A 0.6V 205MHz 19.5ns tRC 16Mb Embedded DRAM VLSI Systems I A 0.6V 205MHz 19.5ns tRC 16Mb Embedded...
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Transcript of A 0.6V 205MHz 19.5ns tRC 16Mb Embedded DRAM VLSI Systems I A 0.6V 205MHz 19.5ns tRC 16Mb Embedded...
A 0.6V 205MHz 19.5ns tRC 16Mb Embedded DRAM
VLSI Systems I
A 0.6V 205MHz 19.5ns tRC 16Mb
Embedded DRAMK. Hardee, F. Jones, D. Butler, M.
Parris, M. Mound, H. Calendar, G. Jones, L. Aldrich, C.
Gruenschlaeger, M. Miyabayashi, K. Taniguchi, T. Arakawa
A 0.6V 205MHz 19.5ns tRC 16Mb Embedded DRAM
VLSI Systems I
Overview
• Primary use– Embedded DRAM
• Uniqueness claim– Ultra-low supply voltage (0.6V) for low power consumption
• Difficulties of low voltage operation– Reduced transistor thresholds cause greater off current
– At low voltages, circuit speed is more dependent on manufacturing variations
– Low voltages make bitline sensing more difficult
A 0.6V 205MHz 19.5ns tRC 16Mb Embedded DRAM
VLSI Systems I
Overview (continued)
• Solution #1– Current through reference transistor is monitored and body bias
is regulated to increase Vt during quiescent periods
– Improves speed for slow process conditions by 63%
– Reduces leakage current by 75%
• Solution #2– A sleep mode is introduced that further reduces leakage current
• Solution #3– Extra low Vt (0.2V) transistors are used to provide low-voltage
sensing for bitlines
A 0.6V 205MHz 19.5ns tRC 16Mb Embedded DRAM
VLSI Systems I
Detailed Specifications
Size 16Mb
Power Supply 0.7V & 2.5V
Cell Size 0.195um2
Cell Capacitance 40fF
Bitline Bias Vcc/2 = .35V
Maximum Refresh Time 128ms
Maximum Cells / Row 128
Interface / Clocking SDR
External IO Voltage 3.0V
Number of Banks 4