Voltage Follower / Buffer Calculator

A voltage follower is a unity gain buffer that produces an output voltage equal to its input voltage. It provides high input impedance and low output impedance, making it ideal for impedance matching between circuits.

Voltage followers prevent loading effects between circuit stages, provide current amplification while maintaining voltage levels, and offer isolation between sensitive input circuits and varying load conditions.

Op-amp followers offer near-perfect unity gain and very high input impedance, while transistor followers (BJT/JFET) have slightly less than unity gain but can handle higher currents and offer simpler, lower-cost implementations.

Input impedance of a BJT emitter follower is approximately β × (RE + re), where β is current gain, RE is emitter resistance, and re is the dynamic emitter resistance (about 26mV/IE at room temperature).

While ideal voltage followers have unity gain (1.0), practical circuits have slightly less due to finite open-loop gain in op-amps or the emitter resistance in transistor configurations, typically ranging from 0.95 to 0.999.

BJT followers offer higher current gain and lower output impedance but require base current. JFET followers provide very high input impedance with no gate current but have temperature-dependent characteristics and lower transconductance.

Op-amp followers typically have output impedance of 0.1-1Ω, BJT emitter followers around 10-100Ω (depending on β and RE), and JFET source followers range from 100Ω to several kΩ depending on transconductance.

Yes, voltage followers provide significant current amplification while maintaining voltage unity gain. Op-amp followers can source/sink substantial current, and transistor followers provide current gain equal to β (BJT) or effectively infinite gain (JFET).