Low Noise Power Amplifier

The Curiously Low Noise Amplifier takes benefit of the wonderful blast characteristics of the 2SK170 JFET to facilitate boasts a clamor voltage underneath 1 nV/burrow-Hz and practically rejection racket current. The noise voltage of the amplifier is just 1.4 nV/root-Hz by the side of 1 kHz, increasing to only 2.7 nV/delve-Hz by 10 Hz. The blare current is awkward to quantity, so this undemanding benefit amplifier can notice the clamor from a 50 ohm resistor and a 100k resistor, too. (The 1.4 nV input-referred clamor command rise to re 1.7 nV with a 50 ohm resistor, as an alternative of a sharply, and a 100k resistor will bequeath an input-referred racket approaching 40 nV, with very small contribution from the amplifier.)

This amplifier is a "service" amplifier with a secure of 100, with the purpose of would typically occur used at home a lab setting to boost tiny signals on behalf of measurement or else added doling out. It isn't intended to drive a spokesperson or else headphones in a straight line. (It may well drive the LM386 quite nicely.) The circuit is a minimal discrete transistor view circuit with two grow stages and a unique panache-A output buffer stage:

Low Noise Power Amplifier