Controlled feedback path voltage controlled oscillator
AssigneeMotorola, Inc.
InventorsLawrence M. Ecklund, Charles J. Marik
Life of this patent
Estimating the term…
Abstract
A voltage controlled oscillator having a first feedback path and a second feedback path. The first feedback path may include a phase shift unit (13) as necessary to compensate for an inherent phase shift provided by the resonant circuit (11) used therewith. The second feedback path includes a steering network (17) that responds to an external control signal to cause the output signal to be selectively in either of two phase relations with respect to the incoming signal. The control signal can also control the magnitude of the output signal. By control of the phase relationship and the magnitude, the steering network (17) can effectively control the output frequency of the resonant circuit (11).
Claims16
A voltage controlled oscillator comprising:
- (a) resonant circuit means for resonating at a resonant frequency and having an input for receiving a feedback signal and an output for providing an oscillator output signal;
- (b) first feedback means for receiving said oscillator output signal and for providing a first feedback signal as a function of said oscillator output signal, said first feedback signal having a substantially fixed predetermined phase relationship with respect to said oscillator output signal;
- (c) second feedback means for receiving both said oscillator output signal and a control signal and for providing a second feedback signal as a function of said oscillator output signal and said control signal, such that said control signal can control when said second feedback signal has a first predetermined phase relationship with respect to said oscillator output signal and when said second feedback signal has a second and different predetermined phase relationship with respect to said oscillator output signal, wherein said second feedback means includes phase shift means for receiving said oscillator output signal and for phase shifting said oscillator output signal 90 degrees, and wherein said phase shift means includes:
- (d) first phase lead means for providing a phase lead that decreases with increasing frequency;
- and
- (e) second phase lead means for providing a phase lead that increases with increasing frequency;
- (f) summing means for receiving and combining said first feedback signal and said second feedback signal, and for providing said combined feedback signals to said input of said resonant circuit means, such that said oscillator output signal has a frequency that can be controlled, at least in part, by said control signal.
Dependencies are inferred from the claim text.