WO2009111038A1

WO2009111038A1 - Bidirectional-injection coupled oscillator

Info

Publication number: WO2009111038A1
Application number: PCT/US2009/001403
Authority: WO
Inventors: Mohammad Hekmat; Reza Navid; Nhat Nguyen
Original assignee: Rambus, Inc.
Priority date: 2008-03-05
Filing date: 2009-03-03
Publication date: 2009-09-11

Abstract

An oscillator (102) includes bidirectional-injection technology to permit phase cancellation of coupled signals for phase injection of energy into the oscillator substantially in phase with the oscillator's internal energy. In an example embodiment, the oscillator includes at least two energy phase injectors or couplers configured to generate and inject energy at balanced phases with respect to the phase of the energy of the tank's energy- injecting component. The couplers of the oscillator may be coupled with multiple oscillators in a multiphase configuration for generation of multiphase signals. The signals may be utilized as multiphase clock signals, such as quadrature clock signals. Such oscillators may, for example, be implemented as clock generators for timing of synchronous data systems or for modulation, detection and/or image rejection in radio- frequency and high speed communications.

Description

BIDIRECTIONAL- INJECTION COUPLED OSCILLATOR

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of Application Serial No. 61/068,401, filed March 5, 2008, entitled BIDIRECTIONAL-INJECTION COUPLED OSCILLATOR, the disclosure of which is hereby incorporated herein by reference. BACKGROUND OF THE TECHNOLOGY

[0002] Communications and data systems are driven to perform at ever increasing speed and efficiency. Faster transfers of increasing quantities of information can place great performance demands on the devices involved in these transfers. For example, digital systems utilize clock signals from a clock generator, of which an oscillator is a typical component, to synchronize and regulate activity between circuit blocks or devices. As data signals pass from one circuit element to another or between circuits of a synchronous digital system, the clock signal oscillating between high and low voltage levels coordinates the actions of two or more elements of the circuits so that data signals may be accurately processed.

[0003] In some synchronous systems multiple clock signals may be generated where each clock signal has a predictable relative phase offset from the other clock signals. For example, in one type of quadrature clocking system, timing circuits generate two clock signals that are ninety degrees out-of -phase with each other. Such quadrature clock signals can be used together to improve the performance of a system so that it matches the performance of a system which uses a higher- frequency clock signal .

[0004] Improving the frequency and phase accuracy as well as the frequency stability of the components involved in generating such signals can be significant for increasing system performance and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The present technology is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements including:

[0006] FIG. 1 is a block diagram of an example embodiment of an oscillator of the present bidirectional-injection technology; [0007] FIG. IA is a phase diagram illustrative of bidirectional signals involved in embodiments of the present technology; [0008] FIG. 2 is a further example embodiment of an oscillator; [0009] FIG. 3 shows the oscillator embodiment of FIG. 2 coupled with multiple oscillators;

[0010] FIG. 4 illustrates an example coupling of oscillators of the present technology suitable for generating quadrature clock signals; and

[0011] FIG. 5 is the phase relationship vector diagram for the oscillator configuration of FIG. 4. DETAILED DESCRIPTION

[0012] Fig. 1 illustrates an apparatus suitable for implementing the present bidirectional coupling oscillation technology. According to some embodiments, oscillator 102 includes an energy reserve unit such as an LC tank 104, an energy- injecting component 106 and couplers 112A, 112B. Typically, the energy reserve unit will be formed by an LC tank, such as one that includes one or more capacitors and one or more inductors connected in a parallel or serial configuration. The LC tank 104 may be configured to generate an output signal which will oscillate and may be considered an output oscillation signal 108. The frequency of the output oscillation signal 108 of the LC tank 104 will depend on the LC tank's characteristics (e.g., the chosen inductance and capacitance of the tank) . The relative phase of the output oscillation signal 108 generated by the LC tank 104 will depend on the phase of the collective energy injected into the LC tank. [0013] Because the LC tank 104 typically includes some parasitic resistance that will reduce the energy of the tank and thereby dampen the oscillations of the LC tank 104 from an original energy supply, the energy- injecting component 106 replenishes the loss of energy due to the positive resistance of the LC tank to maintain oscillation of the LC tank 104. Such a component 106 may be considered a negative resistance element with respect to the parasitic resistance of the LC tank 104. Thus, the signal output from the energy- injecting component 106 may be considered a negative resistance signal 105 (also shown as I_N in FIG. 1) that injects or supplies supplemental energy (e.g., current) into the LC tank 104 to compensate for the parasitic resistance of the LC tank's elements. Thus, the energy- injecting component 106 is an active element. The energy- inj ecting component may, for example, be implemented with transistors formed as a cross- coupled pair, which can be connected with an energy source (not shown in Fig. 1) . The frequency and phase of the negative resistance signal 105 (I_N) may vary but will typically be that of the resonant frequency and phase of the output oscillation signal 108 from the LC tank 104.

