Switched capacitor charge sharing technique for integrated circuit devices enabling signal generation of disparate selected signal values

The present invention relates, in general, to the field of semiconductor integrated circuit devices. More particularly, the present invention relates to a switched capacitor charge sharing technique for integrated circuit devices enabling signal generation of disparate selected signal values.

Charge sharing techniques have previously been employed in integrated circuit designs in order to save operating power. A typical circuit example is one utilized in conjunction with dynamic random access memory (DRAM) array bitlines which are precharged to a level of VCC/2 then driven to VCC (supply voltage level) or VSS (circuit ground) for the bit line (BL) and complementary bit line bar (/BL or BLB) depending on the state of the previously stored data.

Other contemporary circuit examples include the use of three groups of logic gates operating at three different voltage ranges. In operation, one group will transition from VCC/3 to VSS, the second group from 2VCC/3 to VCC/3 and the third group from VCC to 2VCC/3. In this manner, these three groups of logic gates can charge share with their adjacent voltage range group, but conventional designs are constrained to operate in this manner. Stated another way, with current circuit techniques the low level of signal or circuit block A is set equal to the high level of the adjacent signal or circuit block B.

What is desired then, is the provision of a charge sharing technique that allows for selected signal, or operating, levels without concern for the number of circuit blocks used to share the charge. In other words, it would highly advantageous to provide, for example, two circuit blocks that can charge share with each other but have VCC/10 operating levels. That is, one signal or block could operate in the range of VCC to 0.9VCC while another signal or block operates between VSS to 0.1 VCC with the two signal generators charge sharing with each other.

The technique of the present invention overcomes the limitations of existing charge sharing circuit techniques by allowing for efficient charge sharing and signal level generation of exact desired values, and wherein the signal levels of the circuits sharing the charge do not have to have the same voltage levels.

In a particular embodiment of the technique of the present invention disclosed herein, a switched capacitor is used to share charge between two different signals, (e.g. alternating current (AC) signals) or two different groups of signals. The size of the capacitor can be adjusted to obtain the required signal level of the various signals. The smaller the capacitor, the smaller the signal level. As the capacitor approaches an infinite number of farads, the signal levels approach the level of VCC/2. If the capacitor is approximately the capacitance of the signal lines, the signal levels are then approximately VCC/3.

One particular method of implementing the technique of the present invention is to precharge a signal line to each side of a capacitor on every other precharge cycle. A second signal line is precharged to the opposite side of this capacitor to the first signal line and is charged every other cycle as well.

Particularly disclosed herein is a charge sharing method which comprises providing a capacitor having first and second terminals thereof, firstly coupling a first signal line to the first terminal of the capacitor and coupling a second signal line to the second terminal of the capacitor, firstly decoupling the first and second signal lines from the first and second terminals of the capacitor respectively, secondly coupling the first signal line to the second terminal of the capacitor and coupling the second signal line to the first terminal of the capacitor, secondly decoupling the first and second signal lines from the second and first terminals of the capacitor respectively and repeating the process of firstly coupling, firstly decoupling, secondly coupling and secondly decoupling.

Also particularly disclosed herein is a charge sharing circuit for first and second pairs of complementary signal lines which comprises a capacitor coupled between first and second circuit nodes, a first input circuit having an output coupled to a first one of the first pair of complementary signal lines, with the first input circuit being coupled between a supply voltage source and a second one of the first pairs of complementary signal lines. A second input circuit has an output coupled to the second one of the first pair of complementary signal lines, with the first input circuit being coupled between the supply voltage source and the first circuit node. A first switching device selectively couples the first one of the first pair of complementary signal lines to the first circuit node and a third input circuit has an output coupled to a first one of the second pair of complementary signal lines, with the third input circuit being coupled between a reference voltage level and a second one of the second pair of complementary signal lines. A fourth input circuit has an output coupled to the second one of the second pair of complementary signal lines, with the fourth input circuit being coupled between the reference voltage level and the second circuit node. A first output circuit is coupled to the first and second ones of the first pair of complementary signal lines and the second circuit node and a second output circuit is coupled to the first and second ones of the second pair of complementary signal lines and the first circuit node. A second switching device selectively couples the first one of the second pair of complementary signal lines to the second circuit node.

