The present invention relates in general to high speed logic circuitry, and in particular to current-controlled CMOS (or C3MOS™) logic circuits with inductive broadbanding.
For a number of reasons CMOS is the logic family of choice in today's VLSI devices. Due to the complementary nature of its operation, CMOS logic consumes zero static power. CMOS also readily scales with technology. These two features are highly desirable given the drastic growth in demand for low power and portable electronic devices. Further, with the computer aided design (CAD) industry's focus on developing automated design tools for CMOS based technologies, the cost and the development time of CMOS VLSI devices has reduced significantly.
The one drawback of the CMOS logic family, however, remains its limited speed. That is, conventional CMOS logic has not achieved the highest attainable switching speeds made possible by modern sub-micron CMOS technologies. As a result of the speed limitations of conventional CMOS logic, integrated circuit applications in the Giga Hertz frequency range have had to look to alternative technologies such as ultra high speed bipolar circuits and Gallium Arsenide (GaAs). These alternative technologies, however, have drawbacks of their own that have made them more of a specialized field with limited applications as compared to silicon MOSFET that has had widespread use and support by the industry. In particular, compound semiconductors such as GaAs are more susceptible to defects that degrade device performance, and suffer from increased gate leakage current and reduced noise margins. Furthermore, attempts to reliably fabricate a high quality oxide layer using GaAs have not thus far met with success. This has made it difficult to fabricate GaAs FETs, limiting the GaAs technology to junction field-effect transistors (JFETs) or Schottky barrier metal semiconductor field-effect transistors (MESFETs). A major drawback of the bipolar technology, among others, is its higher current dissipation even for circuits that operate at lower frequencies.
A significant improvement in speed of operation of CMOS circuitry has been achieved by a family of CMOS logic that is based on current-controlled mechanism. Current-controlled CMOS (or C3MOS) logic is described in greater detail in commonly-assigned patent application Ser. No. 09/484,856, entitled “Current-Controlled CMOS Logic Family,” by Hairapetian, which is hereby incorporated in its entirety for all purposes. The basic building block of the C3MOS logic family uses a pair of conventional MOSFETs that steer current between a pair of load devices in response to a difference between a pair of input signals. Thus, unlike conventional CMOS logic, C3MOS logic dissipates static current, but operates at much higher speeds.
According to one aspect of the invention, to further enhance speed of operation of circuits implemented in CMOS technology, the present invention introduces inductive elements in the C3MOS circuits. In a specific embodiment, a spiral inductor is inserted in series with the load devices of selected C3MOS structures that process high-bandwidth data signals. The resulting series combination of inductor and resistive element (e.g., polysilicon resistors) that is in parallel with an existing capacitive load provides a high impedance at a higher bandwidth than would be possible without the presence of the inductor. Optimized values for the inductors ensure appropriate placement of the circuit's natural frequencies in the complex plane to achieve fast rise and fall times with appropriate overshoot and undershoot. The present invention combines the use of this type of shunt peaking with C3MOS circuits that process broadband bi-level (i.e., digital as opposed to analog) differential signals. The combination of these characteristics allows for improvement of the output signal's inter-symbol interference without any increase in power dissipation.
According to another aspect of the invention, a multiplexer circuit includes C3MOS with inductive broadbanding to facilitate operation at ultra-high frequencies.
According to another aspect of the invention, a flip-flop is implemented utilizing C3MOS with inductive broadbanding to operate at ultrahigh frequencies.
According to another aspect of the invention, a complementary metal-oxide-semiconductor (CMOS) logic circuitry combines on the same silicon substrate, current-controlled MOSFET circuitry of the type described above for high speed signal processing, with conventional CMOS logic that does not dissipate static current. Examples of such combined circuitry include serializer/deserializer circuitry used in high speed serial links, high speed phase-locked loop dividers, and the like.
Other features and advantages of the invention will be apparent in view of the following detailed description and appended drawings.