[0014] To set the oscillation of the tank to a desired phase, two or more coupling signals HOA, HOB (also shown as Ic(n-i) and Ic(n₊i) in FIG. 1 respectively) are also produced or supplied to inject energy into the LC tank 104. These signals may be generated respectively by two or more couplers 112A, 112B that may serve as phase-coupling components. The couplers may, for example, be implemented with a phase controlled transistor pair and connected with an energy source (not shown in FIG. 1) . As will be explained in more detail herein, in certain embodiments, the couplers 112B and 112A may be controlled by output signals of additional oscillators. In such a case, the phase of the output oscillation signal 108 may have a certain phase difference relative to other output oscillation signals of the other oscillators. The additional oscillators may be configured with the same circuit elements as discussed with respect to the oscillator 102 of Fig. 1.

[0015] Generally, the coupling signals from the couplers 112A, 112B and the negative resistance signal from the energy-injecting component will be generated with a common frequency. However, the couplers 112A, 112B will be configured and arranged to operate such that the coupling signals that they generate have phases that are different or offset from each other and different or offset from the phase of the negative resistance signal 105. Moreover, these signals may be generated such that the degree of each of the phases of the coupling signals cancel so that a signal resulting from their combination will have a phase approximately equal to that of the phase of the negative resistance signal 105 at the time of their injection into the LC tank 104. In this sense, the phases of the coupling signals are balanced with respect to the phase of the internal energy of the oscillator.

[0016] For example, a combination of the coupling signals from at least two couplers is illustrated in the phase diagram of Fig IA. As illustrated, a first coupling signal shown as I_C<_N-D has a first phase of +θ. A second coupling signal shown as I_C(_N+D has a second phase of -θ. As illustrated, the phase of the first coupling signal of I_C(_N-D lags the phase of the negative resistance signal (shown as I_N) and the phase of the second coupling signal of I_C(N+D leads the phase of the negative resistance signal. Thus, when the coupling signals are combined, the resultant signal (shown as I_C(N-D + I_C(_N+D) has a phase that is substantially equal to the phase of the negative resistance signal. Thus, when the coupling signals are combined, they will be substantially in phase with the negative resistance signal (and the oscillations of the LC tank) . Accordingly, when the coupling signals are combined with the negative resistance signal for injecting the joint energy into the tank 104, they will generally be in phase with the internal enerqy of the tank 104 [0017] In the illustrated example of FIG. 1 with only two coupling signals, the absolute value of the degree of the phases of the coupling signals relative to the negative resistance signal (or the oscillation energy of the tank) are substantially equal as shown in FIG. IA. However, other combinations of coupling signals in addition to two may also be implemented to arrive at a resultant signal substantially in phase with the negative resistance signal and thus, the oscillations of the LC tank 104. Thus, although it may, each coupling signal need not have an absolute phase value equal to one or more of the other coupling signals so long as the collective phases of the coupling signals are balanced or cancel with respect to the phase of the negative resistance signal or the phase of the energy of the LC tank as illustrated in FIG. IA.

