========================IRDA===================================== 500_mW/cm^2 = 500_mW/sr@ 1cm sr =sterradians Radian_Sensitive_Area_mm^2 7_mm^2 \ | / |\ Max_power_mW _____ \ | / | \ ___\ | | | ___ LED ___ \ | ___ > 8.75_mW _|_ / | Max_Idiode / | \ \| / ^ \ | 4.4_mA / | \ /_\ / V <---20mm---> |_____| Max_power_mW/sr Spect_Sensitive_uA/uW 500_mW/sr 0.5_uA/uW Max_power_mW = 500_mW/sr*(7mm^2/(20m)^2) Radian_Sensitive_Area_mm^2 \ | / |\ Min_power_mW _____ \ | / | \ ___\ | | | ___ LED ___ \ | ___ > 0.04_uW _|_ / | Min_Idiode / | \ \| / ^ \ | 0.14_uA / | \ 7_mm^2 /_\ / V |_____| Min_power_mW/cm^2 Spect_Sensitive_uA/uW 0.4_uW/cm^2 0.5_uA/uW Radian_Sensitive_Area_mm^2 \ | / |\ Sun_power_mW _____ \ | / | \ ___\ | | | ___ SUN ___ \ | ___ > 7mW _|_ / | Sun_Idiode / | \ \| / ^ \ | 3.5mA / | \ 7_mm^2 /_\ / V |_____| Sun_power_mW/cm^2 Spect_Sensitive_uA/uW 1mW/cm^2 0.5_uA/uW ^ 5V /|\ | re_ohms= .026/Idc = 2600_ohms _| ____|' NPN I_shot_A/rt(Hz) = sqrt(q*2*Idc) | |`-> I_shot = 1.7pA/rt(Hz) _|_ | 10uA V_shot = 4.65_nV/rt(Hz) /// / | \ V V_therm_nV /rt(Hz)=4*sqrt(R/1K_ohm) 1Mohm / V_therm = 126.5_nV/rt(Hz) \|/ V -10.7V ^ 5V /|\ | _| ____|' NPN | |`-> re_ohms= 2600_ohms _|_ _|_ /// / \ V_shot = 4.65_nV/rt(Hz) \___/ __ |____| | 10uA | |__| V_shot(2.6K) = 4.65_nV/rt(Hz) | / NOTE ! V \ V_therm(2.6K)= 6.44_nV/rt(Hz) / 1Mohm _|_ / \ V_therm = 126.5_nV/rt(Hz) \___/ | | \|/ V -10.7V re_ohms= 2600_ohms ____________ _|_ | _|_ /// | / _ \ _|_ \/ \/ | I_shot = 1.7pA/rt(Hz) \ / /\_/\ V _V_ \___/ ___ |_______|____| | V_shot = 4.65_nV/rt(Hz) _|_ |___| / _ \ 10uA \/ \/ | /\_/\ V \___/ | \|/ V -10.7V _____ ___\ | | | ___ >.043pW/rt(Hz) _|_ / | Noise_Idiode / ^ \ | .021pA/rt(Hz) /_\ / V |_____| Noise_power_W/rt(Hz) Spect_Sensitive_uA/uW .043pW/rt(Hz) 0.5_uA/uW Dark_Current 2nA ________________ | _|_ _|_ _|_ / _ \ / _ \ ^ | \/ \/ \/ \/ Dark_shot_I=.025pA/rt(Hz) /_\ | /\_/\ /\_/\ | V \___/ \___/ |_______|________| Noise_Floor_Dark = Dark_shot_I*SQRT(BandWidth_Hz) = .025pA/rt(Hz)*SQRT(10_MHz) = .075nA_@10MHz Noise_Floor_Sun = Sun_shot_I*SQRT(BandWidth_Hz) = 34pA/rt(Hz)*SQRT(10_MHz) = 106nA_@10MHz Noise_Floor_LTC = 1.79pA/rt(Hz)*SQRT(10_MHz) = 5.6nA_@10MHz If I_signal >> I_noise .. jitter is low (spec +/1%) Want Bit_Error_Rate (BER) less than 10^-8 _______ | | C_diode=C_zero/(1-V_diode/phi)^M _|_ __|__ ^ _____ C_zero_pf = 72 /_\ | phi_mV = 700 | | M = .45 |_______| C_diode_@2V = 40pF Start Stop bit <----------Data_Perfect_Signal------------> bit _ _ lsb_ _ _ _ _ _ _ msb | | | | | | | | | | | | | | | | | | | | _| |__| |__| |__| |__| |__| |__| |__| |__| |__V__V || <---Jitter-> || Defined at rising edge _ _ _ _ _ _ | | | | | | | | | | | | | | _| |_| |___| |________| |___________| |__| |__V__V ^ Measured Signal /|\ |____ Used as reference TEST PATTERNS for Jitter 01111111 7F 01010101 5A 00001111 0F 00110011 33 01110111 77 01000000 40 00000000 00 distance 0 to 1meter Signal Modulation Pulse Jitter BW_MHz Rate 115.2kb/s RZI 1.63us +/-445n 5 1.152Mb/s RZI 217ns +/-56n +/-25ns 4Mb/s 4PPM 125ns +/-10n +/-10ns 100 ____ _________ ____ | 1 | 0 0 | 1 1 | 0 | 1 | 0 NRZ _| |_________| |____| |____ ^ ^ ^ ^ ^ ^ ^ ^ ^ Transmit a infared when ever a zero. _ _ _ _ | | | | | | | | ________| |__| |____________| |_______| |____ 1.152Mb/s ^ ^ ^ ^ ^ ^ ^ ^ ^ expect +/-12.5ns jitter from 40MHz clock and +/-5ns jitter LED and driver _________ _________ | 1 | 0 0 | 1 | ___| |___________________| |_______ 4Mb/s ^ chip1 ^ chip2 ^ chip3 ^ chip4 ^ <--------------Dt=500ns----------------> Data Bit Pair 4PPM Data (DBP) Symbol(DD) 00 1000 01 0100 10 0010 11 0001 noise peaking interference filtering tail simulations