3CMemory-Power Usage

3CMemory
This table gives the current for reading and writing into a 819K DRAM using 3CMemory and a TSMC 0.18um process with scalable CMOS rules.

These estimates were made by carefully considering the CVf (capacitance * voltage * frequency) relationships for all of the active read and write bit lines, CVf relationships for all long or heavily loaded digital traces and adding all significant DC bias currents for the analog blocks.

Memory Type	Read Power Usage Per Bit P	Capacitance C	Voltage Supply Vs	Change in bit line voltage Vbl	Frequency f	Number of bit lines that change	Conditions P = C * Vs * Vbl * f
3T	4.5uW	0.2pF	1.5V	1.5V	10MHz	1	Data dependent; all 1's
1T	4.5uW	0.2pF	1.5V	0.75V	10MHz	2
3CMemory BASE2	0.6uW	0.2pF	1.5V	0.2V	10MHz	1	Data dependent; all 1's With Current Stop
3CMemory BASE4	0.3uW	0.2pF	1.5V	0.2V	10MHz	1	Data dependent; all 1's With Current Stop Two bits per bit cell

3T
The single ended amplifier in the 3T prior art DRAM requires changing only one bit line. The bit line starts at 1.5V and goes to 0V, but is data dependent so change does not occur when the memory value is 0. Assuming worst case scenario with the memory value of 1, the bit line moves 1.5V.

1T
The 1T requires changing both bit lines. The bit lines each start at 0.75V. One bit line moves to 0V and the other bit line moves to 1.5V. Considering both bit lines, the total change in voltage is 1.5V.

3CMemory
Base 2 Mode - 3CMemory requires changing only one bit line. Typically the bit line starts at 1V. With Current Stop the bit line goes to 0.8V, but is data dependent so change does not occur when the memory value is 0. Assuming worst case scenario with the memory value of 1, the bit line moves 0.2V.

Base 4 Mode - Same as Base 2 mode in that it takes 0.2V to perform one read operation. In Base 4 mode each read operation reads 2 bits so the Read Power Usage Per Bit result was divided by 2.

Process um	Mode	Current mA	Conditions
0.18	Continuous Memory Write BASE4	0.55	16 bit words @ 25MHz
0.18	Data Retention BASE4	0.025	Temp. = 27C
0.18	Data Retention BASE4	0.5	Temp. = 85C
0.18	Continuous Memory Read BASE4	0.22	16 bit words @25MHz
0.18	Continuous Memory Read BASE2	0.9	16 bit words @100MHz