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Why we use BJT differential amplifier?
Differential Amplifier using Transistor. A differential amplifier is designed to give the difference between two input signals. The emitters of both T1 and T2 are connected to a common emitter resistor so that the two output terminals V1OUT and V2OUT gets affected by the two input signals I/P1 and I/P2.
Why FET op amps are better than BJT op-amp?
These op amps typically use JFETs for the input differential amplifier stage, with most of the rest of the circuit being bipolar for the reasons others have given in their answers. The advantage of using FETs for the input stage is exactly as you say: they have much higher input impedance.
Are op amps still used?
Op-amps are still a primary building block for analog systems, performing tasks like amplification, active filtering, and signal transformation. In digital systems, op-amps are used in buffers, analog-to-digital converters, digital-to-analog converters, and regulated power supplies, to name a few applications.
Is the BJT differential amplifier a voltage controlled amplifier?
However, as is typical in most amplifiers, the larger signal, the more distorted it gets. Run a few simulations while increasing VS beyond 10 mV. Checkout the THD results appearing in the in the output text file, BJT_DIFFAMP1.OUT. The differential amplifier makes a handy Voltage-Controlled Amplifier (VCA).
How does a differential amplifier follow an op amp?
Simply follow a differential amplifier with another differential amplifier. Or, like in op amp circuits, subtract the collector currents directly using additional transistors to mirror current from one collector to another. ( A future design topic to be sure.)
What is common mode rejection ratio in differential amplifier?
Differential Amplifier using Transistor – Common Mode Effectiveness of rejection depends on the matching of two common – emitter stages used. The ability of a differential amplifier to reject common mode signal is called Common Mode Rejection Ratio (CMRR).
What kind of transistors are used for a differential amplifier?
Differential Amplifier using BJT. The simplest form of differential amplifier can be constructed using Bipolar Junction Transistors as shown in the below circuit diagram. It is constructed using two matching transistors in common emitter configuration whose emitters are tied together.