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US 6,388,493 B2Granted
Clock control method and circuit
AssigneeNEC Corporation
InventorTakanori Saeki
Life of this patent
Estimating the term…
Abstract
A clock control circuit for reducing jitter has at least one averaging circuit for generating, and outputting from an output terminal, a signal having a time difference obtained by internally dividing a time difference between first and second signals input respectively from first and second input terminals. First and second clock signals are supplied respectively to the first and second input terminals of the timing averaging circuit, and a clock in which a time difference between pulses of the first and second clock signals is averaged is generated.
Claims25
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time;
- (c) a second delay circuit chain capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (d) a clock driver outputting the internal clock from an output of said second delay circuit chain;
- and
- (e) a timing averaging circuit, to which are input a clock signal from an input buffer and a signal obtained by passing an internal clock signal, which is output via said clock driver, through an input buffer dummy circuit having a delay time equivalent to that of said input buffer, to generate and output a signal having a time difference obtained by internally dividing, at a prescribed ratio, a time difference between the two signals;
- (f) wherein said first delay circuit chain is supplied with the output of said timing averaging circuit via a dummy delay circuit.
4 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time;
- (c) a second delay circuit chain capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (d) a clock driver outputting the internal clock from an output of said second delay circuit;
- and
- (e) first and second timing averaging circuits, to which are input a clock signal from an input buffer and a signal obtained by passing an internal clock signal, which is output via said clock driver, through an input buffer dummy circuit having a delay time equivalent to that of said input buffer, to generate and output a signal having a time difference obtained by internally dividing, at a prescribed ratio, a time difference between the two signals;
- (f) wherein said first delay circuit chain is supplied with the output of said first timing averaging circuit via a dummy delay circuit, and
- (g) wherein the output of said second timing averaging circuit is supplied as a control signal for controlling transfer of a signal from said first delay circuit chain to said second delay circuit chain.
5 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) two sets of delay circuit chains each of which includes:
- (b1) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time, and
- (b2) a second delay circuit chain capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit;
- and
- (c) first and second timing averaging circuits, to which are input a clock signal from an input buffer and a signal obtained by passing an internal clock signal, which is output via a clock driver, through an input buffer dummy circuit having a delay time equivalent to that of said input buffer, to generate and output a signal having a time difference obtained by internally dividing, at a prescribed ratio, a time difference between the two signals,
- (d) wherein said first delay circuit chain of each set is supplied with the output of said first timing averaging circuit via a dummy delay circuit,
- (e) wherein a frequency-divided signal obtained by frequency dividing the output of said second timing averaging circuit by a frequency divider circuit is supplied as a control signal for controlling-transfer of a signal from said first delay circuit chain of each set to said second delay circuit, and
- (f) wherein an output from a changeover stage of alternately changing over between outputs of said second delay circuits of each of the sets is supplied to the clock driver and output from said clock driver as the internal clock.
6 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising
- (a) a synchronous delay circuit chain which includes:
- (b) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time;
- (c) a second delay circuit chain capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (d) a monitor signal generating circuit for outputting a monitor signal for a period of time over which a clock pulse travels through an input buffer dummy circuit, which is equivalent to an input buffer to which the external clock is input, and a clock driver;
- and
- (e) a timing averaging circuit, to which are input a clock signal from said input buffer and a signal obtained by passing an internal clock signal, which is output via said clock driver, through said input buffer dummy circuit, to generate a signal having a time difference obtained by internally dividing a time difference between these two signals, and outputting this signal to said first delay circuit chain;
- (f) wherein travel of said pulse or pulse edge is halted in said first delay circuit chain while the monitor signal is being output.
4 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time;
- (c) a second delay circuit chain, to which a signal from said first delay circuit chain is input, capable of passing a pulse or pulse edge along a length thereof proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (d) a monitor signal generating circuit outputting a monitor signal, said monitor signal is generated for a period of time over which a clock pulse travels through an input buffer dummy, which is equivalent to an input buffer and a clock driver;
- (e) first and second timing averaging circuits, to which are input a clock signal from said input buffer and an output from said input buffer dummy obtained by passage therethrough of an internal clock signal output via the clock driver, for generating a signal having a time difference obtained by internally dividing a time difference between these signals, and outputting this signal to said first delay circuit chain;
- (f) wherein said first delay circuit chain is supplied with the output of said first timing averaging circuit,
- (g) wherein the output of said second timing averaging circuit is used as a signal for controlling transfer of the clock signal from said first delay circuit chain to said second delay circuit chain, and
- (h) wherein travel of-said pulse or pulse edge is halted in said first delay circuit chain while the monitor signal is being output;
- and
- (l) a changeover circuit changing over between the output of said second delay circuit and the output of said input buffer, to supply the output to said clock driver.
