What is input dynamic resistance?
The dynamic resistance is the resistance offered by the p-n junction diode when AC voltage is applied. When forward biased voltage is applied to a diode that is connected to AC circuit, an AC or alternating current flows though the diode.
Does dynamic resistance increase or decrease with temperature?
Concept: The dynamic resistance can be defined from the I-V characteristic of a diode in forward bias. It is defined as the ratio of a small change to voltage to a small change in current, i.e. ∴ The dynamic resistance of the diode is directly proportional to the temperature.
How is input resistance related to output resistance?
The closed-loop input resistance is effectively ( Ri ‖ Rf )/ (1 + GH ). The effect of negative feedback on output resistance can be analyzed by representing the output as a Thévenin equivalent voltage source with internal voltage of v and open-loop output resistance of Ro. An output voltage of vo is produced by a current io applied to the output.
Why is input resistance larger in noninverting circuit?
For the noninverting op-amp circuit of Fig. 3.6a, the effective op-amp differential input resistance is made larger by feedback. Since v− tracks v+ as feedback, the differential voltage across the input terminals is the error voltage.
Which is the ideal input resistance for an amplifier?
If the voltage source resistance rs is variable or unknown, the attenuation of the divider and the overall voltage gain will be too. To avoid this, the ideal amplifier input resistance is infinite, so vin = vi independent of rs. FIG. 2.4. Amplifier input and output loading for (a) voltage and (b) current amplifiers.
Why does V− produce a smaller input resistance than VI?
Since v− tracks v+ as feedback, the differential voltage across the input terminals is the error voltage. This small voltage produces a much smaller current in the op-amp input resistance than vi alone would produce (with v− grounded).