FIG. 2(a) is a schematic diagram of the circuit of
FIG. 2(b) is a simplified diagram depicting the transient behavior of the circuit of FIG. 2(a);
FIG. 2(c) is a graph depicting the difference between ideal and C3MOS step responses;
FIG. 4(a) is a graph depicting inter-symbol interference (ISI) vs. input pulse width for five values of series inductance;
FIG. 4(b) is a graph depicting the output signal of the circuit of
FIG. 6(a) is a schematic diagram of a serializer circuit utilizing features of the invention;
FIG. 6(b) is a more detailed depiction of the 2:1 MUX depicted in FIG. 6(a);
The present invention provides ultra high-speed logic circuitry implemented in silicon complementary metal-oxide-semiconductor (CMOS) process technology. A distinction is made herein between the terminology “CMOS process technology” and “CMOS logic.” CMOS process technology as used herein refers generally to a variety of well established CMOS fabrication processes that form a field-effect transistor over a silicon substrate with a gate terminal typically made of polysilicon material disposed on top of an insulating material such as silicon dioxide. CMOS logic, on the other hand, refers to the use of complementary CMOS transistors (n-channel and p-channel) to form various logic gates and more complex logic circuitry, wherein zero static current is dissipated. The present invention uses current-controlled mechanisms with inductive broadbanding to develop a family of very fast current-controlled CMOS (or C3MOS™) with inductive broadbanding logic that can be fabricated using a variety of conventional CMOS process technologies, but that unlike conventional CMOS logic does dissipate static current. C3MOS with inductive broadbanding logic or current-controlled metal-oxide-semiconductor field-effect transistor (MOSFET) logic are used herein interchangeably.
In a preferred embodiment, the basic building block of this logic family is an NMOS differential pair with series connected inductive/resistive (LR) loads.
In
FIGS. 2(a) and (b) respectively depict the circuit of
In the circuit of FIG. 2(a) the transient response of the output signal would be controlled by the RC time constant. It is clear from FIG. 2(c) that the presence of the load resistor significantly slows down the transient step response. Thus, when an input signal is received with a very fast rise time the current increases rapidly to charge or discharge the load capacitor. However, the transient response of the output signal is controlled by the RC time constant and can have a longer rise time than the input pulse.
Now, considering the circuit as disclosed in
The larger the value of series inductance, the longer the full value of the current is available to charge/discharge the load capacitances.
From
From the FIG. 4(a) graphs it is apparent that given the values of R and CL, the optimum inductor value is given by:
LS(opt)=(0.35)*CLR2
FIG. 4(b) depicts the output signals for the circuit of
In one embodiment of the present invention a transceiver circuit along a fiber optic channel deserializes an input data stream with a bit rate of, for example, 10 Gb/s. After processing the lower frequency deserialized data, the data is serialized before transmission back onto the fiber channel. According to the present invention, those parts of this circuitry that process the highest speed data (e.g., input to the deserializer and output of the serializer) are implemented by C3MOS circuitry with inductive broadbanding.
FIG. 6(a) shows an exemplary 16:1 serializer according to the present invention. The serializer includes a 16:8 multiplexer 50 that converts the data rate to 1.25 Gb/s, followed by an 8:4 multiplexer 54 that converts the data rate to 2.5 Gb/s. The 2.5 Gb/s data is further converted to a 5 Gb/s data by a 4:2 multiplexer 56, and finally to a 10 Gb/s data by a 2:1 multiplexer 58. A flip flop 60 at the output re-times the 10 Gb/s data to generate the final output data stream.
According to this embodiment of the invention, the circuit of FIG. 6(a) may combine conventional CMOS logic used for the lower speed multiplexers and core processing circuitry, with C3MOS logic for the mid-rate multiplexers, and C3MOS logic with inductive broadbanding for the highest speed multiplexer (i.e., the 2:1 multiplexer 58) as well as the output re-timing flip flop 60.
As illustrated by the various C3MOS with inductive broadbanding logic elements described below, all of the building blocks of any logic circuitry can be constructed using the C3MOS with inductive broadbanding technique of the present invention. More complex logic circuits such as shift registers, counters, frequency dividers, etc., can be constructed in C3MOS with inductive broadbanding using the basic elements described above. As mentioned above, however, both C3MOS and C3MOS with inductive broadbanding logic does consume static power. Additionally, the fabrication of C3MOS with inductive broadbanding logic is more expensive than C3MOS or CMOS because of the need to add inductors to the IC.
