JP2000242362A - Input/output phase adjusting method and lsi circuit equipped with its function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make variance in input/output phase small even under a min condition and a max condition and to make the phase margin of an inter-LSI interface large by providing a delay condition judgement part which judges a signal delay condition by itself and selecting delay values. SOLUTION: This circuit is composed of input phase matching parts 2 which are connected to input terminals for system signals such as a system clock, a timing signal, and a data signal inputted to an LSI internal circuit, output phase matching parts 3 which are connected to system signal output terminals of the LSI internal circuit 1, and a delay condition judgement part 4. The delay condition judgement part 4 judges the delay condition under which an LSI itself is operating and outputs a delay value switching control signal 5, which is supplied to all the input phase matching parts 2 and all the output phase matching parts 3. Those phase matching parts 2 and 3 select delay values with the delay value switching control signal 5 outputted by the judgement part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital LSI.
The present invention relates to an input / output phase adjustment method for controlling a delay of data input / output timing and an LSI circuit having the function.

[0002]

2. Description of the Related Art In general electronic components as well as LSIs, characteristics such as voltage and delay time of manufactured components vary depending on ambient temperature during use, power supply voltage, manufacturing conditions, and the like. A range is defined, and usually the minimum to minimum characteristic value, the maximum to maximum characteristic value, and the standard characteristic value in the range are described in a characteristic table or the like.

With respect to the transmission delay time of the LSI pulse, the condition that minimizes the delay is called the min condition, which is defined as a condition in which the ambient temperature during use is the lowest temperature in the recommended operating temperature range and the power supply voltage. Are used at the maximum voltage within the recommended voltage range, and the conditions at the time when this LSI is manufactured, that is, the signal transmission of the p-channel and n-channel transistors, which are affected by the device process conditions, have the fastest characteristics. Created when conditions overlap.
Conversely, the max condition is a condition in which the delay time is maximized, and a condition in which the ambient temperature is maximized, the power supply voltage is minimized, and the condition that the signal transmission of the transistor constituting the transistor is the slowest due to the manufacturing conditions is overlapped. Refers to the case. A normal case is used at normal temperature and a standard power supply voltage value, and signal transmission of a device due to manufacturing conditions is also represented as a type condition in a standard case.

Normally, in order for an interface for data transfer between LSIs to be performed normally, it is necessary to satisfy the interface specifications under both a maximum delay condition (max condition) and a minimum delay condition (min condition). Therefore, the input / output of the LSI has a function for adjusting the phase.

The phase adjustment at the interface of the input / output of the LSI generally involves adjusting the phase between the input terminal and the first-stage flip-flop or between the last-stage flip-flop and the output terminal of the LSI.
At the time of LSI design, one fixed delay circuit having a delay value set in advance is inserted and added, whereby phase adjustment between clock and input data and phase adjustment between clock and output data are performed. . Since there is a large difference between the delay value under the min condition and the delay value under the max condition, the delay circuit generally has a delay time sufficient to satisfy the input / output standard under both the min condition and the max condition. Is given.

In recent years, the speed of interfaces between LSIs has been increased, and the standards for input / output phases required for LSI elements have become strict. However, in the above-described conventional phase adjustment method, the margin of the phase relationship that can be interfaced between the LSIs is small because the variation values of the min condition and the max condition received and output by the LSI are still large, and the speed of the interface is increased. Hindered.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is
It is an object of the present invention to provide a technique for reducing variations in input / output phases and increasing a phase margin of an interface between LSIs even under the n condition and the max condition.

[0008]

According to the present invention, there is provided a method for adjusting an input / output phase, which comprises a delay circuit for adjusting an input / output phase.
The input / output phase adjustment unit of the SI further includes a delay condition determination unit for self-determining a signal delay condition, and a plurality of delay values of the delay circuit of the input / output phase adjustment unit are selected based on the determination result of the delay condition determination unit. It is characterized by doing.