Further particularly disclosed herein is a charge sharing circuit for first and second pairs of complementary signal lines which comprises a capacitor coupled between first and second circuit nodes and a first circuit coupled between a supply voltage source and a reference voltage level and coupled to first ones of the first and second pairs of complementary signal lines and the first circuit node. A second circuit is coupled between the supply voltage source and the reference voltage level and is coupled to second ones of the first and second pairs of complementary signal lines and the second circuit node. A third circuit is coupled between the first ones of the first and second pairs of complementary signal lines and to the second circuit node and a fourth circuit is coupled between the second ones of the first and second pairs of complementary signal lines and to the first circuit node.

Still further particularly disclosed herein is a data read driver for an integrated circuit memory array which comprises a first transistor responsive to a data read signal for coupling a supply voltage to a local data read line, a second transistor responsive to a global clock signal for coupling a reference voltage level to a global data read line and a charge sharing circuit coupled between the local data read line and the global data read line.

The aforementioned and other features and objects of the present invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of a preferred embodiment taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a representative data read, global data read driver circuit in accordance with an implementation of the technique of the present invention;

FIG. 2 is a series of waveforms produced by the circuit 100 of the preceding figure illustrating the signals on the complementary global data read (GDR and GDRB) and local data read (DR and DRB) lines with a capacitance Ceq=10 fF;

FIG. 3 is an additional series of waveforms produced by the circuit 100 of FIG. 1 illustrating the signals on the complementary GDR, GDRB, DR and DRB lines with a capacitance Ceq=25 fF;

FIG. 4 is a further series of waveforms produced by the circuit 100 of FIG. 1 illustrating the signals on the complementary GDR, GDRB, DR and DRB lines with a capacitance Ceq=250 fF;

FIG. 5 is a final series of waveforms produced by the circuit 100 of FIG. 1 illustrating, in descending order, the signals on the PREB, PRE2B, PRE2, PRE1B, PRE1, PRE, GDRLB, GDRL, DRLB and DRL lines with a capacitance Ceq=10 fF;

FIG. 6 is a schematic illustration of another embodiment of a representative data read, global data read driver circuit in accordance with an implementation of the technique of the present invention;

FIG. 7 is a series of waveforms produced by the circuit 200 of the preceding figure illustrating, in descending order, the signals on the DRL, DRLB, PRE, GDRL, GDRLB, GPREB, HCLK an HCLKB lines with capacitors C 3 and C 6 having a capacitance of 12 fF;

FIG. 8 is an additional series of waveforms produced by the circuit 200 of FIG. 6 illustrating the signals on the GDR, GDRB, DR and DRB lines for values of capacitors C 3 and C 6 of 12 fF;

FIG. 9 is a further series of waveforms produced by the circuit 200 of FIG. 6 illustrating the signals on the GDR, GDRB, DR and DRB lines for values of capacitors C 3 and C 6 of 2 fF;

FIG. 10 is a schematic illustration of yet another embodiment of a representative data read, global data read driver circuit in accordance with an implementation of the technique of the present invention;

FIG. 11 is a simplified series of waveforms illustrating the signals on the complementary data read (DR, DRB) and global data read (GDR, GDRB) lines in accordance with the technique of the present invention as the former transition between VCC and VCC −0.1V and the latter transition between VSS (0V) and 0.1V;

FIG. 12 is a schematic illustration of still another embodiment of a representative data read, global data read driver circuit in accordance with an implementation of the technique of the present invention;

FIG. 13 is a simplified series of waveforms produced by the circuit 500 of the preceding figure illustrating the signals on the VEQ1, VEQ2, PRE11B, PRE22B, DRLB, DR, PRE1, PRE2, GCLK and GDR lines; and

FIG. 14 is a simplified schematic illustration of yet another embodiment of a switched capacitance, charge sharing circuit in accordance with the technique of the present invention.

With reference now to FIG. 1 , a schematic illustration of a representative data read, global data read driver circuit 100 in accordance with an implementation of the technique of the present invention is shown.

The circuit 100 comprises, in pertinent part, a capacitor 102 (Ceq) coupled between nodes EQ 1 and EQ 2 . The circuit 100 further comprises series connected P-channel transistors 104 and 106 having the signals DRL and PREB respectively coupled to their gate terminals. Series connected P-channel transistors 108 and 110 are also provided coupled between a supply voltage source (VCC) and the node EQ 1 and have the signals DRLB and PRE 1 B respectively coupled to their gate terminals. Transistors 104 and 106 are coupled between VCC and the node intermediate transistors 108 and 110 which is denominated DR. The node intermediate transistors 104 and 106 is denominated DRB.

