Current shunt feedback amplifier is the type of negative feedback amplifier in which the part of the output current is applied in parallel with the input current. The current feedback operational amplifier (CFOA or CFA) is a type of electronic amplifier whose inverting input is sensitive to current, rather than to voltage as in a conventional voltage-feedback operational amplifier (VFA). In addition to reading the questions and answers on my site, I would suggest you to check the following, on amazon, as well: Question Bank in Electronics & Communication Engineering by Prem R Chadha c.) Current Series Feedback Amplifier. A current series feedback amplifier can be used as local negative feedback to increase input resistance, linearize the transfer curve, and stabilize bias. The gain without feedback is: $$A=\frac{I_o}{V_i}=\frac{-h_{fe}}{h_{ie}+R_E}$$ and the feedback factor is: $$\beta=-R_E$$ The output impedance should then be: $$Z_{of}=Z_o(1+A\beta)=Z_o(1+\frac{R_Eh_{fe}}{h_{ie}+R_E})$$ This is a different result compared to finding the Thevinin equivalent resistance looking back into the output which just gives the output … in this f/b amplifier, the o/p current is proportional to the developed voltage. Current amplifier circuit. In this type of circuit, a portion of the o/p voltage is applied to the i/p voltage in series through the feedback circuit. Current shunt feedback amplifier is the type of negative feedback amplifier in which the part of the output current is applied in parallel with the input current. Reduction in input resistance in case of voltage shunt and current shunt type amplifiers. In single stage amplifiers, input and output impedance depeds mainly on the amplifier configuration used. The block diagram of the current series feedback-amplifier is shown below, by which it is apparent that the feedback circuit is located in series by means of the output as well as the input. A useful approximation to the precise result is that the input or output impedance is equal to the source or load impedance for … It is employed in voltage amplifiers. Table 3.2.1 compares basic input and output impedances for single stage voltage amplifiers (common emitter) and current… Series-Series Feedback Amplifier (Current-Voltage FB) • For a transconductance amplifier (voltage input, current output), we must apply the appropriate feedback circuit – Sense the output current and feedback a voltage signal. The feedback in which the feedback energy i.e., either voltage or current is out of phase with the input and thus opposes it, is called as negative feedback. Abstract: A simple and precise method is given for calculating the input and output impedances of a feedback amplifier, directly from its loop gain. 9.1 Basic Amplifiers. Abstract: A simple and precise method is given for calculating the input and output impedances of a feedback amplifier, directly from its loop gain. Increase in output resistance in case of current shunt and current series feedback amplifiers. b)Current series: Output signal is current signal, feedback signal is voltage signal. Also called as shunt-series feedback. The basic amplifier, figure 9.1, has two ports and is characterized by its gain, input impedance and output impedance. a)Voltage-series: Output signal is voltage signal, feedback signal is voltage signal. The current feedback operational amplifier (CFOA or CFA) is a type of electronic amplifier whose inverting input is sensitive to current, rather than to voltage as in a conventional voltage-feedback operational amplifier (VFA). The Series Resistor Method. An ideal amplifier has infinite input impedance (R in = ∞), zero output impedance (R out = 0) and infinite gain (A vo = ∞) and infinite bandwidth if desired. The amplifier uses voltage feedback, but even if, somehow, current feedback had been used, speed would still be limited by the output stage. Input Impedance, Z IN or Input Resistance as it is often called, is an important parameter in the design of a transistor amplifier and as such allows amplifiers to be characterized according to their effective input and output impedances as well as their power and current ratings. The higher the resistance with respect to the speaker impedance, the purer the amplifier operates in the current-drive mode. Then the “series-series feedback configuration” functions as transconductance type amplifier system as the input signal is a voltage and the output signal is a current. Shunt-Shunt Feedback Systems So, the feedback current is a transimpedance block that converts the current signal into a voltage. Other XFCB amplifiers, with emitter-follower output stages (VF or CF), are much faster than the AD8041.