RECONFIGURABLE SWITCHED-CAPACITOR VOLTAGE CONVERTER CIRCUIT, INTEGRATED CIRCUIT (IC) CHIP INCLUDING THE CIRCUIT AND METHOD OF SWITCHING VOLTAGE ON CHIP
A configurable-voltage converter circuit that may be CMOS and an integrated circuit chip including the converter circuit and method of operating the IC chip and circuit. A transistor totem, e.g., of 6 or more field effect transistors, PFETs and NFETs, connected (PNPNPN) between a first supply (Vin) line and a supply return line. A first switching capacitor is connected between first and second pairs of totem PN FETs pair of transistors. A second switching capacitor is connected between the second and a third pair of totem FETs. A configuration control selectively switches both third FETs off to float the connected end of the second capacitor, thereby switching voltage converter modes.
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The present invention is related to voltage conversion techniques and, more particularly, to switched capacitor voltage converters and methods for use in integrated circuit devices.
BACKGROUND DESCRIPTIONEspecially for complex Integrated Circuit (IC) chips and IC chips with arrays with a large number of devices, device leakages can overwhelm chip power be. A general application of leakage reduction techniques impairs performance and has been equally unpalatable. Accordingly, some designs use multiple supplies or a variable supply to selectively reduce supply voltage, e.g., supply one voltage during memory access and a second, lower voltage when memory cells are not being accessed.
Thus, some higher performance chips use on-chip voltage converters, e.g., switched-capacitor circuits, to reduce higher chip supply voltages to a level suitable for high performance circuit operation. State of the art switched-capacitor circuits inherently enable very high efficiency for ratioed conversion. For example, a 2:1 down conversion (0.5) has demonstrated at 90% efficiency. Such a voltage converter enables much higher supply voltage delivery to the chip for powering lower voltage circuit, e.g., providing a 2.0V supply to the chip may be converted down to 1.0V on-chip for 1V circuits. Linear regulators, which have been used for voltage conversion at ratios above 0.5, also achieve >90% efficiency for conversion at the higher performance end of the output voltage range, e.g., 1.3V to >1.2V conversion. However, efficiency falls off dramatically at the lower end of the output voltage range, e.g., ˜50% for 1.3V->0.7V conversion and below.
Thus, there is a need for a high efficiency voltage converter for on-chip voltage conversion that provides uniform efficiency across a wide conversion range; and more particularly, a variable conversion ratio on-chip voltage converter, and especially a variable voltage switched-capacitor converter, that exhibits a high efficiency even at the lower end of the voltage conversion range.
SUMMARY OF THE INVENTIONA feature of the invention is improved power efficiency in down converting on-chip supply voltages;
Another feature of the invention is a switchable voltage supply, supplying low-voltage performance circuits with a reduced chip voltage;
Yet another feature of the invention is reduced chip supply switching noise;
Yet another feature of the invention is a switchable voltage supply, supplying low-voltage performance circuits with a reduced chip voltage, while improving power convertion efficiency and chip supply switching noise.
The present invention relates to a configurable-voltage converter circuit that may be CMOS and an integrated circuit chip including the converter circuit and method of operating the IC chip and circuit. A transistor totem, e.g., of 6 or more field effect transistors, PFETs and NFETs, connected (PNPNPN) between a first supply (Vin) line and a supply return line. A first switching capacitor is connected between first and second pairs of totem PN FETs pair of transistors. A second switching capacitor is connected between the second and a third pair of totem FETs. A configuration control selectively switches both third FETs off to float the connected end of the second capacitor, thereby switching voltage converter modes.
Embodiments of the invention include:
A method of configuring on-chip supply voltage being supplied to one or more chip circuits, said method comprising: selecting a first voltage supply mode; floating one side of a first capacitor in a pair of series connected capacitors, the other side of said first capacitor being connected to a first side of a second capacitor of the series connected pair; alternately switching opposite sides of said second capacitor to a voltage supply output (Vout), one side of said second capacitor being alternately switched between a first supply voltage and said voltage supply output, the other side of said second capacitor being alternately switched between a second supply voltage and said voltage supply output, said voltage supply output supplying a first output voltage; selecting a second voltage supply mode; alternately floating and coupling said one side of said first capacitor to said first supply voltage and simultaneously switching the other side of said second capacitor to said voltage supply output when said one side is floating, said first side of said second capacitor being alternately switched in and out to said voltage supply output, the other side of said second capacitor being alternately switched between said second supply voltage and said voltage supply output, said voltage supply output supplying a second output voltage; and waiting to reselect said first voltage supply mode.
