Chapter 14

Noise Analysis


Noise analysis is run in conjunction with an AC analysis, and calculates the output noise and equivalent input noise in a circuit. The output noise, at a specified output node, is the root mean square sum of the noise generated by all the resistors and semiconductors in the circuit. If the circuit is considered as noiseless, then the equivalent input noise is defined as the noise required at the input to generate the same output noise. This is the same as dividing the output noise by the gain of the circuit to obtain the equivalent input noise. Johnson noise or thermal noise is due to the random thermal agitation of electrons in a conductor, which increases with frequency and temperature. In PSpice, the thermal ...

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