Lecture #6 - Dynamic Range and Sensitivity Flashcards
What is dynamic range?
The difference between smallest and largest input or output signal power for which a component or system has desirable characteristics.
How can the dynamic range of the component be specified?
- Linear dynamic range
- Spurious free dynamic range
Explain what LDR is
LDR is the difference between the largest and smallest signal output power, while the component is being driven in the linear operating range.
- Largest signal o/p power is limited by the 1dB compression point
- Smallest signal o/p limited by noise floor
What are meant by suprious tones?
- Nonlinearity of active RF components results in harmonics and intermodulation products.
- Narrowband devies and bandpass filters with high stop band attenuation -> harmonics can be filtered.
- IM3 products located in desired passband and cannot be removed. –> spurious tones
What is the lower limit of SFDR defined by
The o/p power of the fundamental signal is equal to the noise floor.
What is the upper limit of SFDR defined by
The largest signal power is limited by the o/p power level of an IM3 product.
What does it mean that the SFDR is smaller than the LDR
Indicates that the presence of IM products can distort the fundamental o/p signal much before the device under test goes into compression (experiences non-linearity).
Why do we want an o/p signal power to exceed the noise floor by a certain amount
When the signal just barely hits the noise (o/p power signal = noise floor); it means that SNR is 0dB.
What is a minimum detectable signal?
The output signal power should exceed the noise floor by a certain amount. (SNR > 0dB)
What is sensitivity?
The minimum input signal power that a receiver can detect for a given output SNR is called sensitivity.
What happens if the input power has to be higher to be detected means for the reciever?
It has a lower sensitivity.
Why use noise temperature and why does NF always assume?
A temperature of 290 degree kelvin
