The CD4066B is a widely used CMOS quad bilateral switch designed for efficient transmission of both analog and digital signals in electronic circuits. Its ability to provide four independent switching channels within a single device makes it a flexible solution for signal control and routin. This article will discuss the CD4066B overview, pin configuration, variant models, functional operation, specifications, features, working principles, and more.

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CD4066B Overview

The CD4066B is a CMOS quad bilateral switch designed to transmit both analog and digital signals. It contains four independent switches within a single IC, each controlled by its own control input. When the control signal is HIGH, the switch turns ON and allows the signal to pass; when LOW, the switch turns OFF and blocks the signal. It is pin-compatible with similar devices but offers lower ON-state resistance, which helps maintain signal quality.

Each switch uses complementary p-channel and n-channel MOS transistors that operate together, allowing signals to pass in both directions. The internal design keeps the ON resistance relatively stable across the full input signal range. This ensures consistent performance and reduces signal distortion during operation.

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CD4066B CAD Models

CD4066B Pinout Details

CD4066B Variant Models

Alternatives & Equivalent Model

• CD4016

• SN74HC4066

• HEF4066B

• MC14066B

• BU4066BC

Functional Block Diagram

The functional block diagram of the CD4066B shows how each switch is controlled and how signals pass through the device. The control input (VC) is fed into internal inverter stages, which generate complementary signals. These signals drive both the p-channel and n-channel MOS transistors inside the switch. When the control input is HIGH, both transistors turn ON, creating a low-resistance path between the input (Vis) and output (Vos). When the control input is LOW, both transistors turn OFF, isolating the signal path.

The central part of the diagram represents the bilateral switch. It uses parallel p-channel and n-channel MOSFETs to allow signals to pass in either direction. This structure ensures that the switch can handle analog signals across a wide voltage range while maintaining relatively constant ON resistance.

The CMOS protection network on the right side protects the device from voltage spikes and electrostatic discharge. It uses diodes connected to VDD and VSS to clamp excessive voltages, helping improve reliability and prevent damage to the internal circuitry.

CD4066B Technical Specifications

CD4066B Broad Features

Wide Signal Voltage Handling

The CD4066B supports up to 15 V digital signals or ±7.5 V peak-to-peak analog signals. This allows it to handle both low-level and relatively higher voltage signals within the same device. Because of this wide range, the switch can maintain stable operation across different signal amplitudes without distortion or clipping.

Low ON-State Resistance

The device offers a typical ON resistance of around 125 Ω at 15 V operation. This low resistance helps reduce signal loss when the switch is ON, allowing signals to pass through with minimal attenuation and preserving overall signal integrity.

Matched ON Resistance Across Channels

The ON-state resistance is matched within about 5 Ω across the full signal input range. This consistency ensures uniform behavior between all four switches, which is important in circuits requiring balanced or synchronized signal paths.

Flat Resistance Over Signal Range

The ON resistance remains relatively constant across the entire peak-to-peak signal range. This means the switch introduces minimal variation or distortion as the signal level changes, helping maintain linear signal transmission.

High ON/OFF Output Voltage Ratio

The CD4066B provides a high ON/OFF output voltage ratio, typically around 80 dB. This ensures strong signal transmission when ON and effective isolation when OFF, reducing unwanted signal leakage and improving switching performance.

High Linearity Performance

With less than 0.5% distortion under typical conditions, the device maintains high linearity. This ensures that the output signal closely matches the input signal without significant waveform distortion, especially important for accurate signal handling.

Extremely Low OFF-State Leakage

The switch exhibits very low leakage current when in the OFF state, typically around 10 pA. This results in high effective OFF resistance and ensures that unwanted signals do not pass through when the switch is disabled.

High Control Input Impedance

The control input has extremely high impedance, typically around 10¹² Ω. This isolates the control circuit from the signal path, preventing interference and ensuring that control signals do not affect signal transmission.

Low Crosstalk Between Switches

The device provides low crosstalk between its internal switches, typically around -50 dB. This minimizes interference between channels, ensuring that signals remain independent and do not affect each other.

Reduced Signal Transients

Matched control-input to signal-output capacitance helps reduce unwanted signal transients during switching. This leads to smoother transitions and more stable output signals when switching states.

Fast Frequency Response

The CD4066B can operate at frequencies up to around 40 MHz. This allows it to handle relatively high-speed signals without significant degradation, making it suitable for fast signal switching applications.

Low Quiescent Current

The device is tested for low quiescent current at 20 V, ensuring minimal power consumption when idle. This is a key advantage in low-power electronic designs.

Flexible Operating Voltage Options

The CD4066B supports multiple standard voltage levels, including 5 V, 10 V, and 15 V. This flexibility allows it to be easily integrated into various circuit designs with different power supply requirements.

CD4066B Working in Circuit

How the CD4066B is used as an analog signal switch controlled by a logic signal? The input signal (Vin) is first buffered by an operational amplifier (LF353), which ensures the signal is stable and has low output impedance before reaching the switch. This helps maintain signal accuracy and prevents loading effects that could distort the input.

The CD4066B acts as the main switching element. The control input (CTRL) determines whether the internal switch is ON or OFF. When the control signal is HIGH, the switch closes and allows the buffered signal to pass through the OUT/IN pins. When the control signal is LOW, the switch opens and blocks the signal path, effectively disconnecting the input from the rest of the circuit.

A capacitor (C1) is placed after the switch to filter or smooth the signal. It can help reduce noise or stabilize the signal during switching transitions. The output stage uses another operational amplifier (LF353), configured as a buffer, to isolate the load and provide a clean, stable output (Vout). The circuit demonstrates how the CD4066B can control the flow of analog signals using a digital control signal, while maintaining signal integrity through buffering and filtering stages.

CD4066B Applications

• Audio signal switching

• Analog signal multiplexing

• Sample-and-hold circuits

• Data acquisition systems

• Signal routing in communication systems

• Waveform gating circuits

• Analog filtering and signal conditioning

• Digital-to-analog signal switching

• Test and measurement equipment

• Microcontroller-controlled signal switching

CD4066B Mechanical Dimensions

Manufacturer

Texas Instruments (TI), the manufacturer of the CD4066B, is a global semiconductor company known for its strong capabilities in analog and embedded processing technologies. TI operates advanced wafer fabrication and assembly facilities, enabling high-volume, high-reliability production of CMOS devices like the CD4066B. The company focuses on precision analog performance, long product life cycles, and consistent quality. TI also provides extensive technical documentation, design tools, and application support, helping engineers integrate its products efficiently into various electronic systems.