The static current dissipation of C3MOS and/or C3MOS with inductive broadbanding may become a limiting factor in certain large scale circuit applications. In one embodiment, as depicted for example in FIGS. 5 and 6(a), the present invention combines C3MOS with inductive broadbanding and C3MOS logic with conventional CMOS logic to achieve an optimum balance between speed and power consumption. According to this embodiment of the present invention, an integrated circuit utilizes C3MOS with inductive broadbanding logic for the ultra high speed (e.g., 10 Gb/s) portions of the circuitry, C3MOS for very high speed parts of the circuit (e.g., 2.5-5 Gb/s), and conventional CMOS logic for the relatively lower speed sections. For example, to enable an integrated circuit to be used in ultra high speed applications, the input and output circuitry that interfaces with and processes the high speed signals is implemented using C3MOS with inductive broadbanding. The circuit also employs C3MOS to divide down the frequency of the signals being processed to a low enough frequency where conventional CMOS logic can be used. The core of the circuit, according to this embodiment, is therefore implemented by conventional CMOS logic that consumes zero static current.
FIG. 6(b) shows an implementation of the 2:1 multiplexer 58 wherein the actual output multiplexing circuit 62 uses C3MOS with inductive broadbanding an implementation of which is shown in FIG. 7.
It is to be understood that all C3MOS logic elements, numerous examples of which are described on the above-referenced commonly-assigned patent application, can employ the inductive broadbanding technique according to the present invention.
According to one embodiment of the present invention the combined C3MOS with inductive broadbanding /C3MOS /CMOS circuit technique is employed in a transceiver of the type illustrated in FIG. 9. The exemplary transceiver of
In conclusion, the present invention provides various circuit techniques for implementing ultra high speed circuits using current-controlled CMOS (C3MOS) logic and C3MOS with inductive broadbanding logic fabricated in conventional CMOS process technology. In one embodiment, the present invention advantageously combines high speed C3MOS with inductive broadbanding /C3MOS with inductive broadbanding /C3MOS logic with low power conventional CMOS logic. According to this embodiment circuits such as transceivers along fiber optic channels can be fabricated on a single chip where the ultra-high speed portions of the circuit utilize C3MOS with inductive broadbanding /C3MOS and the relatively lower speed parts of the circuit use conventional CMOS logic.
While the above is a complete description of the preferred embodiment of the present invention, it is possible to use various alternatives, modifications and equivalents. For example, although spiral inductors and poly resistors are utilized in the preferred embodiment other techniques known to persons of skill in the art can be utilized Therefore, the scope of the present invention should be determined not with reference to the above description but should, instead, be determined with reference to the appended claims, along with their full scope of equivalents.