Further, an LSI circuit having an input / output phase adjusting function according to the present invention has an input phase matching section connected to a plurality of signal input terminals of the LSI circuit and a plurality of signal output terminals of the LSI circuit. An output phase matching unit and a single delay condition determination circuit, wherein the delay condition determination circuit determines a delay condition in which the LSI itself is operating from an input signal signal dedicated to the delay condition determination unit, and switches a delay value. A control signal is output to all the input phase matching units and all the output phase matching units, and the input and output phase matching units switch delay values according to a delay value switching control signal output from the delay condition determination circuit. It is characterized by.

Further, an LSI circuit having an input / output phase adjusting function according to the present invention has an input phase matching section connected to a plurality of signal input terminals of the LSI circuit and a plurality of signal output terminals of the LSI circuit. An output phase matching unit; and a single delay condition determining unit, wherein the delay condition determining unit determines a delay condition under which the LSI itself operates from one of a plurality of input signals input to the input phase matching unit. And outputs a delay value switching control signal to all of the input phase matching units and all of the output phase matching units, and the input and output phase matching units output delay value switching control signals of the delay condition determining unit. An LSI circuit having an input / output phase adjustment function, wherein a delay value is switched.

Further, the delay condition judging section of the LSI circuit having the input / output phase adjusting function according to the present invention includes a flip-flop circuit and a delay circuit, and the flip-flop circuit outputs an input signal to the delay condition judging section. And outputting the delay value switching control signal from the input signal and a delay signal obtained by transmitting the input signal through the delay circuit.

Another delay condition judging section of the LSI circuit having the input / output phase adjusting function of the present invention includes a flip-flop circuit, a delay circuit, an inhibit signal generation circuit,
An ND circuit, wherein the flip-flop circuit generates a delay signal, wherein an input signal to the delay condition determination unit is transmitted through the delay circuit, and an input signal to the delay condition determination unit and the inhibit signal to generate the inhibit signal. A signal obtained by ANDing a signal transmitted through a circuit and an AND signal is used as an input signal, and the delay value switching control signal is used as an output signal.

Further, the input and output phase matching section of the LSI circuit having the input / output phase adjusting function of the present invention includes a plurality of delay circuits for delaying an input signal and a signal transmitted through the plurality of delay circuits. And a selector circuit for switching and outputting one of them based on the delay value switching control signal output from the delay condition determination unit.

Further, the delay condition judging section and the input / output phase matching section of the LSI circuit having the input / output phase adjustment function of the present invention are configured using primitive cells prepared as function blocks. It is characterized by.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of an LSI circuit having an input / output phase adjusting function according to a first embodiment of the present invention.
This circuit is connected to a plurality of input phase matching units 2 connected to input terminals of system signals such as a system clock, a timing signal, and a data signal input to the LSI internal circuit 1 and to a system signal output terminal of the LSI internal circuit 1. A plurality of output phase matching sections 3 and a delay condition determination section 4. The delay condition judging unit 4 judges a delay condition in which the LSI itself operates, and outputs a delay value switching control signal 5. This output signal is transmitted to all the input phase matching units 2 and all the output phase matching units 3. Supplied to In the input / output phase matching section,
The selection of the delay value is determined by the delay value switching control signal 5 output from the delay condition determination unit 4. The number of input / output phase matching units is equal to the number of signal input / output terminals of the LSI requiring phase matching, and the delay condition determination unit 4 has one in common.

As shown in FIG. 2, the delay condition determination unit 4
It comprises a delay circuit 11 and a flip-flop circuit 10. An input signal dedicated to the delay condition determination unit, which is an external input, is supplied to a C input of the flip-flop circuit 10 and a D input through a delay circuit 11 having an appropriate delay value. Specifically, in the case of the max condition,
A delay value of about one half cycle to less than one cycle of the signal pulse cycle is set and created at the time of designing this LSI.
The output Q of the flip-flop circuit 10 is output as the delay value switching control signal 5.

