What is spot noise factor?
The ratio of (1) the total output noise power per unit bandwidth (spectral density) at a single output frequency when the noise temperature of all input terminations is at the reference noise temperature, T0, at all frequencies that contribute to the output noise to (2) that part of (1) caused by the noise of the …
How is noise figure calculated?
In fact the noise figure is simply the comparison of the SNR at the input and the output of the circuit. There are two basic figures that can be used: Noise factor: The noise factor can be derived simply by taking the SNR at the input and dividing it by the SNR at the output.
What is the noise figure of an amplifier?
Noise figure (NF) and noise factor (F) are measures of degradation of the signal-to-noise ratio (SNR), caused by components in a signal chain. It is a number by which the performance of an amplifier or a radio receiver can be specified, with lower values indicating better performance.
What is the ideal noise figure in dB?
A high value of noise figure indicates system degradation and poor performance. A typical RF system with cellular and ISM applications in the operating range of 400 MHz to 1500 MHz has a noise figure in the range of 0.9 dB in the low gain mode and 2.3 dB in the high gain mode.
Does attenuator reduce noise?
A second motivation for using external attenuators to test low-sensitivity receivers is to reduce the noise density of the test signal. In this scenario, the attenuator reduces both noise power and signal power. As purely passive RF device, attenuators theoretically inject no noise into an RF signal.
What is the best noise figure?
What is a noise in a signal?
In signal processing, noise is a general term for unwanted (and, in general, unknown) modifications that a signal may suffer during capture, storage, transmission, processing, or conversion.
Do attenuators cause reflections?
Improving Amplitude Accuracy As figure 3 illustrates, the external attenuator attenuates the reflection caused by the DUT. As a result, the affect of VSWR will be minimized and amplitude accuracy will be improved.
What is the noise figure of attenuator?
Noise figure of attenuator Noise power at the input of attenuator due to a perfectly matched source at temperature () is given by When a noisy signal pass through the attenuator, noise power gets attenuated in the same way as the signal power.
What is the difference between passive attenuator noise and RF generator noise?
Thus, when Pnoise = -174 dBm/Hz, the noise figure of a passive attenuator is equivalent to its loss. On the other hand, output noise density from an RF generator is caused by active components and will result at levels that are sometimes significantly above the theoretical noise floor.
What is the noise figure?
As described in the equations below, noise figure is simply the logarithmic equivalent of the noise factor measurement. Based on the equations above, it might SEEM that use of an attenuator on the output of a vector signal generator would attenuate the signal strength without attenuating the noise power.
What happens when the attenuator is in thermal equilibrium?
Under the assumption that the attenuator is in thermal equilibrium, no heat flows out on the attenuator due to temperature gradient. The heat dissipated in the attenuator is equivalent to excess noise power () in the attenuator.