In this embodiment in said first voltage supply mode alternately switching said opposite sides comprises: floating one side of a first capacitor in a pair of series connected capacitors, the other side of said first capacitor being connected to a first side of a second capacitor of the series connected pair; asserting a first clock; coupling said first side of said second capacitor to said first supply voltage responsive to said first clock; coupling the other side of said second capacitor to said supply voltage output responsive to said first clock; asserting a second clock, said first clock and said second clock not overlapping; coupling said first side of said second capacitor to said supply voltage output responsive to said second clock; coupling the other side of said second capacitor to said second supply voltage responsive to said second clock; and returning to asserting said first clock.
In said second voltage supply mode alternately floating and coupling said one side and alternately switching said opposite sides comprises: asserting said first clock; coupling said one side of said first capacitor to said first supply voltage responsive to said first clock; coupling said other side of said second capacitor to said voltage supply output responsive to said first clock; asserting a second clock, said one side of said second capacitor being floated; coupling said other side of a said first capacitor to said voltage supply output responsive to said second clock; coupling said other side of said second capacitor to said second supply voltage responsive to said second clock; and returning to asserting said first clock. The first capacitor may be connected between a pair of FETs and floating said one side of said first capacitor comprises gating both FETs off. Floating said one side of said first capacitor further comprises gating on an FET shorting the opposite ends of both off FETs. The chip may be a CMOS chip, where said pair of FETs is a PFET and an NFET in a FET totem including alternate PFETs and NFETs; said other side of said first capacitor and said first side of a second capacitor of the series connected capacitor pair being connected between a second PN FET pair; and said other side of said second capacitor being connected between a second PN FET pair. Asserting said first clock may turn on totem PFETs with asserting said second clock turning on totem NFETs, the first PN FET pair being gated by said first clock and said second clock when said second mode is selected. The second supply voltage may be a supply return for said first supply voltage (Vin).
Another embodiment is a method of configuring on-chip supply voltage being supplied to one or more chip circuits, said method comprising: selecting a first voltage supply mode; floating one side of a first capacitor in a pair of series connected capacitors, the other side of said first capacitor being connected to a first side of a second capacitor of the series connected pair; and while said first voltage supply mode is selected, asserting a first clock; coupling said first side of said second capacitor to a first voltage supply line responsive to said first clock; coupling the other side of said second capacitor to an on-chip supply voltage output (Vout) responsive to said first clock; asserting a second clock, said first clock and said second clock not overlapping; coupling said first side of said second capacitor to said on-chip supply voltage output responsive to said second clock; coupling the other side of said second capacitor to a second voltage supply line responsive to said second clock; and returning to assert said first clock.
This embodiment further comprises: selecting a second voltage supply mode; and while said second voltage supply mode is selected, asserting said first clock; coupling said one side of said first capacitor to said first voltage supply line responsive to said first clock; coupling said other side of said second capacitor to said on-chip supply voltage output responsive to said first clock; asserting a second clock; coupling said one side of a said first capacitor to said on-chip supply voltage output responsive to said second clock; coupling said other side of said second capacitor to said second voltage supply line responsive to said second clock; and returning to assert said first clock. The first voltage supply mode may be a 2:1 configuration mode, said second voltage supply mode may be a 3:1 configuration mode and upon a next selection of said 2:1 mode, said method further comprising returning to float said one side of said first capacitor. The first capacitor is connected between a pair of FETs and floating said one side of said first capacitor comprises gating both FETs off. One of said first voltage supply line and said second voltage supply line may be a supply return line and the other may be a chip supply (Vin), floating said one side of said first capacitor further comprises gating on an FET shorting the opposite ends of both off FETs, and Vin:Vout may be selectable as 2:1 or 3:1. The chip may be a CMOS chip, with said pair of FETs being a PFET and an NFET in a FET totem including alternate PFETs and NFETs; said other side of said first capacitor and said first side of a second capacitor of the series connected capacitor pair being connected between a second PN FET pair; and said other side of said second capacitor being connected between a second PN FET pair. Asserting said first clock turns on totem PFETs and asserting said second clock turns on totem NFETs, the first PN FET pair being gated by said first clock and said second clock when said second mode is selected. The second supply voltage line may be said supply return for said first supply voltage line (Vin).
