Types Of Feedbacks PDF

FeedBack Connection types FEEDBACK CONNECTION TYPES There are four basic ways of connecting the feedback signal. Both voltage and current can be fed back to the input either in series or parallel. Specifically, there can be: 1. Voltage-series feedback 2. Voltage-shunt feedback 3. Current-series fe...

FeedBack Connection types FEEDBACK CONNECTION TYPES There are four basic ways of connecting the feedback signal. Both voltage and current can be fed back to the input either in series or parallel. Specifically, there can be: 1. Voltage-series feedback 2. Voltage-shunt feedback 3. Current-series feedback 4. Current-shunt feedback In the list above, Voltage refers to connecting the output voltage as input to the feedback network; Current refers to tapping off some output current through the feedback network. Series refers to connecting the feedback signal in series with the input signal voltage; Shunt refers to connecting the feedback signal in shunt (parallel) with an input current source. Voltage-Series Feed back Voltage-shunt feedback Current-series feedback Current-shunt feedback Summary of Gain, Feedback, and Gain with Feedback Voltage-Series Feedback connection with a part of the output voltage feed back in series with the input signal, resulting in an overall gain reduction. If there is no feedback (Vf = 0), the voltage gain of the amplifier stage is Input Impedance with Feedback Output Impedance with Feedback Current-Series Feedback The output impedance with current-series feedback can be determined by applying a signal V to the output with V s shorted out, resulting in a current I , the ratio of V to I being the output impedance. Current-Series Feedback Effect of Feedback Connection on Input and Output Impedance 1. Determine the voltage gain, input, and output impedance with feedback for voltage-series feedback having 𝐴 = −100, 𝑅𝑖 = 10𝑘𝛺, 𝑎𝑛𝑑 𝑅0 = 20𝑘Ω for feedback a β = −0.1 and b β = −0.5. (𝑎) 𝐴 𝐴𝑓 = 𝐴𝑑 1 + 𝛽𝐴 𝐶𝑀𝑅𝑅 = 𝐴𝑐 −100 𝐴𝑓 = 𝐴𝑑 1 + (−0.1)(−100) 𝐴𝑐 = 𝐶𝑀𝑅𝑅 𝐴𝑓 = −9.09 30000 𝐴𝑐 = 31622.7766 𝑨𝒄 = 𝟎. 𝟗𝟓 𝑻𝑯𝑨𝑵𝑲 𝒀𝑶𝑼