It is pin-for-pin compatible with the CDB, but exhibits a much lower on-state resistance. In addition, the on-state resistance is relatively constant over the full signal-input range. The CDB consists of four bilateral switches, each with independent controls. Both the p and the n devices in a given switch are biased on or off simultaneously by the control signal. As shown in Figure 1, the well of the n-channel device on each switch is tied to either the input when the switch is on or to VSS when the switch is off. This configuration eliminates the variation of the switch-transistor threshold voltage with input signal and, thus, keeps the on-state resistance low over the full operating-signal range.
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CD can be used in multiplexing of analog or digital signals. The switches inside this IC have very low internal resistance. Therefore, it can be used in audio applications and in isolating signals. How to use it? The working principle of this quad bilateral switch is very easy. The CD IC consists of four switches. It can switch analog signals through digital control. An analog signal is applied at the input of the switch. If a HIGH or 1 value is fed into the control input, the analog signal will be passed from input to the output of a switch.
The internal structure of this IC is shown in the figure below. As it is a bilateral switch, therefore it can operate in both directions forward and reverse. Each switch has two pins which can be used as both input and output for switching voltages. Pin 14 is connected to the positive terminal of voltage supply and pin 7 is connected to the ground of the circuit. When the control input is HIGH or 1, the terminals of the switch have low impedance between them, and they are said to be in ON condition.
Truth Table Working Output The truth table indicating the effect on output by changing inputs is shown in the table given below.
CD4066 CMOS Quad Bilateral Switches IC