Another embodiment is a method of configuring on-chip supply voltage being supplied to one or more CMOS chip circuits, said method comprising: selecting a first voltage supply mode; floating one side of a first capacitor in a pair of series connected capacitors connected to a field effect transistor (FET) totem connected between a first supply (V1) and a second supply (V2), the other side of said first capacitor being connected to a first side of a second capacitor of the series connected pair, said one side being connected between a first PFET and NFET (PN FET) totem pair, said other side and said first side being connected between a second PN FET totem pair and the opposite side of said second capacitor being connected between a third PN FET totem pair; alternately turning PFETs off and on and NFETs on and off in the second and third PN FET totem pair, said second and third PN FET totem pairs alternately switching opposite sides of said second capacitor to a voltage supply output (Vout); selecting a second voltage supply mode; alternately turning PFETs off and on and NFETs on and off in the first, second and third PN FET totem pairs, said first PN FET totem pair alternately floating and coupling said one side of said first capacitor to V1, and said second and third PN FET totem pairs simultaneously alternately switching said other side of said second capacitor to Vout when said one side is floating, said second and third PN FET totem pairs alternately switching opposite sides of said second capacitor to Vout; and waiting to reselect said first voltage supply mode.
In this embodiment in said first voltage supply mode, alternately switching said opposite sides may comprise: in a first half cycle PFETs in both said the second and third PN FET totem pair being switched on, said PFET in said second PN FET totem pair switching said first side of said second capacitor to V1, and said PFET in said third PN FET totem pair switching said opposite side of said second capacitor to Vout, the corresponding NFETs in both pair being off; and in a second half cycle by switching PFETs off and NFETs on, on NFETs switching said first side of said second capacitor to Vout and said other side of said second capacitor to V2. Floating one side in said first voltage supply mode may comprise: shorting said first PN FET pair; and holding off both the PFET and NFET in said first PN FET pair, said first side being connected between said PFET and NFET. V1 may be Vin, V2 may be ground and shorting said first PN FET pair comprises turning on a shunting PFET in parallel with said first PN FET pair.
Alternately switching said opposite sides in said first voltage supply mode may comprise: asserting a PFET clock low, an NFET clock being low while said PFET clock is asserted, said PFET in said second PN FET pair coupling said first side of said second capacitor to one side of said shunt PFET, said PFET in said third PN FET pair coupling said other side of said second capacitor to said Vout; driving said PFET clock high; asserting said NFET clock high, said NFET in said second PN FET pair coupling said first side of said second capacitor to Vout, said NFET in said third PN FET pair coupling the other side of said second capacitor to said supply return; driving said NFET clock low; and returning to asserting said PFET clock low. Alternately floating and coupling said one side of said first capacitor in said second voltage supply mode may comprise: turning said shunting PFET off; and passing said PFET clock through a PFET clock gate to the gate of said PFET in said first PN FET pair and said NFET through an NFET clock gate to the gate of said NFET in said first PN FET pair. V1 may be ground, V2 may be Vin, shorting said first PN FET pair comprises turning on a shunting NPFET in parallel with said first PN FET pair, and Vin:Vout may be selectable as 2:1 in said first voltage supply mode or 3:1 in said second voltage supply mode.
