Improved Clamp for Differential VCO and Single-Shot
Original Publication Date: 1988-Jan-01
Included in the Prior Art Database: 2005-Feb-14
A hysteresis is implemented in the clamps of a differential Multivibrator circuit. The hysteresis assures faster transition time between states during oscillation, and, therefore, a more predictable output frequency or pulse width. The figure shows an Emitter Coupled Multivibrator, commonly used as a Voltage Controlled Oscillator (VCO), with the hysteresis implemented. The significant feature of this invention is the way the bases of clamp transistors 1 and 4 are connected to taps in resistors 7 and 8. In State 1 of the oscillation cycle, transistors 9 and 11 are ON, and transistors 6 and 12 are OFF. A current exists in resistor 7, so the base of transistor 1 is 0.1 volt more negative than the base of transistor 3. This 0.1 volt is the hysteresis of this invention.