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previous: Gus the resistor that defines the input... -- 11/24/1999 9:29 PM	View Thread

Re: Some progress made on the hisssssssssssss...

11/24/1999 9:53 PM
Doc	Re: Some progress made on the hisssssssssssss... Is this roughly the input impedance of the circuit? In other words, if you are trying to maintain a high impedance, such as in a tube circuit, you would select FET technology because they have better S/N performance in this region than a bipolar device? Conversely, a bipolar device is basically a low impedance (wrt/ tube circuitry impedance) device, and operates with a better S/N ratio in circuits of nominal impedance 10k and below. When trying to use a bipolar device at higher impedances, it would exhibit a higher noise figure than an FET. Do I have the general idea?

11/24/1999 9:53 PM

Doc

Re: Some progress made on the hisssssssssssss...

Is this roughly the input impedance of the circuit?

In other words, if you are trying to maintain a high impedance, such as in a tube circuit, you would select FET technology because they have better S/N performance in this region than a bipolar device? Conversely, a bipolar device is basically a low impedance (wrt/ tube circuitry impedance) device, and operates with a better S/N ratio in circuits of nominal impedance 10k and below. When trying to use a bipolar device at higher impedances, it would exhibit a higher noise figure than an FET.

Do I have the general idea?

Replies:

Gus Yes. This is explaned in one of th... -- 11/26/1999 4:37 AM
Dave James Thanks Doc, you cleared up my quest... -- 11/30/1999 4:45 PM