Sine wave Oscillators

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1-Design a colpitts oscillator to deliver 30 mw in to a 4 k Ω load at 3.5MHz .The oscillator will use a 1.5 μ H coil with Q=160 and a transistor with β=50 and Co=4 p F .It must operate from a 20-V power supply. Specify all resistors and capacitors and determine The minimum power and frequency ratings that the transistor must have. 2-A common-base Colpitts oscillator circuit is desired to tune over the range 1 to 2 MHz .it is to deliver 25m W in to a load 3k. Parts readily available are an air cored coil with Lt=50 μ H and Q =150 over the frequency range and variable capacitor that can tune over a range Cf =30-300p F.Available transistors have Co=10 p F and cut off frequency of 100MHz, and adequate power dissipation capabality. (a) How much power does the transistor have to dissipate. (b) Find

CQI ,CQV .

(c) Will the capacitor Cf be able to to tune the oscillator over the desired range. (d) Solve for the value of L that will result in tuning range exactly 1 to 2 MHz as Cf is varied from 30to300p F? 3-A particular crystal oscillator circuit operates with the crystal in the parallel mode.then a lossless inductor is added in parallel with the crystal is required to have the same reactance as the crystal originally did ,will the oscillator frequency go up or down ?