Method and apparatus for a gated oscillator in digital circuits

• US 6,633,203 B1
• Filed: 04/25/2000
• Issued: 10/14/2003
• Est. Priority Date: 04/25/2000
• Status: Expired due to Fees

• Current Assignee: National University of Singapore
• Original Assignee: National University of Singapore
• Inventors: Joe, Jurianto
• Primary Examiner(s): KINKEAD, ARNOLD M
• Application Number:
  US09/558,082
• Time in Patent Office: 1,267 Days
• Field of Search: 331/111, 331/74, 331/173, 331/36.L, 331/172
• US Class Current: 331/173
• CPC Class Codes: H03K 5/00006 Changing the frequency modulating pulses H03K7/00; frequency dividers H03K21/00 - H03K29/00; additive or subtractive mixing of two pulse rates into one G06F7/605; pulse rate dividers G06F7/68

Abstract

A gated oscillator is provided for digital circuits. The gated oscillator is achieved by the unconventional use of controlling the operating point of a Van der Pol oscillator. Oscillations are achieved by Van der Pol self-oscillation behavior. The result is a highly simplified gated oscillator circuit for many digital circuit applications

Claims

1. A method for providing pulses in a digital circuit comprising steps of:

providing a digital circuit;

providing a clocking circuit, said clocking circuit coupled to said digital circuit,

said clocking circuit having an input terminal and an output terminal, said clocking circuit further having a variable operating point, said clocking circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said clocking circuit produces oscillatory output when said operating point is varied into said unstable region and said clocking circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said clocking circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said clocking circuit includes an element having negative impedance, said clocking circuit having a series input through an inductor, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor.

2. The method according to claim 1 wherein each said step of forcing includes applying a forcing function to said input of said clocking circuit, said forcing function having a first output level and a second output level, said clocking circuit characterized in that said operating point is located in said unstable region when said forcing function produces said first output level, said clocking circuit further characterized in that said operating point is located in one of said stable regions when said forcing function produces said second output level.

8. The method according to claim 1 wherein said element is a tunnel diode.

3. A method for providing pulses in a digital circuit comprising steps of:

providing a digital circuit;

providing a clocking circuit, said clocking circuit coupled to said digital circuit,

said clocking circuit having an input terminal and an output terminal, said clocking circuit further having a variable operating point, said clocking circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said clocking circuit produces oscillatory output when said operating point is varied into said unstable region and said clocking circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said clocking circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein each said step of forcing includes applying a forcing function to said input of said clocking circuit, said forcing function having a first output level and a second output level, said clocking circuit characterized in that said operating point is located in said unstable region when said forcing function produces said first output level, said clocking circuit further characterized in that said operating point is located in one of said stable regions when said forcing function produces said second output level, and

wherein said forcing function produces a third output level, said circuit characterized in that said operating point is located in a part of said unstable region, when said forcing function produces said third output level, that is different from the location of said operating point when said forcing function produces said first output level.

4. A method for providing pulses in a digital circuit comprising steps of:

providing a digital circuit;

providing a clocking circuit, said clocking circuit coupled to said digital circuit,

said clocking circuit having an input terminal and an output terminal, said clocking circuit further having a variable operating point, said clocking circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said clocking circuit produces oscillatory output when said operating point is varied into said unstable region and said clocking circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said clocking circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said clocking circuit includes an element having negative impedance, said clocking circuit having a series input through an inductor, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

wherein said forcing function is asymmetrical along a time axis.

5. A method for providing pulses in a digital circuit comprising steps of:

providing a digital circuit;

providing a clocking circuit, said clocking circuit coupled to said digital circuit,

said clocking circuit having an input terminal and an output terminal, said clocking circuit further having a variable operating point, said clocking circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said clocking circuit produces oscillatory output when said operating point is varied into said unstable region and said clocking circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said clocking circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said clocking circuit includes an element having negative impedance, said clocking circuit having a series input through an inductor, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

wherein said forcing function is cyclical.

6. A method for providing pulses in a digital circuit comprising steps of:

providing a digital circuit;

providing a clocking circuit, said clocking circuit coupled to said digital circuit,

said clocking circuit having an input terminal and an output terminal, said clocking circuit further having a variable operating point, said clocking circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said clocking circuit produces oscillatory output when said operating point is varied into said unstable region and said clocking circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said clocking circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said clocking circuit includes an element having negative impedance, said clocking circuit having a series input through an inductor, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

wherein said forcing function is a square wave.

7. A method for providing pulses in a digital circuit comprising steps of:

providing a digital circuit;

providing a clocking circuit, said clocking circuit coupled to said digital circuit,

said clocking circuit having an input terminal and an output terminal, said clocking circuit further having a variable operating point, said clocking circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said clocking circuit produces oscillatory output when said operating point is varied into said unstable region and said clocking circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said clocking circuit includes an operational amplifier circuit with feedback, said circuit having a series input through an inductor, wherein said unstable operating region is a negative resistance region, and wherein said operating point is forced into said unstable region by a changing voltage applied to said inductor.

9. In a digital circuit, a clocking circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said clocking circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said input,

said operating point is actively forced into said unstable region when said function generator output is at said first level,

said clocking circuit further adapted so that said operating point is actively forced to said stable region when said function generator output is at said second level,

wherein said clocking circuit includes an element having negative impedance, said clocking circuit having an inductor serially connected to said input, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor.