The input and output phase matching units 2 and 3
As shown in FIG. 3, it is composed of a delay circuit A21, a delay circuit B22 and a selector circuit 20. The system signal inputs are a delay circuit A21 and a delay circuit B having different delay values.
22, the output of the delay circuit A21 is connected to the first input IN1 of the selector circuit 20, the output of the delay circuit B22 is connected to the second input IN2 of the selector circuit 20, and the output of the selector circuit 20 is connected to the phase. The output from this block is output to the output terminal as the adjusted output. The delay value switching control signal 5 received by the selector circuit 20 is supplied from the output of the delay condition determination unit 4 shown in FIG.

When this block is used for input phase matching, as shown in FIG. 1, a system signal input from the outside of the LSI is connected to an input terminal, and an output of the flip-flop ( (Not shown). When used for output phase matching, connect the output from the LSI internal circuit 1 to the input terminal,
The output is connected to an output terminal for outputting a system signal to the outside of the LSI.

The delay values of the delay circuits A21 and B22 of the input / output phase matching section need to be adjusted differently for each of the LSI input / output terminals. It is built differently.

Next, the operation of the first embodiment will be described. The delay condition determination unit 4 performs an operation as shown in the timing chart of FIG. As described above, the delay set value of the delay circuit 11 is set to a delay value in a range from a half cycle of the signal pulse cycle to less than one cycle in which the logic is not inverted under the max condition. FIG. 4A shows the operation when the condition is close to the min condition. The flip-flop (F / F) circuit fetches data at the rising edge of the delay condition determination unit input signal. Delay circuit 1
Since the delay value of 1 is not delayed by a half cycle under the min condition, the output of the flip-flop circuit becomes “0”, and the delay value switching control signal output outputs a low level. When the condition is close to the max condition (FIG. 4B), the delay value of the delay circuit 11 is ma.
Under the x condition, since the delay is more than a half cycle, the output of the flip-flop circuit becomes “1”, and the delay value switching control signal outputs a high level.

In the input / output phase matching unit which receives the delay value switching control signal 5 from the delay condition determination unit 4, the delay circuit A21 having a delay value set to satisfy the phase from the type condition to the max condition. And min from the type condition
One of the delay circuits B22 having a delay value set so as to satisfy the phase under the condition is selected by the selector circuit 20 based on the value (low or high) of the delay value switching control signal output.
And outputs a signal.

Thus, even under the max condition, the min
Even under the conditions, the phase states of all the input / output signals of the LSI can be almost aligned.

FIG. 5 shows the configuration of the second embodiment of the present invention. The basic configuration is the same as that of the first embodiment, but the input of the delay condition determination unit 4 is further devised. In the first embodiment, a signal dedicated to the delay condition determination unit 4 is used as an input signal. However, in this embodiment, an input is not prepared as a dedicated signal for the delay condition determination unit, and one of the normal system signals is not prepared. For example, a system clock or a timing signal having a fixed period is branched and used.

As described above, in the present embodiment, it is not necessary to provide a terminal of the LSI element exclusively for inputting the delay condition judging unit as the LSI, so that the effect of reducing the number of terminals can be obtained.

In the first and second embodiments, the pulse is constantly supplied to the input of the delay condition determination unit. However, this is not always necessary, and the pulse may be stopped after the determination.

FIG. 6 shows an example in which a delay condition judging unit for stopping the pulse after the judgment is formed by adding an inhibit signal generation circuit 31 (INH signal generation circuit) and an AND circuit 32. In the figure, the INH signal generation circuit 31 generates a signal for stopping the C input of the flip-flop circuit 10 after two pulses are input to the input signal. For this reason, once the judgment is made, the judgment result is fixed. Therefore, unnecessary operation of the flip-flop circuit 10 can be prevented.

In the present invention, it is not necessary to develop the delay condition judging section and the input / output phase matching section as dedicated circuits, and it is sufficient to use primitive cells prepared as function blocks.

[0029]

According to the present invention, a circuit (delay condition determining section) for self-determining the operating condition of the LSI is provided in the input / output phase adjustment portion of the LSI, and the input / output phase matching is determined based on the determination result. The delay value is switched by the LSI itself.

