Voltage amplifier This is called current feedback even though it is a voltage that substracted from the input voltage.Because of the series connection at the input and output,the input and output resistance get increased.This type of amplifier is called transconductance amplifier. A. Voltage-shunt feedback B. Current-series feedback C. Voltage-series feedback D. Current-shunt feedback List-ll 1. 2. Current Shunt. resistance, Zif, and the closed-loop output resistance, Zof of the shunt-shunt configuration shown. I know the input impedance: Ri=ri*(1+A.β) But I dont know how I should find the output impedance. Current amplifier 3. (NOV 2008, NOV 2011) Input Resistance. I am trying to find the output impedance of a series shunt feedback amplifier by converting it to a two port network. The op amp has a differential input resistance of zi, voltage gain of av, and output resistance of zo. It is called a series-derived, shunt-fed feedback. So, the feedback current is a transimpedance block that converts the current … To obtain very high input and output impedances in a feedback amplifier, the topology used is a) Voltage – series b) Current – series • input current I 1 and Voltage Shunt. The input impedance of a current shunt feedback amplifier is the open loop impedance of the amplifier divided by 1+(A*beta) Typically, higher input and lower output impedances are desired for most cascade amplifiers. Compare the input and output resistance of the voltage and current shunt feedback amplifiers. I only know the answer: Ro=ro/(1+A.β). The load current is sampled by placing a small value resistor in series with the load at the collector . Output Resistance. an example of series – shunt feedback The op-amp acts like a voltage amplifier The feedback network samples the output voltage, voltage divides it and feeds back a voltage into the input, so that v in is the sum of input and fed-back v. The feedback network shares with the op-amp (think a finite input impedance!) Both of these are provided using the voltage-series feedback … The feedback circuit connected in series for the output and parallel to the input signal is known as a current shunt feedback amplifier. The voltage across this sampling resistor is made to appear in shunt (parallel) to the input. Trans-resistance amplifier 4. The input resistance of the current - shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 is. The shunt connection at the input reduces the input resistance and the series connection at the output increases the output resistance. If we consider the input voltage and current to be V in and I in and the output voltage and current to be V out and I out, the simplest definitions of the impedances Z in and Z out are given by :. Voltage feedback tends to decrease the output impedance, whereas current feedback tends to increase the output impedance. This is a true current amplifier. the input resistance. R if ... to the load without much loss and it can be easily achieved with the help of of feedback techniques. 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. Whereas the output connected in terms of series makes the value of impedance high. Z in =V in /I in; Z out =V out /I out; Generally, an input impedance is high and an output impedance is low. A current shunt feedback amplifier circuit is illustrated in the figure 1. a) 1/11KΩ b) 1/5Ω c) 5 kΩ d) 11 kΩ 20. Due to the parallel connection with the input the value of impedance is low at this point. Ideal amplifiers have an infinite input impedance and a zero value for the output impedance. Trans-conductance amplifier 2. output resistance of 2.5 kΩ.