This question was previously asked in

UGC NET Paper 2: Electronic Science June 2019 Official Paper

Option 1 : 83 dB

Official Paper 1: Held on 24 Sep 2020 Shift 1

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50 Questions
100 Marks
60 Mins

__Concept:__

Maximum dynamic range is defined for different orders is

\(MD{R_3} = \frac{2}{3}\left( {DANL - TOI} \right)\)

\(MD{R_2} = \frac{1}{2}\left( {DANL - SOI} \right)\)

\(TOI = Mixer\;level - \frac{{dBc}}{2}\)

SOI = Mixer level – dBc

Optimum mixer level = DANL – MDR

Attenuation = Signal – Optimum Mixer level

MDR_{3}: Maximum third-order dynamic range

MDR_{2}: Maximum second-order dynamic range

TOI: Third Order Intercept

SOI: Second Order Intercept

DANL: Displayed Average Noise level

Mixer level = signal level - attenuation

__Calculation:__

Given TOI is 30 dB and the noise level is – 95 dB

Dynamic range is

\(MD{R_3} = \frac{2}{3}\left( { - 95 - \left( {30} \right)} \right)\)

\(MD{R_3} = \frac{2}{3}\left( { - 125} \right)\)

**MDR _{3} = - 83.33 dB**

Taking the magnitude the answer is option 1

__Extra Explanation:__

**Dynamic Range Graph**

- The above graph is about the distortion products as a function of mixer power, we can also plot the signal-to-noise ratio (SNR) as a function of mixer power.
- The signal-to-distortion curves tell us that the maximum dynamic range for distortion (minimum distortion in dBc) occurs at a minimum power level to the input mixer.

Dynamic range can be represented graphically

Maximum dynamic range occurs where the curves intersect, that is, when the internally generated distortion level equals the displayed average noise level. This shows two of the dynamic range specifications.

**The optimum mixer level occurs at the point of maximum dynamic range.**