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EMITTER-COUPLED LOGICINEL4207 - Spring 2012
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Figure 15.25 The basic element of ECL is the differential pair. Here, VR is a reference voltage.
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R
Q1 Q2
IEE
-VEE
vIN VREF
vC1 Q3
IE3
vO
SIMPLIFIED ECL INVERTER
Example: Select R so that VL = -1.5V. Use IEE = 0.1mA.
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R
Q1 Q2
-VEE
vIN VREF
vC1 Q3
IE3
vO
REEIREE
R3
-VEE2
ECL WITH RESISTOR BIASING
Example: Find R and R3 if VEE = VEE2 = −5.2V, VL = −1.3V, IEE = 300μA and IEE2 = 100μA.
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R
Q1 Q2
-VEE
vIN VREF
vC1 Q3
IE3
vO
REEIREE
R3
R4
Example: Use the above circuit design an ECL gate for which VH = −1.7V and VL = −2.3V . The average power dissipation should be less that 2mW. The supply voltage is −5.2V . Neglect the base currents.
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Figure E15.12
Find VR if vD1 = vD2 = vBE = 0.75V. Neglect iB.
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Figure 15.26 Basic circuit of the ECL 10K logic-gate family.
tp ≈ 1ns, the time it takes light to travel 1 foot.
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For previous circuit, find IE through RE if A and B are left open. Also find vC,QR and vCA,B. Use VR = -1.32V, VBE=0.75V and a very large β.
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Figure 15.27 The proper way to connect high-speed logic gates such as ECL. Properly terminating the transmission line connecting the two gates eliminates the “ringing” that would otherwise corrupt the logic signals. (See Section 15.4.6.)
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Figure 15.28 Simplified version of the ECL gate for the purpose of finding transfer characteristics.
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Figure 15.28 Simplified version of the ECL gate for the purpose of finding transfer characteristics.
Find VOL and VOH (neglect iC of QR) if β=100. Then find NMH and NML if VIL and VIH are defined as the conditions for which IE, QR/IE, QA = 99 and vice-versa.
For VOH take into account base current and variations in vBE. Assume that at iC = 1mA, vBE = 0.75V.
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Figure 15.30 Circuit for determining VOH.
VOH = -0.88V. Take into account base current and variations in vBE. Assume that at iC = 1mA, vBE = 0.75V.
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Figure 15.31 15.28
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Figure 15.32
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Figure 15.33 Equivalent circuit for determining the temperature coefficient of the reference voltage VR.
δ = -2mV/℃
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Figure 15.36 The wired-OR capability of ECL.
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Figure P15.30
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Figure P15.39
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