-amp can be used in place of a VFB op-amp with no circuit modifications but in other cases such as integrators a different circuit design is required. The current feedback amplifier (CFA) has the same ideal closed-loop equations as the voltage feedback amplifier (VFA), but the CFA offers three improvements when compared with the VFA. Generally, CFA’s cost is less per megahertz of bandwidth, and they don’t have the
DESIGN AND SIMULATION
Abstract
The need for high speed, wideband amplifiers was the driving force behind the development of the CFA. The CFA has significant advantages over VFA in terms of slew rate performance and inherently wide bandwidth. A faster slew rate will result in a quicker rise time, lower slew-induced distortion and nonlinearity and a wide range of signal frequency response.
This paper provides a review of the Op-amp theory and a deep analysis of the design and simulation of current feedback amplifiers and its applications. Various conventional amplifier circuits are converted to CFA and are supported with calculations and simulated results. The software used for simulation is ICAP.
I. Introduction
Analog design has historically been dominated by voltage mode signal processing. This is apparent in the electronics industry where the Voltage Feedback Amplifier (VFA) has become ubiquitous. The lesser-known Current Feedback Amplifier (CFA) has a fundamentally different architecture and offers significant performance advantages over the traditional VFA. The current feedback operational amplifier or CFB op-amp is a type of electronic amplifier whose inverting input is sensitive to current, rather than to voltage as in a conventional voltage-feedback (VFB) operational amplifier. They are usually produced with the same pin arrangements as VFB op-amps allowing the two types to be interchanged without rewiring when the circuit design allows. In simple configurations such as linear amplifiers a CFB op-amp can be used in place of a VFB op-amp with no circuit modifications but in other cases such as integrators a different circuit design is required. The current feedback amplifier (CFA) has the same ideal closed-loop equations as the voltage feedback amplifier (VFA), but the CFA offers three improvements when compared with the VFA. Generally, CFA’s cost is less per megahertz of bandwidth, and they don’t have the
References: [1]. Texas Instruments “Current Feedback Op Amp Analysis [2] Phillip E. Allen & Douglas R. Holberg , “CMOS Analog Circuit Design” [3] John Keown, South Polytechnic State University , “MicroSim PSpice and Circuit Analysis”