Digital Signal Model

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_2 Course outline Contents Digital Signal ModelDigital Signal Model Non Ideal Behavior of Components High Speed Properties of Digital Gate Ground Planes Crosstalk Power Distribution Terminations Time domain Frequency domain Trapez. pulse (  = 50%, t r = 5 ns) Harmonics (  = 50%, t r = 5 ns) Trapez. pulse (  = 70%, t r = 8 ns) Harmonics (  = 70%, t r = 8 ns)

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_3 Time domain Periodic trapezoidal pulses –A = amplitude –T = period –  = pulse width or duration A/2) –t r = rise time (from 10% to 90% of the transition) –t f = fall time (from 90% to 10% of the transition) –  = duty cycle

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_4 Frequency domain Envelope of Fourier Components (harmonics) –S 0 = (2A  )/T, DC component –f 1 = 1/(  ), first knee –f 2 = 1/(  t r ), second knee If t r  t f, use shortest time valid for  = 50 %

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_5 Trapez. pulse (  = 50%, t r = 5 ns) A = 5 V T = 100 ns t r = 5 ns t f = 5 ns  = 45 ns  = 50 % A  trtr tftf If t r  t f, generally t f is shortest

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_6 Harmonics (  = 50%, t r = 5 ns) S0S0 f1f1 f2f2 S 0 = dB f 1  7.07 MHz f 2  MHz A = 5 V, T = 100 ns t r = 5 ns, t f = 5 ns  = 45 ns,  = 50 % Spectral contribution until 0.5/t r

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_7 Trapez. pulse (  = 70%, t r = 8 ns) A = 5 V T = 100 ns t r = 8 ns t f = 10 ns  = 61 ns  = 70 % A  trtr tftf If t r  t f, generally t f is shortest

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_8 Harmonics (  = 70%, t r = 8 ns) S 0 = dB f 1  5.22 MHz f 2  MHz A = 5 V, T = 100 ns t r = 8 ns, t f = 10 ns  = 61 ns,  = 70 % S0S0 f1f1 f2f2

@ Copyright F. Canavero, R. Fantino 7/6/2017Licensed to HDT - High Design TechnologyDSM_9 Next topic Non Ideal Behavior of Components