What does ultra low noise mean in amplifiers?
Various types of ultra-low noise amplifiers both for DC and AC signals are described. “Ultra- low noise” here means that voltage noise density is bellow 1 nV/√Hz for AC amplifiers or noise less than 100 nVpp for DC amplifiers. 1. Ultra–low noise AC amplifiers Op amplifiers (OA) are widely used as AC amplifiers.
Which is the best preamplifier for low gain?
The best ones all were high-voltage power transistors. My favorites up now are BF459 or MJE13007. BF459 is better when current noise matters, i. e. impedances like dynamic microphones and low gains. MJE13007 produces less voltage noise, but much more current noise and is better for low-impedance sources like ribbon microphones and high gains.
What should the voltage be for very low noise?
Very low noise was meant to be 1.5 nV/Sqr(Hz) or less. I thought this should be easy as usual ICs like the INA103 provide as low as 1.0 nV/Sqr(Hz) voltage noise. But I was wrong.
What is the input noise of an amplifier?
– The input voltage noise of the Amplifier (UNoiseIn) – The positive input current noise multiplied by the impedance of the signal source (RSourcex INoisePosIn) – The negative input current noise multiplied by the source resistance of the feedback resistor divider ((R1parallel to R2) x INoiseNegIn)
How does low impedance affect the output noise?
It is interesting to remark that in such a configuration it is essentially the noise current that would affect the output noise; the input voltage noise is effectively shorted by the low impedance at the opamp inverting input.
Which is the best relay for low noise?
There’s not much to tell about construction; just use good quality components (polypropylene caps, metal film resistors) and low noise opamps (AD797 or LT1115, LT1128, LME49710, OPA211 on a SMD adaptor) and the good results are guaranteed. The relays are DIP case 12V models.
Is it possible to beat the 0.4nv / rthz noise?
To beat the 0.4nV/rtHz noise, we have to abandon the Colin architecture; not only is the 10 ohm source resistor eating up the entire noise room (it already has 0.4nV/rtHz Johnson noise by itself) and going down would require much larger RIAA caps in the input stage, but also directly paralleling more than 4x2SK170 is not practically feasible.