Curtis CEM3340 Voltage Controlled Oscillator (VCO)
The legendary monolithic precision analog oscillator IC designed by Doug Curtis, powering the Roland Jupiter-6, SH-101, Memorymoog, and Prophet-5 Rev 3.
# Mathematical Formula & Architecture
Logic Specification1V/Octave exponential converter with simultaneous buffered Triangle, Sawtooth, and Variable Pulse outputs.
CEM3340 Pinout Configuration Highlights:
Pin 3: Negative Supply (-15V)
Pin 4: Temperature Compensated 1V/Octave CV Input
Pin 6: Hard Sync Input (Resets ramp capacitor on rising edge)
Pin 8: Triangle Wave Output
Pin 9: Variable Pulse / Square Wave Output
Pin 10: Sawtooth Wave Output
Pin 16: Positive Supply (+15V)# Deep Technical Analysis & Historical Context
Designed by Curtis Electromusic Specialties in 1979, the CEM3340 solved the notorious tuning instability of early discrete analog synthesizers. Before the 3340, analog synths drifted wildly out of tune as ambient studio temperatures changed because transistor base-emitter voltage varies by -2mV/°C. Doug Curtis incorporated an on-chip temperature-compensating heating circuit and precision exponential multiplier onto a single silicon die. The CEM3340 provides pristine 1V/Octave pitch tracking over more than 10 octaves, exceptionally low frequency drift (under 1 cent over 20°C), and instantaneous hard/soft oscillator synchronization capabilities.
Common Studio Pitfall & Hardware Hazard
Replacing a defective vintage CEM3340 with an uncalibrated modern clone without trimming the high-frequency tracking trim pot will result in flat octaves above C5.
# Hardware Synthesizers Using This Technology
Click any synthesizer below to explore its specific memory protect routine, factory soundbanks, and Web MIDI SysEx cloud backup engine:
# Frequently Asked Engineering Questions
Which famous synths use the CEM3340?
Sequential Circuits Prophet-5 (Rev 3), Roland Jupiter-6, Roland SH-101, Roland MC-202, Memorymoog, Oberheim OB-Xa/OB-8, and the modern Behringer Crave/Pro-1.
Related Engineering Concepts
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