14. The digital circuit of claim 9 wherein said element is a tunnel diode.

10. In a digital circuit, a clocking circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said circuit input,

said operating point is forced into said unstable region when said function generator output is at said first level,

said circuit further adapted so that said operating point is forced to said stable region when said function generator output is at said second level,

wherein said function generator produces an output of a third level;

said operating point is forced into said unstable region when said function generator output is at said third level;

said operating point being located in said unstable region based on whether said function generator output is at said first level or said third level.

11. In a digital circuit, a clocking circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said input,

said circuit including an element having negative impedance, said circuit having an inductor serially connected to said input, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

said operating point is forced into said unstable region when said function generator output is at said first level,

said circuit further adapted so that said operating point is forced to said stable region when said function generator output is at said second level,

wherein said function generator produces a cyclical output.

12. In a digital circuit, a clocking circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said input,

said circuit including an element having negative impedance, said circuit having an inductor serially connected to said input, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

said operating point is forced into said unstable region when said function generator output is at said first level,

said circuit further adapted so that said operating point is forced to said stable region when said function generator output is at said second level,

wherein said function generator output produces a square wave.

13. In a digital circuit, a clocking circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said input,

said circuit including an element having negative impedance, said circuit having an inductor serially connected to said input, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

said operating point is forced into said unstable region when said function generator output is at said first level,

said circuit further adapted so that said operating point is forced to said stable region when said function generator output is at said second level,

wherein said function generator output has an asymmetrical shape.

15. A method for providing clocking pulses, comprising:

providing a circuit having an input terminal and an output terminal, said circuit further having a variable operating point, said circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said circuit produces oscillatory output when said operating point is varied into said unstable region and said circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

actively forcing said operating point into said unstable region to initiate operation of said circuit to produce at least one oscillation; and

actively forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said circuit includes an element having negative impedance, said circuit having an inductor serially connected to said input terminal, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor.

16. The method according to claim 15 wherein each said step of forcing includes applying a forcing function to said input of said circuit, said forcing function having a first output level and a second output level, said circuit characterized in that said operating point is located in said unstable region when said forcing function produces said first output level, said circuit further characterized in that said operating point is located in one of said stable regions when said forcing function produces said second output level.

17. A method for providing clocking pulses, comprising:

providing a circuit having an input terminal and an output terminal, said circuit further having a variable operating point, said circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said circuit produces oscillatory output when said operating point is varied into said unstable region and said circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

forcing said operating point into said unstable region to initiate operation of said circuit to produce at least one oscillation; and

forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein each said step of forcing includes applying a forcing function to said input of said circuit, said forcing function having a first output level and a second output level, said circuit characterized in that said operating point is located in said unstable region when said forcing function produces said first output level, said circuit further characterized in that said operating point is located in one of said stable regions when said forcing function produces said second output level,

wherein said forcing function produces a third output level, said circuit characterized in that said operating point is located in a part of said unstable region, when said forcing function produces said third output level, that is different from the location of said operating point when said forcing function produces said first output level.

18. A method for providing clocking pulses, comprising:

providing a circuit having an input terminal and an output terminal, said circuit further having a variable operating point, said circuit further having a transfer function characterized by having an unstable operating region bounded by a first stable operating region and a second stable operating region so that said circuit produces oscillatory output when said operating point is varied into said unstable region and said circuit has a non-oscillatory output when said operating point is varied into either of said first and second stable regions;

forcing said operating point into said unstable region to initiate operation of said circuit to produce at least one oscillation; and

forcing said operating point to vary into either one of said stable operating regions in order to terminate said at least one oscillation without transient effects,

wherein said circuit includes an operational amplifier circuit with feedback, said circuit having a series input through an inductor, wherein said unstable operating region is a negative resistance region, and wherein said operating point is forced into said unstable region by a changing voltage applied to said inductor.

19. A gated oscillator circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said input,

wherein said circuit includes an element having negative impedance, said circuit having an inductor serially connected to said input, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

said operating point is actively forced into said unstable region when said function generator output is at said first level,

said circuit further adapted so that said operating point is actively forced to said stable region when said function generator output is at said second level.

20. A gated oscillator circuit, comprising:

a circuit having an input and an output, said circuit having a transfer function, said transfer function having an unstable operating region bounded by a first stable operating region and by a second stable operating region, said transfer function defining a set of operating points of said circuit, said circuit adapted to produce oscillatory output when said operating point is varied into said unstable region, said circuit further adapted to produce a non-oscillatory output when said operating point is varied into either of said first and second stable regions; and

a function generator having an output adapted to selectively produce an output of a first level and an output of a second level, said function generator output coupled to said input,

wherein said circuit includes an element having negative impedance, said circuit having an inductor serially connected to said input, wherein said unstable operating region is a negative impedance region, and wherein said operating point is forced into said unstable region by a changing current applied through said inductor,

said operating point is forced into said unstable region when said function generator output is at said first level,

said circuit further adapted so that said operating point is forced to said stable region when said function generator output is at said second level,

wherein said function generator produces an output of a third level, said operating point is forced into said unstable region when said function generator output is at said third level, said operating point being located in said unstable region based on whether said function generator output is at said first level or said third level.