[0018] A potential benefit of such coupling signal phase cancellation may be understood when considering the effect of operation of an oscillator coupled in a multiphase configuration without phase coupling cancellation, such as a system with only one of the coupling signals illustrated in FIG. IA. In such an oscillator, the total energy (e.g., current) flowing into the LC tank is the sum of the coupling energy and the energy from its energy- injecting component, which are not in phase. Therefore, the total LC tank injection energy has a phase difference with respect to the voltage across the LC tank. This must be compensated for by the LC tank impedance. For example, in the case of a quadrature oscillator that includes two coupled oscillators, the current injected into each LC tank from a single coupling signal of another oscillator is in quadrature with respect to the current of the oscillator itself. This requires the LC tank impedance to have -θ degrees of phase. Having a nonzero phase also suggests that the LC tank is operating at an offset from its resonant frequency (i.e., the frequency of operation is not the same as the resonant frequency of the LC tank used in the oscillator) . Consequently, such a coupled does so at the expense of operating at frequency offsets from the resonance frequency of the LC tank employed in them. This property can result in two major issues: degraded phase noise due to lower effective Q and more significantly, the potential of frequency ambiguity. In particular, frequency ambiguity appears to be a serious issue because the output frequency of these oscillators may vary depending on the initial conditions and other parameters in the circuit that are not directly or easily controllable by the designer.

[0019] In an oscillator of the present technology, which may also be implemented in a multi-phase generation implementation, all oscillators in the loop can be configured to operate at the nominal resonance frequency of the LC tank due to the coupling phase cancellation. This can result in an improvement or elimination of frequency ambiguity and/or phase noise degradation.

[0020] An oscillator 202 of the present technology is further illustrated in an example circuit diagram of FIG. 2. Inductors 220A, 220B and variable capacitors 222A, 222B form an LC tank, such as LC tank 104 of Figure 1. A cross-coupled transistor pair 224 forms the energy- injecting component to inject a negative resistance signal 205 into the LC tank. Complementary versions of the output oscillation signal from the tank may be taken at points V(_N)+ or V_(N)-. Transistors 226A, 226B form a first coupler that produces a first coupling signal 210A which is also shown as I_c(N-i) in Fig. 2. Transistors 228A, 228B form a second coupler that produces a second coupling signal 210B which is also shown as Ic(N_+D iⁿ Fig- 2. The gates of transistors 226A, 226B may be respectively coupled with the negative and positive versions of an oscillation output signal (shown as V(_N-D- and V(_N-D+ in FIG. 2) of an oscillator (not shown) to serve as control signals for activating these transistors and thereby control the energy injected into the LC tank. Similarly, the gates of transistors 228A, 228B may be respectively coupled with the negative and V(_N+I)- and V(_N+1)+ in FIG. 2) of another oscillator (not shown) to serve as control signals for activating these transistors to control the energy injected in the tank.

[0021] Coupling of an oscillator 302N of the present technology- is further illustrated in FIG. 3. The figure illustrates a connection of additional oscillators 302 (N+l) , 302(N-I) with oscillator 302(N) . Typically, the components of each oscillator may be configured alike, and may also be of the type that includes the oscillator components illustrated in FIG. 2. As illustrated in FIG. 3, the coupling signals 310A, 310B of oscillator 302 (N) are controlled by the output oscillation signals 308(N-I), 308 (N+l) (also shown as V(N-I)+/- and V(N+1)+/- in FIG. 3) . The output oscillation signals 308 (N+l) and 308 (N-I) are generated by oscillator 302 (N+l) and oscillator 302 (N-I) respectively. These signal controls are coupled to the transistors regulating the injection of the coupling signals 310A, 310B into the tank of oscillator 302(N) . Thus, the complementary versions of the output oscillation signal 308 (N+l) of oscillator 302 (N+l) control transistors 328A and 328B. Furthermore, the complementary versions of the output oscillation signal 308 (N-I) of oscillator 302(N-I) control transistors 326A and 326B respectively. In this embodiment, unlike the embodiment of FIG. 2, a common current source 330 is implemented with the tails of the couplers and energy- injecting component. However, like FIG. 2, separate sources may also be utilized for each tail. [0022] Similarly, oscillator 302 (N) supplies output oscillation signals 308 (N) to in part control the coupling signals of oscillator 302 (N+l) and oscillator 302(N-I) . Additional control signals for controlling the coupling signals of oscillators 302 (N+l) , 302(N-I) may be supplied by still additional oscillators (not shown) . However, such control signals may be supplied by further coupling the output oscillation signals of oscillator 302(N-I) with the injection related transistors of oscillator 302 (N+l) and by further coupling the output related transistors of oscillator 302(N-I) (not shown) . By- coupling multiple oscillators in such a fashion, multiphase output oscillation signals may be produced such that each N oscillator generates an output oscillation signal with a constant phase difference with a next N+l oscillator by a degree that is a function of the number of oscillators coupled together. [0023] An example of such multiphase generation is illustrated in the coupling of oscillators of the present technology shown in FIG. 4. The arrangement includes four oscillators 402-1, 402-2, 402-3, 402-4 for producing quadrature clock signals. Each oscillator may be constructed as described with respect to FIG. 1. Each oscillator provides output oscillation signals to each neighbor oscillator. Thus, oscillator 402-1 supplies output oscillation signals 408-1 (also labeled as +/-V₁ in Fig. 4) to both neighbor oscillators 402-2 and 402-4. Oscillator 402-2 supplies output oscillation signals 408-2 (also labeled as +/-V₂ in Fig. 4) to both neighbor oscillators 402-1 and 402-3. Oscillator 402-3 supplies output oscillation signals 408-3 (also labeled as +/-V₃ in Fig. 4) to both neighbor oscillators 402-2 and 402-4. Oscillator 402-4 supplies output oscillation signals 408-4 (also labeled as +/-V₄ in Fig. 4) to both neighbor oscillators 402-3 and 402-1.