P-channel transistor 112 is coupled between node DRB and node EQ 1 and receives the signal PRE 1 B at its gate terminal, while P-channel transistor 114 is coupled between node DR and node EQ 2 . P-channel transistor 116 is coupled between node DRB and node EQ 2 as shown. The gate terminals of transistors 114 and 116 commonly receive the PRE2B signal.

Similarly, the circuit 100 comprises series connected N-channel transistors 122 and 124 having the signals PRE and GDRL respectively coupled to their gate terminals. Series connected N-channel transistors 118 and 120 are also provided coupled between a reference voltage source (VSS) and the node EQ 2 and have the signals PRE 1 and GDRLB respectively coupled to their gate terminals. Transistors 122 and 124 are coupled between VSS and the node intermediate transistors 118 and 120 which is denominated GDR. The node intermediate transistors 122 and 124 is denominated GDRB.

N-channel transistor 126 is coupled between node GDRB and node EQ 2 and receives the signal PRE 1 at its gate terminal, while N-channel transistor 128 is coupled between node GDR and node EQ 1 . N-channel transistor 130 is coupled between node GDRB and node EQ 1 as shown. The gate terminals of transistors 128 and 130 commonly receive the PRE2 signal. A capacitance of 250 fF appears on the local and global data read lines DR/DRB and GDR/GDRB as shown.

With reference additionally now to FIG. 2 , a series of waveforms produced by the circuit 100 of the preceding figure is shown illustrating the signals on the complementary global data read (GDR and GDRB) and local data read (DR and DRB) lines. In this illustration, capacitor 102 has a capacitance of Ceq=10 fF. At the top of the figure, the DR and DRB lines are shown to transition between substantially 1.0 volts to 1.0 volts minus 100 millivolts while at the bottom of the figure, the GDR an GDRB lines are shown to transition between substantially 0.0 volts and 100 millivolts.

With reference additionally now to FIG. 3 , an additional series of waveforms produced by the circuit 100 of FIG. 1 is shown illustrating the signals on the complementary GDR, GDRB, DR and DRB lines. In this illustration, capacitor 102 has a capacitance of Ceq=25 fF. In this configuration, the DR and DRB lines at the top are shown to transition between substantially 1.0 volts to 1.0 volts minus 150 millivolts while at the bottom of the figure, the GDR an GDRB lines are shown to transition between substantially 0.0 volts and 150 millivolts.

With reference additionally now to FIG. 4 , a further series of waveforms produced by the circuit 100 of FIG. 1 is shown illustrating the signals on the complementary GDR, GDRB, DR and DRB lines. In this illustration, capacitor 102 has a capacitance of Ceq=250 fF. In this configuration, the DR and DRB lines at the top are shown to transition between substantially 1.0 volts to 1.0 volts minus 300 millivolts while at the bottom of the figure, the GDR an GDRB lines are shown to transition between substantially 0.0 volts and 300 millivolts.

With reference additionally now to FIG. 5 , a final series of waveforms produced by the circuit 100 of FIG. 1 is shown illustrating, in descending order, the signals on the PREB, PRE2B, PRE2, PRE1B, PRE1, PRE, GDRLB, GDRL, DRLB and DRL lines. In this illustration, capacitor 102 has a capacitance of Ceq=10 fF.

With reference additionally now to FIG. 6 , a schematic illustration of another embodiment of a representative data read, global data read driver circuit 200 in accordance with an implementation of the technique of the present invention is shown. The circuit 200 comprises, in pertinent part, charge sharing circuitry 202 as shown. The charge sharing circuitry comprises P-channel transistor 204 in series with N-channel transistor 206 and having their common connected gate terminals coupled to receive an HCLKB signal. The node intermediate transistors 204 and 206 is connected to one terminal of capacitor 208 (C 3 ) while the other terminal is coupled to the node intermediate P-channel transistor 210 and N-channel transistor 212 which are coupled between voltage sources VDH and VDL as shown. The source terminals of transistors 204 , 210 , 214 and 220 are all coupled to VDH while the source terminals of transistors 206 , 212 , 216 and 222 are all coupled to VDL.

In like manner, P-channel transistor 214 and series connected N-channel transistor 216 are also coupled between VDH and VDL. The gate terminals of transistors 210 , 212 , 214 and 216 are coupled together to receive the HCLK signal. The node intermediate transistors 214 and 216 is coupled to one terminal of capacitor 218 (C 6 ) which has its other terminal coupled to the node intermediate series connected P-channel transistor 220 and N-channel transistor 222 which have their common connected gate terminals receiving the HCLKB signal.

