Homework Cover Sheet

Name: Date:Course: EGCP-541 HW #: 7

Grading Criteria:Problem Earned Points Possible Points

Problem 1: 11Problem 2: 9

Total: 0 20

PLEASE UPLOAD YOUR HOMEWORK IN TITANIUM. NO PAPER SUBMISSIONS.

Professor Comments:

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1. (11 Points) Repeat example 6.2 in the book if C1 is changed to 1pF and a 1GHz clock frequency is used. Estimate the frequency where the output of the digital filter is -3 dB (0.707) from the input signal. Verify your answer using the spectrum. Use the LtSpice model for the NS modulator shown below which is available on TITANium (“Prob_1.asc”). I need the final schematic and the spectrum showing that you have attenuation (might be more than 3dB because of filter).

HINTS: a. The -3dB frequency occurs when the imaginary component of the pole (jωRC) is

equal to the real component in the pole (1), or at f=1/2πRC.b. Use this -3dB frequency as the cutoff of the lowpass reconstruction filter to

determine the correct C value given RF 1=500Ω.

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2. (9 Points) Simulate the operation of the NS matched resistor modulator seen below but using a 4-bit quantizer (ADC). Use a 100MHz clock frequency and an input sinewave at 500kHz. You can access the template on TITANium (“Prob_2.asc”). I need the final schematic and the time domain plot of Vin vs. Vout.

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