Multi-ported memory array utilizing bitcells with balanced P-N diffusion layouts
A memory device includes at least one bitcell coupled to a local bitline. The at least one bitcell includes first, second, and third sets of a plurality of transistor devices. The first set is configured to form at least one write port. The at least one write port receives digital data. The second set of the plurality of transistor devices is configured as an inverter pair that stores the digital data. The third set of the plurality of transistor devices is configured to form at least one read port. The at least one read port is used to access the digital data from the inverter pair and output the digital data on the local bitline. The plurality of transistor devices consists of an equal number of P-channel transistor devices and N-channel transistor devices.
1 . A memory device comprising:
at least one bitcell coupled to a local bitline, the local bitline comprising a plurality of pre-discharge devices, and the at least one bitcell comprising:
a first set of a plurality of transistor devices configured to form at least one write port, the at least one write port to receive digital data;
a second set of the plurality of transistor devices configured as an inverter pair, the inverter pair to store the digital data;
a third set of the plurality of transistor devices configured to form at least one read port, the at least one read port to access the digital data stored at the inverter pair and output the digital data to a node on the local bitline, and the plurality of transistor devices consisting of an equal number of P-channel transistor devices and N-channel transistor devices, wherein the first set and the third set comprise transistor devices of a different type, at least one of the first set or the third set comprises transistor devices with a common gate terminal, and at least one of the plurality of pre-discharge devices pre-discharges the node to a source supply voltage (Vss); and
read merge circuitry coupled to the local bitline, the read merge circuitry comprising a plurality of pre-discharge devices coupled to a corresponding plurality of clipper devices, and the read merge circuitry to:
pre-discharge a node of the local bitline at a first read port of the at least one read port of the bitcell to a source supply voltage (Vss) at a first pre-discharge device of the plurality of pre-discharge devices;
initiate charge sharing between the node of the local bitline and a full swing local bitline node of the read merge circuitry via a first clipper device of the plurality of clipper devices; and
assert a read wordline (RWL) at a read transfer transistor of the bitcell to cause a read operation at the first read port.
2 . The memory device of claim 1 , wherein the plurality of transistor devices consists of four N-channel metal-oxide semiconductor (NMOS) transistors and four P-channel metal-oxide semiconductor (PMOS) transistors.
3 . The memory device of claim 2 , wherein the at least one write port is a single write (1 W) port formed by two PMOS transistors of the four PMOS transistors, the two PMOS transistors having the common gate terminal.
4 . The memory device of claim 3 , wherein the at least one read port comprises two read (2R) ports formed by two of the four NMOS transistors.
5 . The memory device of claim 1 , wherein the P-channel transistor devices and the N-channel transistor devices comprise complementary field-effect transistors (CFETs).
6 . The memory device of claim 1 , wherein the at least one read port is a single read (1R) port formed by at least two of the N-channel transistor devices, the at least one read port configured for a differential read of the digital data stored in the inverter pair.
7 . The memory device of claim 1 , wherein the at least one write port is formed by two of the P-channel transistor devices.
8 . The memory device of claim 7 , wherein gate terminals of the two of the P-channel transistor devices form a write-wordline-bar (wwl_b) terminal associated with writing the digital data into the inverter pair.
9 . The memory device of claim 1 , wherein the at least one bitcell is configured as one of:
an eight-transistor (8T) two read port and one write port (2R1W) bitcell;
an 8T one read port and one write port (1R1W) bitcell, wherein the one read port is configured for a single-ended read operation; and
an 8T 1R1W bitcell, wherein the one read port is configured for a differential read operation.
10 . A memory device comprising:
a plurality of bitcells coupled via a local bitline, each bitcell of the plurality of bitcells comprising at least two read ports; and
read merge circuitry coupled to the local bitline, the read merge circuitry comprising a plurality of pre-discharge devices coupled to a corresponding plurality of clipper devices, and the read merge circuitry to:
pre-discharge a node of the local bitline at a first read port of the at least two read ports of the bitcell to a source supply voltage (Vss) at a first pre-discharge device of the plurality of pre-discharge devices;
initiate charge sharing between the node of the local bitline and a full swing local bitline node of the read merge circuitry via a first clipper device of the plurality of clipper devices; and
assert a read wordline (RWL) at a read transfer transistor of the bitcell to cause a read operation at the first read port.
11 . The memory device of claim 10 , wherein the read merge circuitry further comprises:
a first N-channel metal-oxide semiconductor (NMOS) transistor configured as the first pre-discharge device.
12 . The memory device of claim 11 , wherein the first pre-discharge device is configured to pre-discharge the node of the local bitline based on a clock select high voltage signal asserted at a gate of the first NMOS transistor.
13 . The memory device of claim 11 , wherein the read merge circuitry further comprises:
a P-channel metal-oxide semiconductor (PMOS) transistor configured as a pre-charge device.
14 . The memory device of claim 13 , wherein the pre-charge device is configured to charge the full swing local bitline node of the read merge circuitry before the charge sharing, based on a clock select low voltage signal asserted at a gate of the PMOS transistor.
15 . The memory device of claim 13 , wherein the read merge circuitry further comprises:
a second NMOS transistor configured as the first clipper device.
16 . The memory device of claim 15 , wherein the first clipper device is configured to initiate the charge sharing between the node of the local bitline and the full swing local bitline node of the read merge circuitry based on a clock select high voltage signal asserted at a gate of the second NMOS transistor.
17 . A method for performing a memory access operation, the method comprising:
pre-discharging at a pre-discharge device of a plurality of pre-discharge devices coupled to a corresponding plurality of clipper devices, a node of a local bitline at a first read port of at least two read ports of a bitcell to a source supply voltage (Vss);
initiating a charge sharing between a node of the local bitline and a full swing local bitline node of a read merge circuitry coupled to the local bitline; and
asserting a read wordline (RWL) at a read transfer transistor of the bitcell to cause a read operation at the first read port.
18 . The method of claim 17 , further comprising:
asserting a first clock select high voltage signal at a gate of a first N-channel metal-oxide semiconductor (NMOS) transistor of the read merge circuitry to perform the pre-discharging of the node of the local bitline.
19 . The method of claim 18 , further comprising:
assert a clock select low voltage signal at a gate of a P-channel metal-oxide semiconductor (PMOS) transistor of the read merge circuitry to charge the full swing local bitline node of the read merge circuitry before the charge sharing.
20 . The method of claim 19 , further comprising:
asserting a second clock select high voltage signal at a gate of a second NMOS transistor of the read merge circuitry to initiate the charge sharing between the node of the local bitline and the full swing local bitline node of the read merge circuitry.