Series connected P-channel transistors 224 and 226 , with their gate terminals respectively receiving the GDRLB an GPREB signals, couple VCC to the source terminal of transistor 204 while series connected N-channel transistors 236 and 238 , with their gate terminals respectively receiving the PRE and DRLB signals, couple VSS to the source terminal of transistor 206 . Similarly, series connected P-channel transistors 232 and 234 , with their gate terminals respectively receiving the GDRL an GPREB signals, couple VCC to the source terminal of transistor 220 while series connected N-channel transistors 244 and 246 , with their gate terminals respectively receiving the PRE an DRL signals, couple VSS to the source terminal of transistor 222 . The node intermediate transistors 224 and 226 defines the GDR line while the node intermediate transistors 232 and 234 defines the GDRB line. Correspondingly, the node intermediate transistors 236 and 238 defines the DR line while the node intermediate transistors 244 and 246 defines the DRB line. A capacitance of substantially 250 fF couples the GDR, GDRB, DR and DRB lines to circuit ground as shown.

With reference additionally now to FIG. 7 , a series of waveforms produced by the circuit 200 of the preceding figure is shown illustrating, in descending order, the signals on the DRL, DRLB, PRE, GDRL, GDRLB, GPREB, HCLK an HCLKB lines. In this illustration, capacitors C 3 and C 6 have a capacitance of 12 fF.

With reference additionally now to FIG. 8 , an additional series of waveforms produced by the circuit 200 of FIG. 6 is shown illustrating the signals on the GDR, GDRB, DR and DRB lines for values of capacitors C 3 and C 6 of substantially 12 fF. At the top of the figure, the GDR and GDRB lines are shown to transition between substantially 1.0 volts to 1.0 volts minus 220 millivolts while at the bottom of the figure, the DR an DRB lines are shown to transition between substantially 0.0 volts and 220 millivolts.

With reference additionally now to FIG. 9 , a further series of waveforms produced by the circuit 200 of FIG. 6 is shown illustrating the signals on the GDR, GDRB, DR and DRB lines for values of capacitors C 3 and C 6 of substantially 2 fF. Again at the top of the figure, the GDR and GDRB lines are shown to transition between substantially 1.0 volts to 1.0 volts minus 125 millivolts while at the bottom of the figure, the DR an DRB lines are shown to transition between substantially 0.0 volts and 125 millivolts.

With reference additionally now to FIG. 10 , a schematic illustration of yet another embodiment of a representative data read, global data read driver circuit 300 in accordance with an implementation of the technique of the present invention is shown. The circuit 300 comprises, in pertinent part a capacitor 302 (in this embodiment substantially 6 fF) coupled between nodes EQ 1 and EQ 2 .

Series connected P-channel transistors 304 and 306 , having the signals DRLB and PRE 1 B respectively coupled to their gate terminals, couple VCC to the node EQ 1 . The node intermediate the transistors 304 and 306 defines line DR. Further, series connected N-channel transistors 318 and 320 , having the signals PRE 2 and GDRLB respectively coupled to their gate terminals, couple VSS to the node EQ 1 . The node intermediate the transistors 318 and 320 defines line GDR. P-channel transistor 308 , having its gate terminal coupled to receive the PRE2B signal, couples the DR line to node EQ 2 which, in turn, is coupled to the GDR line through N-channel transistor 322 which has its gate terminal coupled to receive the PRE1 signal.

In like manner, series connected P-channel transistors 312 and 314 , having the signals DRL and PRE 2 B respectively coupled to their gate terminals, couple VCC to the node EQ 21 . The node intermediate the transistors 312 and 314 defines line DRB. Further, series connected N-channel transistors 326 and 328 , having the signals PRE 1 and GDRL respectively coupled to their gate terminals, couple VSS to the node EQ 2 . The node intermediate the transistors 326 and 328 defines line GDRB. P-channel transistor 316 , having its gate terminal coupled to receive the PRE1B signal, couples the DRB line to node EQ 1 which, in turn, is coupled to the GDRB line through N-channel transistor 330 which has its gate terminal coupled to receive the PRE2 signal.

In this particular embodiment as illustrated, the DR line is coupled directly to the DRB line while the GDR line is also coupled directly to the GDRB line as shown. A capacitance of substantially 250 fF couples the DR, DRB, GDR and GDRB lines to circuit ground while the EQ1 and EQ2 lines are coupled to circuit ground through a capacitance of substantially 2 fF.

