Overview

The CD4069UB (CD4069) is a monolithic CMOS integrated circuit containing six independent unbuffered inverting circuits. Unlike "B-series" buffered inverters (such as the CD4049B or 74HC04) which cascade three internal inverter stages per gate to maximize digital switching gain, the CD4069UB uses a single complementary MOSFET pair per inverter.

Because it lacks internal cascaded stages, the CD4069UB features lower open-loop voltage gain ($A_v \approx 20\text{ to }30\text{ dB}$ at $V_{DD} = 10\text{V}$) and minimal phase shift across its operating range. This makes the CD4069UB the industry-standard CMOS chip for RC multi-vibrators, crystal oscillators, pulse generators, and linear analog audio circuits (such as synthesizer filters, preamplifiers, and classic guitar overdrive/fuzz distortion pedals like the Craig Anderton Tube Sound Fuzz and Way Huge Red Llama).

Quick reference

Pinout (DIP-14 Package)

             ┌───┴───┐
          1A 1│ 1   14│ VDD
          1Y 2│       │13 6A
          2A 3│       │12 6Y
          2Y 4│CD4069UB 11 5A
          3A 5│       │10 5Y
          3Y 6│       │9  4A
         VSS 7│       │8  4Y
             └───────┘

Function Table

Specifications

Typical Applications

1. Self-Biased Linear Audio Amplifier / Distortion Stage

Connecting a large feedback resistor ($1\text{ M}\Omega \dots 10\text{ M}\Omega$) from output to input biases the inverter into its linear region at $V_{DD} / 2$:

               ┌─────[ R_f = 1MΩ ]─────┐
               │                       │
 Audio In ──[ C_in ]───► [Pin 1: 1A]    │
                         CD4069UB       ├────[ C_out ]───► Amplified Audio Out
                         [Pin 2: 1Y] ───┘

When driven past its linear region, the single-stage MOSFET pair produces gradual, tube-like soft saturation rather than harsh digital rail clipping.

2. High-Stability 32.768 kHz / Megahertz Crystal Oscillator

             ┌─────[ R1 = 10MΩ ]─────┐
             │                       │
             ├───[ XTAL ]───┬────────┤
             │              │        │
      [Pin 1: 1A]     [Pin 2: 1Y]    └──► [Pin 3: 2A] (Buffer) ──► Square Wave Out
          │                 │
       [ C1 = 22pF ]     [ C2 = 22pF ]
          │                 │
         GND               GND

Common mistakes

• Substituting a buffered inverter (CD4049B / 74HC04) into oscillator or linear audio circuits: Buffered ICs have extreme voltage gain ($>1000$) and three internal stages; using them in place of unbuffered CD4069UB causes severe high-frequency self-oscillation and parasitic RF noise.
• Leaving unused inverter inputs open: Unconnected high-impedance inputs float to midpoint voltages, turning both internal P- and N-channel MOSFETs simultaneously ON and drawing excessive supply current. Tie unused inputs directly to VDD or VSS.

Notes

• Suffix Identification: Always verify the UB suffix (CD4069UB, HEF4069UB, TC4069UBP). Standard "B" series equivalents without the UB designation have buffered outputs.