Controllable multi-phase ring oscillators with variable current sources and capacitances
AssigneeNCR Corporation
InventorRicky F. Bitting
Life of this patent
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Abstract
An electrically controlled oscillator circuit having multi-phase outputs with programmable frequency. The circuit includes a ring oscillator having a plurality of inverting stages. Each stage has an output which is connected to a switch that can be programmed to select one of a plurality of capacitors with different values to change the frequency range of the oscillator. Controlled current is fed to the stages to vary the frequency of the oscillator within a selected frequency range. Using capacitors to change the frequency range of the oscillator reduces variations of the oscillator output frequency.
Claims13
An electrically controlled oscillator circuit comprising:
- a ring oscillator having a plurality of stages, each stage having an input terminal and an output terminal, and producing a signal having a preselected frequency;
- a plurality of capacitor means having electrically programmable capacitance values, each of said capacitor means being electrically coupled to respective ones of said output terminals of said plurality of oscillator stages;
- and
- means for selecting the programmable values of said plurality of capacitor means for setting said output signal frequencies of said stages.
An electrically programmable oscillator circuit comprising:
- a ring oscillator having a plurality of inverters with an input and an output terminal, each inverter being operative to provide a preselected frequency, said inverters, being connected in a series circuit arrangement with an output terminal of each inverter being coupled to an input terminal of a next inverter in the series;
- means for providing a variable bias current to said plurality of inverters such that the preselected frequency of each inverter varies within a predetermined range as a function of the bias current;
- means for providing a plurality of different frequency programming signals;
- and
- a plurality of variable capacitance stages respectively connected to the output terminals of said inverters, said inverters being responsive to the different frequency programming signals for selecting a capacitance value to set the predetermined range in which the frequency of each inverter varies.
An electrically controlled oscillating circuit comprising:
- a ring oscillator having a plurality of inverting stages, each of said stages having an input terminal and an output terminal, wherein said input terminals being electrically connected to a respective output terminal of another of said stages for establishing a series circuit arrangement of said stages;
- means for providing a varying voltage level;
- a plurality of current sources respectively connected to said providing means and respectively connected to said stages, said current sources having means for feeding current to said stages and for varying the magnitude of current to said stages in accordance with the level of said varying voltage, said inverting stages being responsive to said magnitude of current for setting an oscillation frequency of said ring oscillator;
- and
- a second-ring oscillator having a plurality of stages with an input terminal and an output terminal, each stage providing a preselected oscillation frequency signal;
- a plurality of capacitors having electrically programmable capacitance values, said capacitors being electrically coupled to respective ones of the output terminals of the plurality of stages of said second ring oscillator, the programmable values of said plurality of capacitors controlling said preselected oscillation frequency;
- means connected to said first ring oscillator and said second ring oscillator for providing a signal for selecting either the first ring oscillator or the second ring oscillator;
- and
- means responsive to said signal for enabling the output of the selected ring oscillator and for disabling the output of the other of the ring oscillators.
A programmable ring oscillator comprising a plurality of serially coupled oscillator stages, each of said stages including a plurality of capacitors selectively connectable in circuit with said stages for establishing a preselected oscillation frequency band for said oscillator, and each of said stages further including a controllable current source for establishing a selected current for setting a selected oscillation frequency within said frequency band.
Dependencies are inferred from the claim text.