Yet another embodiment is a method of configuring on-chip supply voltage being supplied to one or more CMOS chip circuits, said method comprising: asserting a configuration select in a first state, said first state selecting a first voltage supply mode; turning a shunting field effect transistor (FET) on, said shunting FET shorting a first PFET and NFET pair (PN FET pair) in a FET totem connected between a first supply voltage (V1) and a second supply voltage (V2), one side of a first capacitor in a pair of series connected capacitors connected between the PFET and NFET in said first PN FET pair; blocking a PFET clock and an NFET clock to said first PN FET pair, both the PFET and NFET in said first PN FET pair being held off, said one side of said first capacitor floating; switching on PFETs in said the second and third PN FET totem pair in a first half cycle, said PFET in said second PN FET totem pair switching said first side of said second capacitor to V1, and said PFET in said third PN FET totem pair switching the opposite side of said second capacitor to Vout, the corresponding NFETs in both pair being off; switching said PFETs off in a second half cycle and NFETs on, on NFETs switching said first side of said second capacitor to Vout and said other side of said second capacitor to V2; returning to switching on PFETs until said configuration select is asserted in a second state, and when asserted in said second state a second voltage supply mode has been selected; and then turning off said shunting FET; passing said PFET clock and said NFET clock to said first PN FET pair, both the PFET and NFET in said first PN FET pair being gated on by a respective clock; switching on PFETs in the first, second and third PN FET totem pairs in a first half cycle, said PFET in said first PN FET totem pair switching said one side of said first capacitor to V1, and said PFET in said third PN FET totem pair switching the opposite side of said second capacitor to Vout, the corresponding NFETs in said first, second and third PN FET totem pairs being off; switching said PFETs off in a second half cycle and NFETs on, on NFETs switching said first side of said second capacitor to Vout and said other side of said second capacitor to V1; and returning to switching on PFETs in all three PN FET totem pairs until said first voltage supply mode is reselected. V1 may be Vin, V1 may be ground, and Vin:Vout may be selectable as 2:1 in said first voltage supply mode or 3:1 in said second voltage supply mode.
The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which:
Semiconductor technology and chip manufacturing advances have resulted in a steady decrease of chip feature size to increase on-chip circuit switching frequency (circuit performance) and the number of transistors (circuit density). Density has increased as a result of shrinking/reducing overall device or field effect transistor (FET) size by reducing feature sizes and, correspondingly, device minimum dimensions. A typical shrink includes horizontal dimensions (e.g., minimum channel length) and vertical dimensions, e.g., channel layer depth, gate dielectric thickness, junction depths and etc. Smaller device features have improved device performance and reduced device operating conditions, i.e., chip and correspondingly, device supply voltages and voltage swings.
Generally, all other factors being constant, the active power consumed by a given logic unit increases linearly with switching frequency (f), i.e., with performance. Also, higher operating frequency requires higher current (I) to switch loads faster. Thus, not withstanding the decrease of chip supply voltage (V), chip power (P=VI) consumption has increased as well. Both at the chip and system levels, a natural result of this increase in chip power is escalated cooling and packaging costs. For low end systems (e.g., handhelds, portable and mobile systems), where battery life is crucial, reducing net power consumption is important. However, such a power reduction must come without degrading chip/circuit performance below acceptable levels.
To minimize semiconductor circuit power consumption while maximizing performance, most integrated circuits (ICs) are made in the well-known complementary insulated gate FET technology known as CMOS. A typical CMOS circuit includes paired complementary devices, i.e., an n-type FET (NFET) paired with a corresponding p-type FET (PFET), usually gated by the same signal and, typically, driving a capacitive load. Ideally, when the gate of a NFET is below some positive threshold voltage (VT) with respect to its source, the NFET is off, i.e., the switch is open. Above VT, the NFET is on conducting current, i.e., the switch is closed. Similarly, a PFET is off when its gate is above its VT, i.e., less negative, and on below VT.
A CMOS inverter, for example, is a PFET and NFET pair that are series connected between a power supply voltage (Vdd) and ground (GND). Both are gated by the same input and both drive the same output, more or less, a purely capacitive load. The PFET pulls the capacitive load high and the NFET pulls the load low at opposite input signal states. Since the pair of devices have operating characteristics that are, essentially, opposite each other, when one device (e.g., the NFET) is on and conducting (modeled simply as a closed switch), the other device (the PFET) is off, not conducting (ideally modeled as an open switch) and, vice versa. Thus, there is no static or DC current path in an ideal CMOS circuit; ideal CMOS circuits use no static or DC power; and only consume transient power from current charging and discharging capacitive loads. Coincidentally, most noise on chip supply lines is switching noise from transient current switching the loads.
