What is differential input stage?

What is differential input stage?

A differential amplifier is used as the input stage emitter coupled logic gates and as switch. When used as a switch, the “left” base/grid is used as signal input and the “right” base/grid is grounded; output is taken from the right collector/plate.

What is meant by differential gain?

Differential gain is a specification that originated for video applications. More correctly, differential gain is the change in the color saturation level (amplitude of the color modulation) for a change in low frequency luma (brightness) amplitude. …

What is the purpose of differential amplifier stage in op-amp?

Differential amplifiers are used mainly to suppress noise. Noise consists of typical differential noise and common-mode noise, of which the latter can easily be suppressed with an op-amp.

What is the purpose of input stage?

The task of the input stage is to process the differential signals present at the inputs of the operational amplifier while keeping the amount of interference that is added by the input stage as small as possible. Interference includes offset, noise, and distortion.

What is output stage?

The main purpose of the output stage of an operational amplifier is to deliver a certain amount of signal power into a load with acceptably low levels of signal distortion. In a low-voltage low-power environment, this has to be achieved by efficiently using the supply voltage as well as the supply current.

When to use differential stage in differential amplifier?

The output from a differential amplifier is itself often differential. If this is not desired, then only one output can be used, disregarding the other output. Or to avoid sacrificing gain, a differential to single-ended stage can be used following the differential stage.

Can a differential signal be fed to a balanced input signal?

The two inputs at the bases or gates can be fed with a differential or balanced input signal and the two outputs from the collectors or drains remain balanced, or one input could be grounded to convert a single ended input signal to a differential output.

Can a differential amplifier be implemented with a BJT?

The differential amplifier can be implemented with BJTs or MOSFETs. A differential amplifier multiplies the voltage difference between two inputs (Vin+ – Vin-) by some constant factor Ad, the differential gain.

What happens to the emitter voltage in differential mode?

At common mode, the emitter voltage follows the input voltage variations; there is a full negative feedback and the gain is minimum. At differential mode, the emitter voltage is fixed (equal to the instant common input voltage); there is no negative feedback and the gain is maximum.