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XNOR gates are represented in most TTL and CMOS IC families. The standard 4000 series CMOS IC is the 4077, and the TTL IC is the 74266 (although an open-collector implementation). Both include four independent, two-input, XNOR gates. The (now obsolete) 74S135 implemented four two-input XOR/XNOR gates or two three-input XNOR gates.
In the CMOS implementation on the right, the function of the pull-up resistor is implemented by the two p-type transistors in series on the top. The physical layout of a CMOS NOR. In CMOS, NOR gates are less efficient than NAND gates. This is due to the faster charge mobility in n-MOSFETs compared to p-MOSFETs, so that the parallel connection ...
The following is a list of CMOS 4000-series digital logic integrated circuits.In 1968, the original 4000-series was introduced by RCA.Although more recent parts are considerably faster, the 4000 devices operate over a wide power supply range (3V to 18V recommended range for "B" series) and are well suited to unregulated battery powered applications and interfacing with sensitive analogue ...
As an example, here is a NOR gate implemented in schematic NMOS. If either input A or input B is high (logic 1, = True), the respective MOS transistor acts as a very low resistance between the output and the negative supply, forcing the output to be low (logic 0, = False).
Some manufacturers released some 4000-series equivalent CMOS circuits with a 74 prefix, for example, the 74HC4066 [2] was a replacement for the 4066 with slightly different electrical characteristics (different power-supply voltage ratings, higher frequency capabilities, lower "on" resistances in analog switches, etc.).
7400 series parts were constructed using bipolar junction transistors (BJT), forming what is referred to as transistor–transistor logic or TTL. Newer series, more or less compatible in function and logic level with the original parts, use CMOS technology or a combination of the two ( BiCMOS ).
The picture represents a typical ECL circuit diagram based on Motorola's MECL. In this schematic, transistor T5′ represents the output transistor of a previous ECL gate that provides a logic signal to input transistor T1 of an OR/NOR gate whose other input is at T2 and has outputs Y and Y.
Examples of digital comparator include the CMOS 4063 and 4585 and the TTL 7485 and 74682. An XNOR gate is a basic comparator, because its output is "1" only if its two input bits are equal. The analog equivalent of digital comparator is the voltage comparator .