"Amplifier with feedback (CFB-current feedback) is an electronic circuit (usually presented as an integrated circuit) having two inputs and one output. The output is the difference of the two inputs multiplied by a factor (G) (gain):
The feedback amplifier is an alternative to voltage-feedback amplifiers, also called operational.
The feedback amplifier is an alternative the voltage-feedback amplifiers, also called operational.
negative feedback theory
Definition
general strategy of system design, whereby a magnitude proportional to the system output is subtracted from the reference input .
RN Advantages
reduces system sensitivity to parameter variations.
Increases bandwidth.
reduces nonlinear distortion.
Improves input impedances and output
feedback amplifier configuration
For amplifiers feedback voltage must increase and decrease Rin Rout, so that all the stress that comes from the input signal falls on the amp and all the tension of the output signal falls on the burden placed. In transresistance amplifiers feedback should decrease the lower Rhine and Ro, so that the entire current input signal passes through the amplifier and for the whole amplifier output voltage drop on the load placed. In the case of current feedback amplifiers to decrease and increase Rout Rin, so that the entire current input signal passes through the amplifier and for the entire output current passes through the load placed. And finally in the feedback transconductance amplifiers will increase and increase Ri Ro, for all the tension of the input signal falls on the amp, and that all the output current passes through the load placed.
The feedback increases or decreases Rin and Rout of the amplifiers is more like the ideal case.
feedback Types
feedback in voltage opposes any change in the input signal attempts to change the output voltage to reduce Rout (suitable for power amplifiers and transresistance)
feedback in current opposes the current change, making the output is a constant-current source to increase The Rout (suitable for current and transconductance amplifiers)
The Feedback Series. Is connected in series circuit with feedback amplifier. This increases the input resistance (suitable for amp. Voltage and transconductance).
The Parallel Feedback. Are connected in parallel circuit and the feedback amplifier. This reduces the input resistance (suitable for amp. Transrresistencia current and).
series voltage feedback to voltage amplifier.
current feedback amplifier in parallel to current.
Advantages
The main advantage of development using current feedback amplifiers with high speed is provided. Consequently, it has been shown to increase the speed has the advantage of improved sound. Also, the speed affects the speed in which it may correct the faults that they themselves produce.
The current feedback amplifiers (CFA) is a type of electronic amplifier whose negative input is sensitive to lacorriente, unlike normal amplifiers that they are to stress (VFA).
The CFA was invented about 1988. They are usually produced as integrated circuits with the same pin assignment that VFA, thus allowing the two types can be easily interchanged. In simple configurations, such as linear amplifiers, a CFA can be used in place of a VFA without modifying the circuit, but in other cases, such as integrators need a redesign. The classic configuration of the amplifier with four resistors will also work with a CFA, but the CMRR is very poor.
Mario Dominguez Zambrano EES
Section: 02
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