If we connect the output of an op-amp to its inverting input and apply a voltage signal to the noninverting input, we find that the output voltage of the op-amp closely follows that input voltage (I’ve neglected to draw in the power supply, +V/-V wires, and ground symbol for simplicity): As Vin increases, Vout will [...]
Sponsored Link :
Article2
OPERATIONAL AMPLIFIERS : part 5 (An analogy for divided feedback)
A helpful analogy for understanding divided feedback amplifier circuits is that of a mechanical lever, with relative motion of the lever’s ends representing change in input and output voltages, and the fulcrum (pivot point) representing the location of the ground point, real or virtual. Take for example the following noninverting op-amp circuit. We know from [...]
Article3
OPERATIONAL AMPLIFIERS : part 4 (Divided feedback)
If we add a voltage divider to the negative feedback wiring so that only a fraction of the output voltage is fed back to the inverting input instead of the full amount, the output voltage will be a multiple of the input voltage (please bear in mind that the power supply connections to the op-amp [...]
Article4
Transistors : Feedback
If some percentage of an amplifier’s output signal is connected to the input, so that the amplifier amplifies part of its own output signal, we have what is known as feedback. Feedback comes in two varieties: positive (also called regenerative), and negative (also called degenerative). Positive feedback reinforces the direction of an amplifier’s output voltage [...]
Article5
OPERATIONAL AMPLIFIERS : part 11 (Positive feedback)
As we’ve seen, negative feedback is an incredibly useful principle when applied to operational amplifiers. It is what allows us to create all these practical circuits, being able to precisely set gains, rates, and other significant parameters with just a few changes of resistor values. Negative feedback makes all these circuits stable and self-correcting. The [...]
Article6
transistors : Biasing calculations
Although transistor switching circuits operate without bias, it is unusual for analog circuits to operate without bias. One of the few examples is “TR One, one transistor radio” TR One, Ch 9 with an amplified AM (amplitude modulation) detector. Note the lack of a bias resistor at the base in that circuit. In this section [...]
