Frequency doubling circuit
AssigneeNational Semiconductor Corporation
InventorsDavid K. Long, Robert W. Miller
Life of this patent
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Abstract
A frequency doubler circuit uses a single capacitor which is initially charged. A pair of switches is sequentially actuated so that each switch acts to first discharge the capacitor and then charge it in the opposite polarity. The switches are sequentially actuated from a differential input amplifier. Thus each input cycle will actuate both switches so as to discharge and charge the capacitor twice. Output logic senses the capacitor cycling and produces two output pulses for each input cycle.
Claims5
A frequency doubling circuit having an input for accommodating an input signal, including driver means responsive to said input signal for operating said circuit and means for coupling said circuit to first and second power supply terminals, said circuit comprising:
- a capacitor having first and second terminals;
- a first switching transistor having a collector coupled to said first capacitor terminal, an emitter coupled to said first power supply terminal, and a base coupled to said driver means;
- a second switching transistor having an emitter coupled to said second capacitor terminal, a collector coupled to said second power supply terminal and a base coupled to said base of said first switching transistors;
- a third switching transistor having a collector coupled to said second capacitor terminal, an emitter coupled to said first power supply terminal and a base coupled to said driver means;
- a fourth switching transistor having an emitter coupled to said first capacitor terminal, a collector coupled to said second power supply terminal, and a base coupled to said base of said third switching transistor;
- resistive means coupling each terminal of said capacitor to said second power supply terminal;
- means in said driver means for driving said fist and second switching transistor bases in phase opposition to said third and fourth switching transistor bases in response to said input signal;
- and
- output logic means coupled to said terminals of said capacitors whereby two output pulses are produced for each cycle of said input signal.
Dependencies are inferred from the claim text.