[0024] In the case of the connections or couplings between oscillators 402-1 and 402-2, 402-2 and 402-3, 402-3 and 402-4, the couplings may be made as illustrated in FIG. 3. In other words, in such a loop configuration of N oscillators, the mutual connections between the 1^st and the 2^nd, the 2^nd and the 3^rd, ... the N- 1^st and the Nth oscillator may be made in the manner shown in FIG. 3. However, with respect to the coupling of output oscillation signals between oscillator 402-1 and oscillator 402- 4, the output oscillation signals may be inverted to permit a 180 degree phase inversion around the loop of oscillators. Thus, in the case of loop configuration of N oscillators, the output from the first oscillator to the Nth oscillator and the output from

<_i.ι<_^; K.ii U-H-J.iJ.aLUJ. L. ^J L..J.G J--LXOL. UDl-lliαLυi W-L-L-L UC -LIlVCJ- LCU . -Lll-Lto permits a full rotation of the phases of the signals between existing oscillators but with fewer oscillators than what would otherwise be required without such inversion 440. In the illustrated embodiment, such inversion may be accomplished by reversing the connections of the positive and negative versions of the output oscillation signal 408-4 of oscillator 402-4 at the transistors of oscillator 402-1. Similarly, the connections of the positive and negative versions of the output oscillation signal 408-1 of oscillator 402-1 may be reversed at the transistors of oscillator 402-4. However, such a reversing of the output signals between the first and Nth oscillators might be optional if further oscillators are utilized in the loop. [0025] FIG. 5 illustrates the phase relationship of the output oscillation signals of the oscillators of FIG. 4. Due to the chosen number of oscillators and their coupling with each other, the output oscillation signals from each (shown as + or - V_N) are each forty five degrees out of phase with the signals of the immediately preceding oscillator. Thus, this arrangement of oscillators with this production of output oscillation signals may be conveniently utilized for the generation of quadrature clock signals.

[0026] Generally, the oscillator or oscillators of the present technology can be implemented as part of a data or communications system, such as a system that transmits data on a signal bus or in wireless communications, or a system that synchronizes operations based on a particular system or device clock. For example, the oscillators may be implemented in one or more timing generators or clock generators of a memory controller and/or memory component . These components may be formed as part of an integrated circuit chip with circuits of a memory controller or memory or other devices and they may participate in timing of read and write data transmission operations across a signal bus. However, the components may also be formed on additional integrated circuit chips separate from controller and memory as discussed in more detail herein. Merely by way of example, the circuits may also form parts of a single computer system or other electronic or processing device such as part of a central processing unit. By way of further example, the components of the technology may be formed or used in or with the components of communication devices for modulation, detection and/or image rejection, such as in radio- frequency and high speed wireless and/or wire line communications. The oscillators may be used in such devices to generate two-phase quadrature signals to increase spectral efficiency and data rate, such as in transmitter and receiver devices and circuits.

[0027] In general, each of the circuits implemented in the technology presented herein may be constructed with electrical elements such as traces, capacitors, inductors, resistors, transistors, registers, latches etc. and may be based on metal oxide semiconductor (MOS) technology, but may also be implemented using other technology such as bipolar technology or any other technology in which a signal -controlled current flow may be achieved.

