Tunable oscillators and signal generation methods
OwnerSassan Tabatabaei, Andre Ivanovinventors
Life of this patent
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Abstract
A time to digital converter (TDC) has a pair of digital oscillators. The periods of the oscillators differ by TΔ. The oscillators are triggered by START and STOP pulses. A counter counts a number of pulses until reference points on the signals output by the oscillators coincide. Measurements may be made using a dual resolution method. Intrinsic jitter of the TDC can be determined by comparing sets of measurements in which the switch in resolutions is made at different points.
Claims21
A frequency tunable digital ring oscillator comprising a closed signal path defined at least in part by a plurality of series connected delay elements each having an input and an output the delay elements comprising at least one digitally controllable delay element, the digitally controllable delay element comprising a gate connected in series with the signal path and a tri-state device having an input connected to an output of the gate and a control connection connected to a control device.
A digital timing circuit for generating first and second signals respectively having first and second periods which are different from one another, the timing circuit comprising:
- a first ring oscillator triggered by a first control signal and generating the first signal;
- a second ring oscillator triggered by a second control signal and generating the second signal;
- at least one of the oscillators comprising a plurality of controllable delay elements, the delay elements, when activated altering a period of the signal generated by the at least one of the oscillators;
- a coincidence detector connected to generate a coincidence signal when a reference point in the first signal has a known time relationship to a corresponding reference point on the second signal;
- a counter connected to count a number (N) of cycles of the first oscillator between the first control signal and the coincidence signal;
- and,
- a resolution adjustment circuit connected to generate the first and second control signals at times separated by a known interval, compare the number N to a threshold and, if N is not at least equal to the threshold, alter the period of the at least one of the oscillators by activating or deactivating one or more of the digitally controllable delay elements.
A method for producing first and second digital signals having first and second periods, the method comprising:
- a) providing a pair of digital oscillators which, when started, respectively produce first and second signals;
- b) starting the first oscillator and starting the second oscillator a time period Td after starting the first oscillator;
- c) counting a number N of features of the first signal until a reference point on the first signal coincides with a corresponding reference point on the second signal;
- d) if N is not at least equal to a threshold value altering the period of at least one of the oscillators and repeating operations (b) and (c) until N is at least equal to the threshold value.
A frequency tunable digital ring oscillator comprising a closed signal path defined at least in part by a plurality of series-connected delay elements each having an input and an output the delay elements comprising at least one digitally controllable delay element, the digitally controllable delay element comprising a gate connected in series with the signal path and a capacitor connected in series between the output of the gate and a digital switch.
Dependencies are inferred from the claim text.