At chip level, supply switching currents through supply line resistances and parasitic inductance can generate significant line noise at the chip power pins and/or pads, e.g., several hundred millivolt (mV) spikes on a one volt (1V) supply line. These current spikes waste power, impair circuit operation, reduce performance, and may cause sporadic errors that are difficult to locate and diagnose. Without changing chip power, chip supply currents can be reduced by increasing chip supply voltage above on-chip operating supply voltage. However, high performance circuits normally operate at maximum tolerable supply voltage, where higher supply voltages may cause permanent circuit damage.
Moreover, in practice, typical FETs are much more complex than switches and transient power for circuit loads accounts for only a portion of CMOS chip power consumption. FET drain to source current (DC current and so, DC power consumed) is dependent upon circuit conditions and device voltages. Especially since device VT is directly proportional to gate dielectric thickness, as FET features (including gate dielectric thickness) shrink, off FETs conduct what is known as subthreshold current, i.e., at gate biases below threshold for NFETs and above for PFETs. Further, for a particular device, subthreshold current increases exponentially with the magnitude of the device's drain to source voltage (Vds) and reduces exponentially with the magnitude of the device's VT. This is especially true in what is known as partially depleted (PD) or fully depleted (FD) silicon on insulator (SOI) technologies, where subthreshold leakage has been shown to increase dramatically, such that it may be the dominant source of leakage. Additional device leakages including gate leakages (i.e., gate to channel, gate to source or drain and gate induced drain leakage (GIDL)) and source/drain junction leakages also contribute to static power.
When multiplied by the millions and even billions of devices on a state of the art SRAM processor cache, for example, even one hundred picoAmps (100 pA) of leakage in each of a eight million cells results in chip leakage on the order of eight hundred milliAmps (800 mA). Thus, as FET features have shrunk, these leakage sources have become more prominent. Generally, approaches to resolving these device problems have been to increase device VT to mitigate subthreshold leakage, or to reduce supply voltage. Especially for complex chips and arrays with a large number of devices, device leakage (both gate and subthreshold) chip leakage power can be overwhelming, but general application of leakage reduction techniques impairs performance and has been equally unpalatable. Accordingly, some designs use multiple supplies or a variable supply to selectively reduce supply voltage, e.g., supply one voltage during memory access and a second, lower voltage when memory cells are not being accessed.
When both Φ and Φ* transition low 60, both NFETs 52N, 54N are off and both PFETs 52P, 54P are on, and the loop/output current (Iload1) 62 is the PFET source to drain current. Since, I=CdV/dt, for a given switching frequency f, dV/dt≈VinΔf and Iload1≈CVinΔf. Similarly, when both Φ and Φ* transition high 64, both PFETs 52P, 54P are off and both NFETs 52N, 54N are on, the loop/output current (Iload2) 66 is the NFET source to drain current, and again, Iload2≈CVinΔf. Thus, at steady state, Iload=Iload1+Iload2≈2CVinΔf, and VC≈Vout=½Vin (1−Δ).
In this example, the configuration control 104 is connected between the supply 102 and an intermediate node 122 at the top PN pair of FETs, 110N, 110P. The configuration control 104, selectively blocks or passes the in-phase non-overlapping phases (Φ, Φ*) to the top PN pair FET, NFET 110N and PFET 110P, depending on whether the configurable-voltage converter circuit 100 is configured 2:1 or 3:1 mode, respectively. A mode select signal (VCONFIG) 124 passes through a level shifter 126 to provide a configuration selection signal (CONFIG) 124′. The preferred configurable-voltage converter circuit 100 provides a single selected output voltage (Vout) at the intermediate node 122 between the bottom two PN FET pairs 106N, 106P and 108N, 108P.