This application is a continuation of and claims the benefit of U.S. provisional patent application No. 60/184,703, filed Feb. 24, 2000, the disclosure of which is incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
4333020 | Maeder | Jun 1982 | A |
4395774 | Rapp | Jul 1983 | A |
4449248 | Leslie et al. | May 1984 | A |
4519068 | Krebs et al. | May 1985 | A |
4545023 | Mizzi | Oct 1985 | A |
4599526 | Paski | Jul 1986 | A |
4649293 | Ducourant | Mar 1987 | A |
4680787 | Marry | Jul 1987 | A |
4727309 | Vajdic et al. | Feb 1988 | A |
4731796 | Masterton et al. | Mar 1988 | A |
4737975 | Shafer | Apr 1988 | A |
4761822 | Maile | Aug 1988 | A |
4777657 | Gillaspie | Oct 1988 | A |
4794649 | Fujiwara | Dec 1988 | A |
4804954 | Macnak et al. | Feb 1989 | A |
4806796 | Bushey et al. | Feb 1989 | A |
4807282 | Kazan et al. | Feb 1989 | A |
4817115 | Campo et al. | Mar 1989 | A |
4850009 | Zook et al. | Jul 1989 | A |
4890832 | Zomaki | Jan 1990 | A |
4894792 | Mitchell et al. | Jan 1990 | A |
4916441 | Gombrich | Apr 1990 | A |
4964121 | Moore | Oct 1990 | A |
4969206 | Desrochers | Nov 1990 | A |
4970406 | Fitzpatrick et al. | Nov 1990 | A |
4977611 | Maru | Dec 1990 | A |
4995099 | Davis | Feb 1991 | A |
5008879 | Fischer et al. | Apr 1991 | A |
5025486 | Klughart | Jun 1991 | A |
5029183 | Tymes | Jul 1991 | A |
5031231 | Miyazaki | Jul 1991 | A |
5033109 | Kawano et al. | Jul 1991 | A |
5041740 | Smith | Aug 1991 | A |
5055659 | Hendrick et al. | Oct 1991 | A |
5055660 | Bertagna et al. | Oct 1991 | A |
5079452 | Lain et al. | Jan 1992 | A |
5081402 | Koleda | Jan 1992 | A |
5087099 | Stolarczyk | Feb 1992 | A |
5115151 | Hull et al. | May 1992 | A |
5117501 | Childress et al. | May 1992 | A |
5119502 | Kallin et al. | Jun 1992 | A |
5121408 | Cai et al. | Jun 1992 | A |
5123029 | Bantz et al. | Jun 1992 | A |
5128938 | Borras | Jul 1992 | A |
5134347 | Koleda | Jul 1992 | A |
5142573 | Umezawa | Aug 1992 | A |
5150361 | Wieczorek et al. | Sep 1992 | A |
5152006 | Klaus | Sep 1992 | A |
5153878 | Krebs | Oct 1992 | A |
5175870 | Mabey et al. | Dec 1992 | A |
5177378 | Nagasawa | Jan 1993 | A |
5179721 | Comroe et al. | Jan 1993 | A |
5181200 | Harrison | Jan 1993 | A |
5196805 | Beckwith et al. | Mar 1993 | A |
5216295 | Hoang | Jun 1993 | A |
5230084 | Nguyen | Jul 1993 | A |
5239662 | Danielson et al. | Aug 1993 | A |
5241542 | Natarajan et al. | Aug 1993 | A |
5241691 | Owen | Aug 1993 | A |
5247656 | Kabuo et al. | Sep 1993 | A |
5249220 | Moskowitz et al. | Sep 1993 | A |
5249302 | Metroka et al. | Sep 1993 | A |
5265238 | Canova, Jr. et al. | Nov 1993 | A |
5265270 | Stengel et al. | Nov 1993 | A |
5274666 | Dowdell et al. | Dec 1993 | A |
5276680 | Messenger | Jan 1994 | A |
5278831 | Mabey et al. | Jan 1994 | A |
5289055 | Razavi | Feb 1994 | A |
5289469 | Tanaka | Feb 1994 | A |
5291516 | Dixon et al. | Mar 1994 | A |
5293639 | Wilson et al. | Mar 1994 | A |
5296849 | Ide | Mar 1994 | A |
5297144 | Gilbert et al. | Mar 1994 | A |
5301196 | Ewen et al. | Apr 1994 | A |
5319369 | Majos et al. | Jun 1994 | A |
5323392 | Ishii et al. | Jun 1994 | A |
5331509 | Kikinis | Jul 1994 | A |
5345449 | Buckingham et al. | Sep 1994 | A |
5349649 | Iijima | Sep 1994 | A |
5361397 | Wright | Nov 1994 | A |
5363121 | Freund | Nov 1994 | A |
5373149 | Rasmussen | Dec 1994 | A |
5373506 | Tayloe et al. | Dec 1994 | A |
5390206 | Rein et al. | Feb 1995 | A |
5392023 | D'Avello et al. | Feb 1995 | A |