7 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) two sets at delay circuits each of which includes:
- (b1) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time, and
- (b2) a second delay circuit chain, to which a signal from said first delay circuit chain is input, capable of passing a pulse or pulse edge along a length thereof proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (c) first and second timing averaging circuits, to which are input a clock signal from an input buffer and a signal obtained by passing an internal clock signal, which is output via said clock driver, through an input buffer dummy circuit having a delay time equivalent to that of said input buffer, to generate and output a signal having a time difference obtained by internally dividing, at a prescribed ratio, a time difference between the two signals, said first delay circuit chain being supplied with the output of said first timing averaging circuit via a dummy delay circuit;
- (d) a frequency divider circuit frequency dividing outputs from said first and second timing averaging circuits;
- (e) wherein signals obtained by frequency dividing the outputs of said first and second timing averaging circuits by said frequency divider circuit are used as signals for controlling transfer of a clock signal from the first delay circuit chain of each set to said second delay circuit chain;
- (f) a first changeover circuit alternately changing over between outputs of said second delay circuits of each of the sets every clock cycle;
- and
- (g) a second changeover circuit for selecting the output of said input buffer or the output of said first changeover circuit, to supply the output to said clock driver.
7 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time;
- (c) a second delay circuit chain, to which a signal from said first delay circuit chain is input, capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (d) a monitor signal generating circuit outputting a monitor signal for a period of time over which a clock pulse travels through an input buffer dummy, which is equivalent to an input buffer, and a clock driver;
- (e) first and second timing averaging circuits, to which are input a clock signal from said input buffer and a signal obtained by passing an internal clock signal, which is output via the clock driver, through said input buffer dummy circuit, to generate a signal having a time difference obtained by internally dividing, at a prescribed ratio, a time difference between these two signals, and to output this signal to said first delay circuit chain;
- (f) a first changeover circuit selecting the output of said input buffer or the output of said first timing averaging circuit;
- to supply the output to said first delay circuit chain;
- and
- (g) a second changeover circuit changing-over between the output of said first changeover circuit and the output of said second delay circuit chain;
- (h) wherein the output of said second timing averaging circuit and the output of said second changeover circuit are connected to said monitor signal generating circuit, and travel of said pulse or pulse edge is halted in said first delay circuit while the monitor signal is being output.
7 more elements
A clock control circuit of a semiconductor integrated circuit to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time;
- (c) a second delay circuit chain, to which a signal from said first delay circuit chain is input, capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (d) a monitor signal generating circuit outputting a monitor signal, said monitor signal is generated for a period of time over which a clock pulse travels through an input buffer dummy, which is equivalent to an input buffer and a clock driver;
- (e) first, second and third timing averaging circuits, to which are input a clock signal from said input buffer and a signal obtained by passing an internal clock signal, which is output via the clock driver, through said input buffer dummy circuit, to output a signal having a time difference obtained by internally dividing a time difference between the two signals;
- (f) wherein the output of said first timing averaging circuit is input to said first delay circuit chain;
- (g) wherein the output of said second timing averaging circuit is used as a signal for controlling transfer of the clock signal from said first delay circuit chain to said second delay circuit chain;
- and
- (h) wherein the output of said third timing averaging circuit is connected to said monitor signal generating circuit;
- and
- (i) a changeover circuit changing-over between the output of said second delay circuit and the output of said input buffer;
- (j) wherein travel of said pulse or pulse edge is halted in said first delay circuit chain while the monitor signal is being output.
9 more elements
A clock control circuit of a semiconductor integrated circuit device to which an external clock is input for generating an internal clock, comprising:
- (a) a synchronous delay circuit which includes:
- (b) two sets of delay circuit chains each of which includes:
- (b1) a first delay circuit chain through which a pulse or pulse edge is caused to travel for a fixed period of time, and
- (b2) a second delay circuit chain capable of passing a pulse or pulse edge along a length thereof equal or proportional to the length along which the pulse or pulse edge traveled through said first delay circuit chain;
- (c) a timing averaging circuit, to which two input signals are applied, internally dividing at a prescribed ratio, a time difference between said two input signals;
- (d) a monitor signal generating circuit for outputting a monitor signal, said monitor signal is generated for a period of time over which a clock pulse travels through an input buffer dummy, which is equivalent to an input buffer and a clock driver;
- (e) the output of said input buffer being input to a frequency divider circuit;
- (f) the output of said input buffer being delivered as the internal clock via a first changeover circuit and being input to a second frequency divider and said monitor signal generating circuit via said input buffer dummy;
- (g) the frequency-divided output of said frequency divider circuit being supplied to said first delay circuit chain of each of the sets and being supplied as a signal for controlling transfer from said first delay circuit chain of each set to said second delay circuit chain;
- and
- (h) a second changeover circuit changing-over between outputs from the second delay circuit chains of each set;
- (i) wherein the output of said second changeover circuit and the output of said input buffer are supplied to said first changeover circuit.
9 more elements
Dependencies are inferred from the claim text.