In this example, CONFIG 124, 124′ low selects 2:1 mode (Vin, 102 to Vout 128) or, high selects 3:1 mode. A PFET 130 connected between the supply 102 and the intermediate node 122 is gated by CONFIG 124′. The level shifter 126 passes CONFIG 124′ to a pair of clock select circuits 132, 134. The clock phases (Φ, Φ*) are in phase, but non-overlapping to prevent orthogonalities, where both PFETs 106P, 108P, 110P and NFETs 106N, 108N, 110N are on simultaneously. The NFET phase Φ is asserted high; and the PFET phase Φ* is asserted low. The clock select circuits 132, 134, responsive to CONFIG 124′, pass the respective clock phases (Φ, Φ*) to the gates 136, 138 of the top PN pair of FETs, 110N, 110P.
As can be seen from
The NFET 110N clock gate 134 is substantially similar to the PFET 110P clock gate 132, except that the second NAND gate does not include gate PFET 154P. Thus, when CONFIG 124′ is low, the clock gate 134 output 138 is not pulled high and floats. An inverter 156 (also between the supply 102 and the voltage at intermediate node 122) inverts CONFIG 124′, to drive NFET 158. NFET 158, which is connected between the clock gate 134 output 138 and Vout 128, NORs the second NAND result with CONFIG−, and the result is Φ·CONFIG, with a high signal level at the supply voltage 102 and a low signal level at intermediate voltage 122, when 3:1 mode is selected, and at Vout 128, when 2:1 mode is selected, which pulls the NFET gate below its source to assure that the NFET remains off
Advantageously, a preferred switched-capacitor, configurable-voltage converter circuit provides a low-cost, on-chip, multiple, selectable voltage supply. In particular a preferred converter circuit provides multiple selectable supply voltages from a single, relatively higher voltage for supplying on-chip power to lower voltage circuits. Further, because the lower voltages are capacitively switched from the higher voltage, chip supply switching currents are similarly reduced (3:1 or 2:1) from on-chip switching currents. Thus, the preferred converter circuit provides an efficient low voltage source with dramatically reduced chip level switching currents and associated switching noise.
While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. It is intended that all such variations and modifications fall within the scope of the appended claims. Examples and drawings are, accordingly, to be regarded as illustrative rather than restrictive.
Claims
1. A configurable-voltage converter circuit comprising:
- a transistor totem connected between a first supply (Vin) line and a second supply line;
- a first switching capacitor connected at one end between a first pair of totem transistors and at the opposite end between a second pair of totem transistors;
- a second switching capacitor connected at one end between said second pair of totem transistors and at said opposite end between a third pair of totem transistors;
- a configuration control selectively switching both of said third pair of totem transistors off, said opposite end of said second switching capacitor being isolated when said third pair is switched off; and
- a supply output between one transistor in said first pair of totem transistors and a transistor in said second pair of totem transistors, voltage on said supply output being selected by said configuration control.
2. A configurable-voltage converter circuit as in claim 1, wherein said transistor totem is a plurality of first conduction type transistors alternating with a plurality of second conduction type transistors connected between said first supply (Vin) line and said second supply line, each pair of totem transistors being one of said first conduction type transistors and one of said second conduction type transistors.
3. A configurable-voltage converter circuit as in claim 2, wherein said configuration control comprises a shunt transistor in parallel with said third pair of said totem transistors, and a pair of clock select circuits, said shunt transistor and said pair of clock select circuits being gated by a configuration select signal.
4. A configurable-voltage converter circuit as in claim 3 receiving a pair of non-overlapping clock phases including a first phase gating first conduction type transistors and a second phase gating second conduction type transistors, wherein each phase is an input to one of said pair of clock select circuits, each clock circuit passing a respective phase responsive to said configuration select signal.
5. A configurable-voltage converter circuit as in claim 4, wherein said second supply line is a supply return line, said configurable-voltage converter circuit is a CMOS converter, said first conduction type is N-type and said second conduction type is P-type.
6. A configurable-voltage converter circuit as in claim 5, wherein said pair of clock select circuits comprise a PFET clock select circuit and an NFET clock select circuit passing respective clock phases responsive to said configuration signal being at a first level and blocking said respective clock phases responsive to said configuration signal being at a second level.