[0028] Furthermore, these circuits may be constructed using automated systems that fabricate integrated circuits. For example, the components and systems described may be designed as one or more integrated circuits, or a portion (s) of an integrated circuit, based on design control instructions for doing so with circuit -forming apparatus that controls the fabrication of the blocks of the integrated circuits. The instructions may be in the form of data stored in, for example, a computer-readable medium such as a magnetic tape or an optical or magnetic disk. The design control instructions typically encode data structures or other information describing the circuitry that can be physically created as the blocks of the integrated circuits. Although any appropriate format may be used for such encoding, such data structures are commonly written in Caltech Intermediate Format (CIF) , Calma GDS II Stream Format (GDSII) , or Electronic integrated circuit design can develop such data structures from schematic and flow diagrams of the type detailed above and the corresponding descriptions and encode the data structures on computer readable medium. Those of skill in the art of integrated circuit fabrication can then use such encoded data to fabricate integrated circuits comprising one or more of the circuits described herein.

[0029] In the foregoing description and in the accompanying drawings, specific terminology and drawing symbols are set forth to provide a thorough understanding of the present technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. For example, although the terms "first", "second" and "third" have been used herein, unless otherwise specified, the language is not intended to provide any specified order or number limit but is merely to assist in explaining elements of the technology. [0030] Moreover, although the technology herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the technology. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the technology. For example, the phase coupling signal cancellation may be applied to different types of oscillators in addition to the types of oscillators illustrated herein. Moreover, any number of oscillators may be coupled as discussed herein to produce other multiphase clock signal relationships in addition to the example quadrature relationship explained herein.

Claims

CLAIMS :

1 . An apparatus comprising : a first oscillator having an LC tank and an energy- injecting component to inject a first signal, having a first phase, into the LC tank, wherein the LC tank has a resonant frequency; a first coupler to inject a second signal into the LC tank, the second signal having a second phase; a second coupler coupled to inject a third signal into the LC tank, the third signal having a third phase; wherein the first phase, the second phase and third phase are different phases.

2. The oscillator apparatus of claim 1 wherein a combination of the second phase and third phase comprises a resultant phase approximately equal to the first phase.

3. The oscillator apparatus of claim 1 wherein the first oscillator comprises a first terminal and a second terminal, wherein the first terminal is coupled to inject an output signal into a second oscillator and wherein the second terminal is coupled to inject an output signal into a third oscillator.

4. The oscillator apparatus of claim 1 wherein the first coupler is coupled to an output of a second oscillator to provide an output signal to control injection of the second signal and wherein the second coupler is coupled to an output of a third oscillator to provide an output signal to control injection of the third signal .

5. The oscillator apparatus of claim 4 wherein the first coupler and the second coupler each comprise a pair of transistors .

6. The oscillator apparatus of claim 4 wherein the first oscillator, the second oscillator and the third oscillator are each formed by the same combination of circuit elements.

7. The oscillator apparatus of claim 4 further comprising a fourth oscillator, and wherein the oscillators generate a set of oscillating output signals in quadrature.

8. A device comprising: an inductor-capacitor tank to generate an oscillation output ; an energy-injecting component to inject a first signal into the tank to compensate for energy loss of the tank, the first signal having a first phase,- a first transistor pair to inject a second signal into the tank, the second signal having a second phase; and a second transistor pair to inject a third signal into the tank, the third signal having a third phase, wherein the first phase, second phase and third phases are each offset from one another.

9. The device of claim 8 wherein the second phase leads the first phase by a degree approximately equal to a degree that the third phase lags the first phase.

10. The device of claim 8 wherein a gate of the first transistor pair is coupled to an output of a first oscillator and wherein a gate of the second transistor pair is coupled to an output of a second oscillator.

11. The device of claim 10 wherein the oscillation output comprises a first output signal and a second output signal, and wherein the first output signal is input to the first oscillator to control an injection transistor of the first oscillator and the second output signal is input to the second oscillator to control an injection transistor of the second oscillator.

12. The device of claim 11 wherein the oscillation output and an output of the first or second oscillator comprise a pair of quadrature signals.

13. The device of claim 12 wherein the device is formed on a part of an integrated chip.

14. A method of generating an oscillation signal comprising : producing a first signal having a first phase; producing a second signal having a second phase; and injecting the first signal and the second signal into an oscillator, the oscillator to generate an oscillation signal of a third phase, wherein the first phase, second phase and third phase are different phases.

