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GTK - TDC analysis. Lukas Perktold 17 th March 2010. Progress. Layout vs Schematic ► Parasitic extraction Corner Simulation ► Check basic functionally of circuit ? check Loop Dynamics. ERROR identified - TDC runs at 320 MHz. Delay Line – Sakari vs Mine. Delay depends on - PowerPoint PPT Presentation
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GTK - TDC analysis
Lukas Perktold
17th March 2010
Progress
Layout vs Schematic
► Parasitic extraction Corner Simulation
► Check basic functionally of circuit
? check Loop Dynamics
ERROR identified
-
TDC runs at 320 MHz
Delay Line – Sakari vs Mine• Delay depends on
RFN_min: fixed at 506.9 mV (50 uA)
RFN: adjusted by the Loop
• difference in delay curve (Sakari vs Mine)• may used different methods? (bias current, measurement)• rather big difference between different corners
TDC – Current Cons.
TDC in locked state -> delay = 97 ps
+
• Biasing: 75.8 uA• SEtoDE: 56.9 uA• CP: 622 uA• PD: 80 uA
peak: 665 uA• Counters: 537 uA
peak: 4 mA
• Coarse HRs: 100 uA x2• PG Bank: off
= 33.6 mA
• 65 % of the current consumption due to the “8x buffer”• high peak current for digital parts of TDC
Delay Line – Supply Distribution
MQ wire: 350u x 3u
R□ = 33.9 mOhmReff = 2x 4 Ohm
Ieff = 33.4 mA
Vdrop = 2x 133.6 mV
TDC – Operating Point
• Different power domains for TDC and Biasing-Current• Loop locks at 320 MHz with new operating point out of Reset
• TOP level wiring only rough estimate• separated power domains in simulation (several)
New Operating Point:
VDDD = 1.5 V
RCLK_Bias = 250 uA RFN = 588.5 mV (to VDSS)
Delay Line - Measurement
• simulation and measurements differ (Corners? / inaccurate model?)
Thanks to Matthew for the plot RCLK_Bias = 250 uA RFN = 750 mV
• match simulation to measurements
• move to new DK version
• make a list of all errors found through measurements
• check if the all errors can be explained (might have more errors in the design)
- Weak performance (e.g. INL) of the TDC for rising edges - Zero dies out for higher frequencies - compare RFN settling values - ...
• propose solution to errors found and document them
Outline
TDC – Operating Point – 250uA