7. A configurable-voltage converter circuit as in claim 6, wherein said supply output is at a first supply level when said configuration signal is at said first level, and said supply output is at a second supply level when said configuration signal is at said second level.
8. A configurable-voltage converter circuit as in claim 7, wherein:
- said PFET clock select circuit comprises a pair of NAND gates, the first NAND gate NANDing a PFET clock phase with said configuration signal and said second NAND gate NANDing the output of said first NAND gate with said configuration signal;
- said NFET clock select circuit comprises a NAND gate NANDing an NFET clock phase with said configuration signal, an inverter and an NAND-NOR NANDing the output of said first NAND gate with said configuration signal and NORing the result with an inverted said configuration signal; and
- said configuration signal being high configures said configurable-voltage converter circuit in three to one (3:1) mode and said configuration signal being low configures said configurable-voltage converter circuit in three to one (2:1) mode.
9. A configurable-voltage converter circuit as in claim 5, wherein the PFET of the third PN FET pair is connected at one conduction terminal to said first supply (Vin) line.
10. A configurable-voltage converter circuit as in claim 5, wherein the NFET of the third PN FET pair is connected at one conduction terminal to said first supply return line.
11. A CMOS configurable-voltage converter circuit comprising:
- a field effect transistor (FET) totem of alternate P-type FETs (PFETs) and N-type FETs (NFETs) connected between a first supply (Vin) line and a second supply line;
- a first switching capacitor connected at one end between a first PN pair of totem FETs and at the opposite end between a second PN pair of totem FETs, the first PN pair of FETs and the second PN pair of FETs being gated by a pair of non-overlapping clocks;
- a second switching capacitor connected at one end between said PN second pair of totem FETs and at said opposite end between a third PN pair of totem FETs;
- a configuration control comprising a shunt transistor in parallel with said third pair of said totem transistors gated by a configuration select signal and selectively passing said pair of non-overlapping clocks or switching both of said third PN pair of totem FETs off and said shunt transistor on, said opposite end of said second switching capacitor being isolated when the third PN FET pair is switched off; and
- a supply output between one FET in said first PN pair of totem FETs and an opposite type FET in said second PN pair of totem FETs, voltage on said supply output being selected by said configuration control.
12. A CMOS configurable-voltage converter circuit as in claim 11, wherein said configuration control further comprises a pair of clock select circuits, each being one of a PFET clock select circuit and an NFET clock select circuit, each receiving one phase of said pair of non-overlapping clocks, and each being gated by said configuration select signal.
13. A CMOS configurable-voltage converter circuit as in claim 12, wherein each phase is an input to one of said pair of clock select circuits, each clock circuit passing a respective phase responsive to said configuration select signal.
14. A CMOS configurable-voltage converter circuit as in claim 13, wherein said PFET clock select circuit and said NFET clock select circuit pass respective clock phases responsive to said configuration signal being at a first level and block said respective clock phases responsive to said configuration signal being at a second level, said first level selecting a three to one (3:1) configuration and said second level selecting a two to one (2:1) configuration.
15. A configurable-voltage converter circuit as in claim 14, wherein the PFET of the third PN FET pair is connected at one conduction terminal to said first supply (Vin) line.
16. A configurable-voltage converter circuit as in claim 14, wherein the NFET of the third PN FET pair is connected at one conduction terminal to said second supply line.
17. An CMOS integrated circuit (IC) chip comprising:
- a supply voltage line to an IC chip;
- a supply return line to said IC chip;
- a plurality of circuits on said IC chip, at least one circuit operating at a plurality of voltages lower than said supply voltage;
- a configurable-voltage converter circuit comprising: a field effect transistor (FET) totem of alternate P-type FETs (PFETs) and N-type FETs (NFETs) connected between a first supply line and a second supply line, said first supply line being coupled to Vin and said second supply line being coupled to said supply return line, a first switching capacitor connected at one end between a first PN pair of totem FETs and at the opposite end between a second PN pair of totem FETs, the first PN pair of FETs and the second PN pair of FETs being gated by a pair of non-overlapping clocks, a second switching capacitor connected at one end between said PN second pair of totem FETs and at said opposite end between a third PN pair of totem FETs, a configuration control comprising a shunt transistor in parallel with said third pair of said totem transistors gated by a configuration select signal and selectively passing said pair of non-overlapping clocks or switching both of said third PN pair of totem FETs off and said shunt transistor on, said opposite end of said second switching capacitor being isolated when the third PN FET pair is switched off, and
- a supply output (Vout) between one FET in said first PN pair of totem FETs and an opposite type FET in said second PN pair of totem FETs, voltage on said supply output being selected by said configuration control.
