Dual input voltage controlled oscillator with compensated bang/bang frequency

Claim 2

A two input voltage controlled oscillator, the first input comprising an analog signal for adjusting the voltage controlled oscillator's output frequency around a predefined center output frequency and the second input comprising a digital signal which switches the voltage controlled oscillator's center output frequency between two bang/bang frequencies, wherein the time difference between the periods of the two bang/bang frequencies, divided by the period defined by the voltage controlled oscillator's operating frequency, is a constant fraction which is independent of the voltage controlled oscillator's supply voltage variations, its operating temperature variations, and its process variations.

Claim 3

The two input voltage controlled oscillator of claim 1, the oscillator further comprising: a plurality of variable delay cells, each delay cell having a first input and a first output, the first output of each variable delay cell coupled to a first input of a succeeding variable delay cell, the plurality of variable delay cells thereby forming a ring, an odd number of variable delay cells having their first output inverted before the first output is coupled to a succeeding variable delay cell, each variable delay cell further comprising an analog signal input for receiving the analog signal and a bang/bang signal input for receiving a bang/bang signal; and a plurality of bang/bang modulators, each bang/bang modulator providing the bang/bang signal to a respective variable delay cell, each bang/bang modulator having a disable signal input for receiving a disable signal and a digital signal input for receiving the first digital signal.

Claim 4

The voltage controlled oscillator of claim 2, wherein the total delay of the ring of variable delay cells is determined by a modulation current, the modulation current having a first predetermined direct current component and a second bang/bang current component provided by the bang/bang signal from the bang/bang modulators.

Claim 5

The voltage controlled oscillator of claim 3, wherein the ratio of the bang/bang current component and the direct current component of the modulation current is defined by a ratio of resistors in the variable delay cells and the bang/bang modulators.

Claim 6

In a voltage controlled oscillator comprised of a plurality of variable delay cells coupled together in a ring configuration, the oscillator having a predetermined center operating frequency and a bang/bang signal input for shifting the center operating frequency up and down by a predefined bang/bang frequency, a method for controlling the bang/bang frequency comprising the steps of: controlling the delay time through the variable delay cells by means of a modulation current; and generating the modulation current from a combination of a direct current and a bang/bang modulation current, the ratio of the direct current and the bang/bang modulation current being determined by a ratio of resistors.

Claim 7

In a voltage controlled oscillator comprised of a plurality of variable delay cells coupled together in a ring configuration, the oscillator having a predetermined center operating frequency and a bang/bang signal input for shifting the center operating frequency up and down by a predefined bang/bang frequency, a method for controlling the bang/bang frequency comprising the steps of: controlling the delay time through the variable delay cells by means of a modulation current; and generating the modulation current from a combination of a direct current and a bang/bang modulation current, the ratio of the direct current and the bang/bang modulation current being determined by a ratio of resistors.