Oscillator circuits
AssigneeRCA Corporation
InventorsAbel Ching Nam Sheng, Max Edward Malchow
Life of this patent
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Abstract
A micropower, latch-up free, relaxation oscillator includes a switch such as a programmable unijunction transistor or a silicon-controlled-switch. The switch is coupled at its gate electrode via an emitter-follower circuit of low output impedance, to a source of reference potential provided by a relatively high resistance resistive voltage divider. The condition of the switch, whether conducting or not, is controlled by a resistor-capacitor timing circuit. When the capacitor charges to a given level, it causes the switch to conduct and to act as a discharge circuit for the capacitor. When the capacitor discharges to a second level, the switch goes off and the cycle then repeats.
Claims13
A relaxation oscillator comprising:
- first and second terminals across which an operating voltage may be applied;
- resistive means;
- a solid-state switch having a control electrode receptive of a control voltage for operating said switch, and first and second electrodes defining a main current carrying path enabled by turn-on of said switch, said second electrode being connected to said second terminal through said resistive means;
- a source exhibiting a given source impedance for providing a reference voltage;
- impedance transformation means coupled between said source and said control electrode for applying said reference voltage to said control electrode at a substantially lower impedance level, relative to said control electrode, than exhibited by said source;
- a charging circuit connected between said two terminals, said circuit including a charge storage element for developing a voltage thereacross which increases as a function of time;
- a discharging circuit for said storage element comprising means for applying the voltage developed thereacross between said first electrode and said second terminal, said voltage causing said switch to turn on when it reaches a first value, and said switch turning off when said voltage reduces to a second value;
- and
- a regenerative feedback circuit comprising a capacitor coupled between said first and second electrodes for supplying current to said resistive means in a sense to turn off said solid-state switch, upon discharge of said charge storage element.
An oscillator comprising, in combination:
- first and second operating voltage terminals;
- a switch having first and second electrodes defining a current carrying path and a control electrode for controlling the conduction through said path;
- load means connecting said second electrode of said switch to said second terminal;
- a voltage divider connected between said terminals for producing a reference voltage at the output terminal thereof;
- an emitter-follower comprising a transistor having base, emitter and collector electrodes and an emitter load, connected at its base electrode to said output terminal of said voltage divider, at its collector electrode to said first terminal and at its emitter electrode through said emitter load to said second terminal, said emitter electrode being coupled also to said control electrode;
- a charging circuit comprising a charge storage means and impedance means connected in series between said first and second terminals, said circuit including an output terminal at which an output voltage is produced in a response to charging of said charge storage means;
- a discharge circuit for said storage means comprising the current carrying path of said switch, said output terminal of said charging circuit being connected to said first electrode of said switch;
- and
- a regenerative feedback connection between said first and second electrodes of said switch for applying a signal to said second electrode in a sense to turn off said switch in response to discharge of said charge storage means.
Dependencies are inferred from the claim text.