Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Current driver
Reexamination Certificate
2002-07-17
2004-03-30
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Current driver
C327S108000
Reexamination Certificate
active
06714055
ABSTRACT:
Pursuant to 35 U.S.C. 119(a)-(d), this application claims priority from German application no. 101 35 786.9, filed Jul. 23, 2001.
DESCRIPTION
The invention relates to an output driver device for an integrated circuit in accordance with claim
1
and to a method for outputting an output signal from an output driver device in accordance with claim
8
.
Output driver devices (off chip driver, OCD) are used for signal outputting in particular in semiconductor components. The output driver device in this case represents the interface between the integrated circuit and its periphery and must satisfy a multiplicity of specifications with regard to the signal outputting (such as, for example, a suitable edge steepness (slew rate), short-circuit driver strength, access time (t
AC
), hold time (t
OH
) etc.).
Conventional output driver devices suffer from the disadvantage that the number of specifications to be complied with in respect of the signal outputting are often more numerous than the “degrees of freedom” of the output driver device. In order, for example, to set the edge steepness of a signal to be output in a specification-conforming manner, it is usually necessary to make interventions in the output driver device which lead to a multiplicity of undesirable changes to other specifications. This is because, conventionally, complying with required specifications of the output driver device is achieved by suitably altering individual transistor parameters of the output driver device. However, each change in an individual transistor parameter influences the entire switching behavior of the output driver device, as a result of which an iterative approximation with a multiplicity of steps is required in order to satisfy all the specifications.
In view of these disadvantages, it is an object of the invention to specify an output driver device which, in a simple manner, can be coordinated with a multiplicity of specifications to be complied with. Furthermore, it is an object of the invention to specify a corresponding method for outputting an output signal from an output driver device.
This object is achieved according to the invention by means of an output driver device in accordance with claim
1
and a method in accordance with claim
8
. The dependent claims relate to preferred embodiments.
According to the invention, an output driver device for an integrated circuit comprises
at least one output device, which has at least one output terminal for an output signal to be output from the output driver device;
at least one input terminal for an input signal to be input into the output driver device; and
at least one control device, which is signal-connected to the output device and the input terminal and is designed for the transformation of the input signal into at least two mutually different control signals and for the outputting of the control signals via control signal outputs to the output device,
the output device being designed for the generation of the output signal in a manner dependent on the control signals. According to the invention, an additional control device is provided between the output device, which outputs the output signal to an, in particular, external output terminal, and the input terminal of the output driver device. This control device is designed to transform or convert the input signal present at the input terminal—which may also be a node in an integrated circuit—into two mutually different control signals. The output device subsequently generates the output signal in a manner dependent on these at least two control signals.
Since the input signal is thus transformed into two different control signals by the control device and the output signal is generated in a manner dependent on these control signals, the control device provides at least one additional “degree of freedom” for the coordination of the output driver device for satisfying the required specifications in respect of the signal outputting. This is because the control device can preferably be designed such that the control signals differ from the input signal in such a way that a required specification, for example the edge steepness of the output signal, is satisfied. The output driver device preferably comprises a control device which is designed for a transformation of the input signal into a multiplicity (e.g. 4) of mutually different control signals. In this case, three additional degrees of freedom are obtained for the co-ordination of the output driver device.
In accordance with one preferred embodiment of the invention, the control signals and the input signal are binary pulse signals and the control device is designed for a transformation of the input signal such that at least one of the control signals differs from the input signal by at least one relative temporal shift of at least one of the signal edges of the control signal with respect to the corresponding signal edge of the input signal. Consequently, the control device is designed for a time sequence variation of the input signal. In this connection, binary pulse signals are understood to be voltage signals which comprise, in particular, essentially rectangle-like pulses with a lower voltage value (low) and an upper voltage value (high). The control device preferably transforms the input signal in such a way that the input signal differ [sic] from at least one of the control signals by virtue of the temporal position of the rising/falling signal edges of corresponding pulses between input signal and control signal. This makes it possible, for example by means of a predetermined time delay of the signal edges of one of the control signals relative to the input signal, to output such control signals to the output device which serve for more advantageous switching of the output device for the purpose of satisfying the specifications.
In accordance with a further preferred embodiment, the control device is designed for a transformation of the input signal such that rising signal edges of the control signal (i.e. low-high transitions) are time-delayed by a first delay time and falling signal edges of the control signal (i.e. high-low transitions) are time-delayed by a second delay time relative to the corresponding signal edges of the input signal. The first delay time may deviate from the second delay time in this case. Such time control of the control signals according to the invention enables greater flexibility when switching individual transistors of the output device, as a result of which specifications that are to be satisfied by the output driver device can be established more easily.
In accordance with a further preferred embodiment, the control device comprises at least one NOR and at least one NAND gate, whose gate outputs are in each case electrically connected precisely to one of the control signal outputs. The control device comprises at least two inverters whose inverter outputs are in each case electrically connected to a gate input both of the NOR and of the NAND gate and whose inverter inputs are in each case electrically connected to the input terminal. The gates and/or inverters of the control device are chosen in such a way that the control signals generated by the control device differ from one another in particular in terms of their time sequence. By way of example, the first control signal differs from the input signal by virtue of a long time delay of rising signal edges of the control signal relative to the corresponding signal edge of the input signal and an only short time delay in the case of falling signal edges. By contrast, the second control signal could differ from the input signal by virtue of a short time delay in the case of rising signal edges and a long time delay in the case of falling signal edges. The better control thereby obtained over switching instants of the output device (an additional “degree of freedom”) simplifies the satisfying of the required specifications. In order to obtain such time sequence control by the control device, the gates and/or the inverters may differ fr
Fish & Richardson P.C.
Infineon - Technologies AG
Tran Toan
LandOfFree
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