emitter-coupled logicece.uprm.edu/~mtoledo/web/4207/s2014/ecl.pdf · r q 1 q 2-v ee v in v ref v c1...
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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.
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.
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.
Figure 15.26 Basic circuit of the ECL 10K logic-gate family.
tp ≈ 1ns, the time it takes light to travel 1 foot.
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.
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.)
Figure 15.28 Simplified version of the ECL gate for the purpose of finding transfer characteristics.
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.
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.
Figure 15.33 Equivalent circuit for determining the temperature coefficient of the reference voltage VR.
δ = -2mV/℃
Name: INEL4207 Digital Electronics - A2
Student #: Sec.: December 21, 2010
This exam has 3 problems. Each problem counts for 1/3 of the exam grade.
1. For the ECL inverter shown in the following sketch, the high voltage level is VH = −1.7V andthe average power dissipated when the input is high 50% of the time is P = 5mW . Determinethe source’s current IEE, the low voltage level VL, the reference voltage level VREF and thevalue of resistance R3.
-5.2V-3.3V
VREFvin
2k�
2k�
IEE
Q1 Q2
Q3
voutR3
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