Useful Information: Miscellaneous
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ENAMELLED WIRE

enamel thickness = 0.015*log(d)+0.0194 mm   (minimum 0.004mm)

  where d = wire diameter (mm)

ref. Reference Data for Radio Engineers, 5th edition, p. 6-2
(curve fit to Table 1)

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INTERMODULATION

2IM = 2*2H  (2H + 6.0dB)
3IM = 3*3H  (3H + 9.5dB)

ref. Single Tone Intermodulation Testing
Steve Winder, RF Design December 1993

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RECTANGULAR PULSES & SPECTRUM

rectangular pulses, width T -> spectrum sinc(w*T)
waveform sinc(t/T) -> rectangular spectrum width w = 1/T

i.e. for NRZ bit rate = f, 1st null at f

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A/D CONVERSION

Signal to Noise for a full-scale sinewave

            FS      (2^(b-1)*q)
 Signal = ------  = -----------
          SQR(2)      SQR(2)

             q
 Noise  = -------
          SQR(12)

 S/N    = 2^(b-1) * SQR(6)

   where  FS = full scale input
          q  = LSB size
          b  = number of bits

 S/N(dB) = 6.02*b + 1.76 + 10*log(fs/(2*BW))

   where  fs = sample rate
          BW = signal bandwidth

Signal to Noise due to aperture jitter

                 [    1     ]
 SNR(dB) = 20*log[----------]
                 [2*PI*fm*Ta]

   where Ta = rms aperture jitter
         fm = max. spectral component

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PULSE OPERATION OF LEDS

 peak current = d^(-0.7) * dc

  where d  = duty cycle
        dc = dc current rating

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I/O CHARACTERISTICS OF LOGIC GATES

HC/HCT

 input capacitance 3pF typ, 10pF max
 o/p Vcc-0.2V @ 4mA, 0.17V @ -4mA         min at 25 degC
 o/p Vcc-1V  @ 17mA,    1V @ -17mA        typ

AC/ACT

 input capacitance 4.5pF typ
 o/p Vcc-0.64V @ 24mA, 0.36V @ -24mA      min at 25 degC
 risetime 3nS

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RISETIME

Equivalent cosine waveform

 v = -cos(2*PI*3.388/t)

  where v = voltage
        t = 10% to 90% risetime 

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RISETIME & TRANSMISSION LINE EFFECTS

Delay above which transmission line effects need to be allowed for
(applies for series lines and stubs)

 delay = risetime/3

  where delay = 3.34 nS/m in air
              ~ 6 nS/m Epoxy-glassfibre microstrip

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SHOT NOISE

 in = SQRT(2*q*I)

  where in = current noise (A/root Hz)
        q  = electron charge
        I  = DC current

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DIODE CHARACTERISTICS

Volt-equivalent of temperature

 VT = k*T/q

  where k = Boltzmann constant
        T = Temperature (K)
        q = electron charge

Reverse saturation current

 I0 = K*T^m*e^-(VGO/(n*VT))

  where K   = constant (function of device geometry and material)
        m   = 1.5 for Si, 2.0 for Ge
        VGO = 1.21V for Si, 0.785V for Ge
        n   = eta, 2 for Si (1 at large currents), 1 for Ge

Current - voltage relationship

 I = I0*(e^(V/(n*VT))-1)

 V = n*VT*ln(1+I/I0)

Variation with temperature

 dV/dT = (V-(VGO+m*n*VT))/T

ref. Integrated Electronics, Millman & Halkias, p. 751

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JUNCTION CAPACITANCE

Abrupt junction (e.g. transistor emitter-base)

            1
 C = k * -------
         (V+V0)^(1/2)

Linearly graded junction (e.g. transistor collector-base)

            1
 C = k * -------
         (V+V0)^(1/3)

  where k  = constant
        V  = reverse bias voltage
        V0 = barrier voltage (~0.6V)

ref. Integrated Electronics, Millman & Halkias, p. 65

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MOSFET ON-RESISTANCE

Temperature coefficient typ +0.35 to +0.5 %/degC


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QUARTZ CRYSTAL

      --------||--------
     |        C0        |
  ---|                  |---
     |   R1   C1   L1   |
      --/\/\--||--UUUU--

Typical Parameter Values (Q=18,000)

      200kHz    2MHz     30MHz(3OT) 90MHz(5OT)
R1     2k       100R        20R        40R
L1     27H     0.52H       11mH        6mH
C1    24fF      12fF      2.6fF      0.5fF
C0     9pF       4pF        6pF        4pF

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PRBS

patterns used by HP3781A/3782A Pattern Generator & Error Detector

 2^9-1  to CCITT Rec. V.52   (x^9 + x^5 + x^0)
 2^15-1 to CCITT Rec. O.151  (x^15 + (NOT x^14) + x^0)
 2^23-1 to CCITT Rec. O.151  (x^23 + (NOT x^18) + x^0)

ref. 3781A, 3782A Operating Manual