With reference additionally now to FIG. 11 , a simplified series of waveforms is shown illustrating the signals on the complementary data read (DR, DRB) and global data read (GDR, GDRB) lines in accordance with the technique of the present invention as the former transition between VCC and VCC −0.1V and the latter transition between VSS (0V) and 0.1V.

With reference additionally now to FIG. 12 , a schematic illustration of still another embodiment of a representative data read, global data read driver circuit 500 in accordance with an implementation of the technique of the present invention is shown. The circuit 500 comprises a capacitor 502 (Ceq) coupled between nodes VEQ1 and VEQ2 as shown.

The circuit 500 further comprises a P-channel transistor 504 coupled between VCC and the DR line, with its gate terminal coupled to receive the DRLB signal. A P-channel transistor 506 couples the DR line to the VEQ1 node and has its gate terminal coupled to receive the PRE11B signal. Another P-channel transistor 508 couples the DR line to the VEQ2 node and has its gate terminal coupled to receive the PRE22B signal.

An N-channel transistor 510 couples the VEQ1 node to the GDR line and has its gate terminal coupled to receive the PRE2 signal. Another N-channel transistor 512 couples the VEQ2 node to the GDR line and has its gate terminal coupled to receive the PRE1 signal. An additional N-channel transistor 514 couples the GDR line to circuit ground and has its gate terminal coupled to receive the GCLK signal. As illustrated, in this embodiment of the present invention, the DR line transitions substantially between VCC and VCC −100 millivolts while the GDR line transitions between VSS and 100 millivolts. A parasitic capacitance couples the DR and GDR lines to circuit ground as indicated.

With reference additionally now to FIG. 13 , a simplified series of waveforms produced by the circuit 500 of the preceding figure is shown illustrating the signals on the VEQ1, VEQ2, PRE11B, PRE22B, DRLB, DR, PRE1, PRE2, GCLK and GDR lines.

As can be seen, the PRE11B signal activates transistor 506 substantially concurrently with the PRE1 signal activating transistor 512 while transistors 508 and 510 are not activated. In like manner, when transistors 506 and 512 are not activated, the PRE22B signal activates transistor 508 substantially concurrently with the PRE2 signal activating transistor 510 . The DLRB signal activates transistor 504 at substantially the same time that the GCLK signal activates transistor 514 .

With reference additionally now to FIG. 14 , a simplified schematic illustration of yet another embodiment of a switched capacitance, charge sharing circuit 600 in accordance with the technique of the present invention is shown. The circuit 600 comprises a capacitor 602 which has one terminal thereof coupled to a terminal of transistor 608 and 614 and another terminal thereof coupled to a terminal of transistors 610 and 612 . The gate terminals of transistors 608 and 610 receive a signal φ 1 having a first phase while the gate terminals of transistors 612 and 614 receive a signal φ 2 having a differing phase. The remaining terminals of transistors 608 and 612 are coupled to a first circuit block 604 while the remaining terminals of transistors 610 and 614 are coupled to circuit block 606 . The circuit block 604 is coupled, for example, to a supply voltage source VCC for receiving a current i 1 while the circuit block 606 is coupled to circuit ground (or VSS) and having a current therethrough indicated as i 2 .

While there have been described above the principles of the present invention in conjunction with specific circuit implementations, capacitances and voltage ranges, it is to be clearly understood that the foregoing description is made only by way of example and not as a limitation to the scope of the invention. Particularly, it is recognized that the teachings of the foregoing disclosure will suggest other modifications to those persons skilled in the relevant art. Such modifications may involve other features which are already known per se and which may be used instead of or in addition to features already described herein. Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure herein also includes any novel feature or any novel combination of features disclosed either explicitly or implicitly or any generalization or modification thereof which would be apparent to persons skilled in the relevant art, whether or not such relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as confronted by the present invention. The applicants hereby reserve the right to formulate new claims to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a recitation of certain elements does not necessarily include only those elements but may include other elements not expressly recited or inherent to such process, method, article or apparatus. None of the description in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope and THE SCOPE OF THE PATENTED SUBJECT MATTER IS DEFINED ONLY BY THE CLAIMS AS ALLOWED. Moreover, none of the appended claims are intended to invoke paragraph six of 35 U.S.C. Sect. 112 unless the exact phrase “means for” is employed and is followed by a participle.