18. A CMOS IC chip as in claim 17, wherein said configuration control further comprises a pair of clock select circuits, each being one of a PFET clock select circuit and an NFET clock select circuit, each receiving one phase of said pair of non-overlapping clocks, and each gated by a configuration select signal.
19. A CMOS IC chip as in claim 18, wherein each phase is an input to one of said pair of clock select circuits, each clock circuit passing a respective phase responsive to said configuration select signal.
20. A CMOS IC chip as in claim 19, wherein said PFET clock select circuit and said NFET clock select circuit pass respective clock phases responsive to said configuration signal being at a first level and block said respective clock phases responsive to said configuration signal being at a second level, said first level selecting a three to one (3:1) configuration and said second level selecting a two to one (2:1) configuration.
21. A CMOS IC chip as in claim 19, wherein the PFET of the third PN FET pair is connected at one conduction terminal to said first supply (Vin) line.
22. A CMOS IC chip as in claim 19, wherein the NFET of the third PN FET pair is connected at one conduction terminal to a supply return line.
23. An CMOS integrated circuit (IC) chip comprising:
- a supply voltage line to an IC chip;
- a supply return line to said IC chip;
- a plurality of circuits on said IC chip, at least one circuit operating at a pair of voltages lower than said supply voltage;
- a configurable-voltage converter circuit, configurable between three to one (3:1) and two to one (2:1) voltage conversion, comprising: a field effect transistor (FET) totem of three P-type FETs (PFETs) and three N-type FETs (NFETs) serially connected alternating P and N FETs between a first supply line and said a second supply line, a first switching capacitor connected at one end between a first PN pair of totem FETs and at the opposite end between a second PN pair of totem FETs, the NFET of said first PN pair being further connected to said second supply line, the first PN pair of FETs and the second PN pair of FETs being gated by a pair of non-overlapping clocks, a second switching capacitor connected at one end between said PN second pair of totem FETs and at said opposite end between a third PN pair of totem FETs, the PFET of said third PN pair being further connected to first supply line, a configuration control gated by a configuration select signal and selectively passing said pair of non-overlapping clocks or switching both of said third PN pair of totem FETs off, said configuration select signal selecting between 3:1 and 2:1, said configuration select signal turning off said third PN FET pair in 2:1 mode, said third PN FET pair being gated by said pair of non-overlapping clocks in 3:1 mode, and a supply output between the PFET in said first PN pair of totem FETs and the NFET in said second PN pair of totem FETs, voltage on said supply output being selected by said configuration control.
24. A CMOS IC chip as in claim 23, wherein said configuration control comprises a shunt PFET in parallel with said third PN pair of said totem FETs, a PFET clock select circuit and an NFET clock select circuit, each receiving one phase of said pair of non-overlapping clocks and each gated by said configuration select signal, said configuration select signal gating said shunt PFET.
25. A CMOS IC chip as in claim 24, wherein said first supply (Vin) line is coupled to said supply voltage line and said second supply line is coupled to said supply return line.
26. A configurable-voltage converter circuit as in claim 1, wherein said configuration control comprises a shunt transistor in parallel with said third pair of said totem transistors, said shunt transistor being gated by a configuration select signal.
Type: Application
Filed: Nov 30, 2012
Publication Date: Jun 5, 2014
Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION (Armonk, NY)
Inventors: Leland Chang (New York, NY), Robert Montoye (Rochester, MN), Jae-sun Seo (White Plains, NY)
Application Number: 13/690,985
International Classification: G05F 3/02 (20060101);