15. The method of claim 14 wherein the first phase leads the third phase by a degree approximately equal to a degree that the second phase lags the third phase.

16. The method of claim 14 wherein the oscillator comprises an inductor-capacitor tank and a cross-coupled transistor pair.

17. The method of claim 14 wherein the oscillation signal oscillates at a resonance frequency of the oscillator.

18. The method of claim 14 wherein output signals of the oscillator control additional oscillators.

19. A timing signal generator comprising: tank means for oscillating at a resonant frequency; negative resistance means coupled with the tank means for injecting a first signal at a first phase into the tank means ; first injection means coupled to the tank means for injecting a second signal at a second phase into the tank means; second injection means coupled to the tank means for injecting a third signal at a third phase to the tank means, wherein the first phase, second phase and third phase are different phases.

20. The timing generator of claim 19 wherein a combination of phases including the second phase and the third phase is substantially in phase with the first phase.

21. The timing generator of claim 19 further comprising first, second and third oscillator means for generating an oscillating output, wherein two of the oscillator means are each bi-directionally coupled with the tank means and one of the first injection means and the second injection means.

22. An information-bearing medium having computer-readable information thereon, the computer-readable information to control a circuit -forming apparatus to form a block of an integrated circuit, the computer-readable information comprising: instructions to form a first oscillator comprising an inductor-capacitor tank, a cross-coupled transistor pair coupled to the tank to inject a first signal at a first phase to compensate for resistance of the tank; a first transistor pair coupled to the tank to inject a second signal at a second phase into the tank; and a second transistor pair coupled to the tank to inject a third signal at a third phase into the tank; instructions to form a second oscillator having an output coupled to control a transistor of the first transistor pair; instructions to form a third oscillator having an output coupled to control a transistor of the second transistor pair; wherein first phase, second phase and third phase are different phases.

23. The information-bearing medium of claim 22 wherein the instructions form the first oscillator, second oscillator and third oscillator such that the combined phases of the second phase and the third phase are substantially equal to the first phase.

24. The information-bearing medium of claim 22 wherein the instructions to form the first oscillator, second oscillator and third oscillator form each of the oscillators with the same circuit element configuration.

25. The information-bearing medium of claim 22 further comprising instructions to form a fourth oscillator coupled with the first and second oscillators, the oscillators to form a quadrature clock generator.

26. An integrated circuit comprising: first, second, and third oscillators, each oscillator having first and second inputs and first and second outputs; wherein the first oscillator is bidirectionally coupled to the two other oscillators such that (a) the first oscillator inputs a first control signal at a first phase from one of the two others and a second control signal at a second phase from the other of the two others, and (b) the first oscillator outputs a third control signal at a third phase to one of the two others and a fourth control signal at a fourth phase to the other of the two others; wherein the first phase and second phase are different phases .

27. The integrated circuit of claim 26 wherein a combination of the first phase and the second phase are substantially in phase with a phase of a negative resistance signal of the first oscillator.

28. The integrated circuit of claim 26 further comprising a fourth oscillator, wherein each oscillator is bidirectionally coupled to two others of the oscillators such that each oscillator accepts a first control signal at a first phase from one of the two others and a second control signal at a second phase from the other of the two others.

29. The integrated circuit of claim 26 wherein each oscillator comprises an inductor-capacitor tank, a cross-coupled transistor pair coupled to the tank to inject current into the tank to compensate for resistance of the tank; a first transistor pair coupled to the tank to inject current into the tank under the control of another of the oscillators and a second transistor pair coupled to the tank to inject current into the tank under control of another of the oscillators.

30. A system comprising: a plurality of oscillators coupled to generate multiphase clock signals, each oscillator being coupled to other oscillators to inject at least two coupled signals into the oscillator, at least two coupled signals having different phases, wherein the coupled signals of the oscillator cancel to a degree to produce a signal in phase with the internal energy of the oscillator.

31. The system of claim 30 wherein the system comprises a clock generator and a dynamic random access memory.

32. The system of claim 30 wherein the system comprises a clock generator and a dynamic random access memory controller.

33. The system of claim 30 wherein the system comprises a communications device.

34. The system of claim 30 wherein the multiphase clock signals are in quadrature clock signals.