Zero phase startup for a tank type voltage controlled oscillator
AssigneeTexas Instruments Incorporated
InventorMichael H. Haight
Life of this patent
Estimating the term…
Abstract
A self contained circuit to enable a tank type (coil/capacitor) voltage controlled oscillator to start up and free run from a known state. The circuit allows the oscillator to be stopped to within two periods by invoking its only input logic signal and also restarted with no adverse effects on its free running operation. It includes three current mirrors, one which sets the current for the other two mirrors and of the final two, one actively sets a bias on a coil (stops oscillation) while the other makes up for the lack of coil bias by providing an equivalent amount current influx to the oscillator in the free running condition.
Claims16
An oscillator system comprising:
- (a) a tank type oscillator having a coil and a capacitor;
- (b) means to control the current in said coil comprising:
- first means coupled to one end of said coil to provide a substantially constant normal DC current through said coil providing a substantially constant normal DC voltage at said end of said coil;
- second means coupled to the other end of said coil to provide a substantially constant normal DC voltage at said other end of said coil;
- and
- means responsive to a predetermined condition to reciprocatingly operate said first and second means.
Dependencies are inferred from the claim text.