For this reason, normal delay variation under the min condition and the max condition can be absorbed, the input and output phases can be easily adjusted, and the effect of increasing the input and output phase margin can be obtained.

[Brief description of the drawings]

FIG. 1 is an example of an LSI circuit configuration having an input / output phase adjustment function according to a first embodiment of the present invention.

FIG. 2 shows an LSI having an input / output phase adjustment function according to the present invention.
9 is an embodiment of a delay condition determination unit forming a circuit.

FIG. 3 is a configuration example of an input / output phase matching unit constituting the first embodiment of the present invention.

FIG. 4 is a timing chart showing an operation of a delay condition determination unit constituting the first embodiment of the present invention.

FIG. 5 is a configuration example of an LSI circuit having an input / output phase adjustment function according to a second embodiment of the present invention.

FIG. 6 shows an LSI having an input / output phase adjustment function according to the present invention.
9 is another embodiment of the delay condition determination unit constituting the circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 LSI internal circuit 2 input phase matching unit 3 output phase matching unit 4 delay condition determination unit 5 delay value switching control signal 10 flip-flop circuit 11 delay circuit 20 selector circuit 21 delay circuit A 22 delay circuit B 31 inhibit signal generation circuit 32 AND circuit

Claims (7)

[Claims] 1. An input / output phase adjusting unit of an LSI having a delay circuit for input / output phase matching further includes a delay condition determining unit for self-determining a signal delay condition. An input / output phase adjustment method comprising selecting a plurality of delay values of a delay circuit of a writing output phase matching unit. 2. An input phase matching unit connected to a plurality of signal input terminals of an LSI circuit, an output phase matching unit connected to a plurality of signal output terminals of the LSI circuit, and a single delay condition determining unit. The delay condition determining unit determines a delay condition in which the LSI itself is operating from an input signal dedicated to the delay condition determining unit, and outputs a delay value switching control signal to all of the input phase matching units and all of the output signals. An LSI circuit having an input / output phase adjustment function, wherein the delay value is switched by a delay value switching control signal output from the delay condition determination unit, the delay value being output to a phase matching unit. 3. An input phase matching unit connected to a plurality of signal input terminals of the LSI circuit, a plurality of output phase matching units connected to a plurality of signal output terminals of the LSI circuit, and a single delay condition determining unit The delay condition determination unit determines a delay condition under which the LSI itself is operating from one of a plurality of input signals input to the input phase matching unit, and outputs a delay value switching control signal to all of the input signals. The input / output phase matching unit outputs a phase matching unit and all the output phase matching units, and the input and output phase matching units switch delay values according to a delay value switching control signal output from the delay condition determination unit. An LSI circuit having an adjustment function. 4. The delay condition judging section includes a flip-flop circuit and a delay circuit, and the flip-flop circuit inputs an input signal to the delay condition judging section and a delay signal that passes the input signal through the delay circuit. The LS having the input / output phase adjustment function according to claim 2 or 3, wherein the delay value switching control signal is output from the following.
I circuit. 5. The delay condition determining section includes a flip-flop circuit, a delay circuit, an inhibit signal generation circuit, and an AND signal.
A delay signal, wherein the flip-flop circuit allows an input signal to the delay condition determination unit to pass through the delay circuit, and an input signal to the delay condition determination unit and the input signal to the inhibit signal generation circuit. A with the signal transmitted through
The LSI circuit having an input / output phase adjustment function according to claim 2 or 3, wherein a signal obtained by taking ND is used as an input signal, and the delay value switching control signal is used as an output signal. 6. The input and output phase matching section,
A plurality of delay circuits for delaying an input signal and a selector circuit for switching and outputting one of signals transmitted through the plurality of delay circuits based on the delay value switching control signal output from the delay condition determination unit. 4. An LSI circuit having an input / output phase adjustment function according to claim 2 or claim 3. 7. The apparatus according to claim 2, wherein the delay condition determination unit and the input / output phase matching unit are configured using primitive cells prepared as function blocks. An LSI circuit having an input / output phase adjustment function.