The basic gate circuit of the ECL 10K family is shown in Fig. 15.26. The circuit consists of three parts. The network composed of Q1, D1, D2, R1, R2, and R3 generates a reference voltage VR whose value at room temperature is –1.32 V.
What is noise margin of ECL?
DC noise margins in ECL 10K are much less than in CMOS and TTL, only 0.155 V in the LOW state and 0.125 V in the HIGH state. However, ECL gates do not need as much noise margin as these families.
What are the advantages of ECL?
Following points summarize ECL advantages over TTL and CMOS: ➨It has fanout of 25 which is better than TTL and less then CMOS. ➨It has average propagation delay time ( 1 to 4 ns ) better compare to both TTL and CMOS. Hence it is known as fastest logic family.
Why ECL has least propagation delay?
Reason (R): ECL prevents adverse effects of diffusion capacitance as it does not operate fully saturated or cut off.
What are the characteristics of ECL gates?
In ECL, the transistors are never in saturation, the input/output voltages have a small swing (0.8 V), the input impedance is high and the output impedance is low. As a result, the transistors change states quickly, gate delays are low, and the fanout capability is high.
What is TTL and ECL?
TTL (Transistor Transistor Logic) IC technology uses bipolar transistor as principal circuit element. ECL (Emitter Coupled Logic) IC technology uses bipolar transistors configured as differential amplifier.
Why do we use DTL?
Operation of DTL: In an integrated circuit version of the gate, two diodes replace R3 to prevent any base current when one or more inputs are at low logic level. Alternatively to increase fan-out of the gate an additional transistor and diode may be used.
Which logic family is the fastest *?
Emitter-coupled-logic
Emitter-coupled-logic (ECL) is a BJT logic family that is generally considered the fastest logic available.
Which TTL family is fastest?
Emitter-coupled-logic (ECL): Emitter-coupled-logic (ECL) is a BJT logic family that is generally considered the fastest logic available.
What is fan-out in IC?
Fan-out is a term that defines the maximum number of digital inputs that the output of a single logic gate can feed. Most transistor-transistor logic ( TTL ) gates can feed up to 10 other digital gates or devices. Thus, a typical TTL gate has a fan-out of 10.
What are the advantages and disadvantages of ECL?
Since the BJTs of ECL gates operate in the active region, they have the highest speed among all logic families. ECL gates produce complementary outputs (OR-NOR). Current switching spikes are not present in power supply leads.
What is the power dissipation of ECL 100K series?
The ECL 100K series features gate delays on the order of 0.75 ns and dissipates about 40 mW/gate, for a delay–power product of 30 pJ. Although its power dissipation is relatively high, the 100K series provides the shortest available gate delay in small- and medium-scale integrated circuit packages.
What are the advantages of ECL over CMOS and TTL?
Thus, unlike CMOS (and TTL), no supply current spikes occur in ECL, eliminating an important source of noise in digital circuits. This is a definite advantage, especially since ECL is usually designed to operate with small signal swings and has correspondingly low noise margins.
How to avoid saturation in ECL?
Saturation in ECL is avoided by using the BJT differential pair as a current switch.5The BJT differential pair was studied in Chapter 9, and we urge the reader to review the introduction given in Section 9.2 before proceeding with the study of ECL. 15.4.1 The Basic Principle
What is the basic element of ECL?
Figure 15.25The basic element of ECL is the differ- ential pair. Here,V R is a reference voltage. 4Althoughhigherspeedsofoperationcanbeobtainedwithgalliumarsenide(GaAs)circuits,thelatterare not available as off-the-shelf components for conventional digital system design.