5406615 | Miller, II et al. | Apr 1995 | A |
5406643 | Burke et al. | Apr 1995 | A |
5418837 | Johansson et al. | May 1995 | A |
5420529 | Guay et al. | May 1995 | A |
5423002 | Hart | Jun 1995 | A |
5426637 | Derby et al. | Jun 1995 | A |
5428636 | Meier | Jun 1995 | A |
5430845 | Rimmer et al. | Jul 1995 | A |
5434518 | Sinh et al. | Jul 1995 | A |
5438329 | Gastouniotis et al. | Aug 1995 | A |
5457412 | Tamba et al. | Oct 1995 | A |
5459412 | Mentzer | Oct 1995 | A |
5440560 | Rypinski | Nov 1995 | A |
5465081 | Todd | Nov 1995 | A |
5481265 | Russell | Jan 1996 | A |
5481562 | Pearson et al. | Jan 1996 | A |
5510734 | Sone | Apr 1996 | A |
5510748 | Erhart et al. | Apr 1996 | A |
5521530 | Yao et al. | May 1996 | A |
5533029 | Gardner | Jul 1996 | A |
5535373 | Oinowich | Jul 1996 | A |
5544222 | Robinson et al. | Aug 1996 | A |
5548230 | Gerson et al. | Aug 1996 | A |
5576644 | Pelella | Nov 1996 | A |
5579487 | Meyerson et al. | Nov 1996 | A |
5584048 | Wieczorek | Dec 1996 | A |
5600267 | Wong et al. | Feb 1997 | A |
5606268 | Van Brunt | Feb 1997 | A |
5625308 | Matsumoto et al. | Apr 1997 | A |
5628055 | Stein | May 1997 | A |
5630061 | Richter et al. | May 1997 | A |
5640356 | Gibbs | Jun 1997 | A |
5675584 | Jeong | Oct 1997 | A |
5680633 | Koenck et al. | Oct 1997 | A |
5724361 | Fiedler | Mar 1998 | A |
5732346 | Lazaridis et al. | Mar 1998 | A |
5740366 | Mahany et al. | Apr 1998 | A |
5744366 | Kricka et al. | Apr 1998 | A |
5767699 | Bosnyak et al. | Jun 1998 | A |
5796727 | Harrison et al. | Aug 1998 | A |
5798658 | Werking | Aug 1998 | A |
5821809 | Boerstler et al. | Oct 1998 | A |
5839051 | Grimmett et al. | Nov 1998 | A |
5877642 | Takahashi | Mar 1999 | A |
5892382 | Ueda et al. | Apr 1999 | A |
5903176 | Westgate | May 1999 | A |
5905386 | Gerson | May 1999 | A |
5940771 | Gollnick et al. | Aug 1999 | A |
5945847 | Ransijn | Aug 1999 | A |
5945858 | Sato | Aug 1999 | A |
5945863 | Coy | Aug 1999 | A |
5969556 | Hayakawa | Oct 1999 | A |
6002279 | Evans et al. | Dec 1999 | A |
6014041 | Somasekhar et al. | Jan 2000 | A |
6014705 | Koenck et al. | Jan 2000 | A |
6028454 | Elmasry et al. | Feb 2000 | A |
6037841 | Tanji et al. | Mar 2000 | A |
6037842 | Bryan et al. | Mar 2000 | A |
6038254 | Ferraiolo et al. | Mar 2000 | A |
6061747 | Ducaroir et al. | May 2000 | A |
6081162 | Johnson | Jun 2000 | A |
6094074 | Chi et al. | Jul 2000 | A |
6104214 | Ueda et al. | Aug 2000 | A |
6114843 | Olah | Sep 2000 | A |
6188339 | Hasegawa | Feb 2001 | B1 |
6194950 | Kibar et al. | Feb 2001 | B1 |
6222380 | Gerowitz et al. | Apr 2001 | B1 |
6232844 | Talaga, Jr. | May 2001 | B1 |
6259312 | Murtojarvi | Jul 2001 | B1 |
6265898 | Bellaouar | Jul 2001 | B1 |
6310501 | Yamashita | Oct 2001 | B1 |
6340899 | Green | Jan 2002 | B1 |
6374311 | Mahany et al. | Apr 2002 | B1 |
6424194 | Hairapetian | Jul 2002 | B1 |
6463092 | Kim et al. | Oct 2002 | B1 |
Number | Date | Country |
---|---|---|
0 685 933 | Dec 1995 | EP |
0 685 933 | Dec 1995 | EP |
63-280517 | Nov 1988 | JP |
Number | Date | Country | |
---|---|---|---|
20030122603 A1 | Jul 2003 | US |
Number | Date | Country | |
---|---|---|---|
60184703 | Feb 2000 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 09965235 | Sep 2001 | US |
Child | 10315473 | US | |
Parent | 09610905 | Jul 2000 | US |
Child | 09965235 | US |