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Clock Networks and PLLs in Altera’s Stratix III Devices. VLSI Systems I Fall 2007 Hamid Abbaalizadeh. Clock Resources in Stratix III Devices.
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Clock Networks and PLLs in Altera’s Stratix III Devices VLSI Systems I Fall 2007 Hamid Abbaalizadeh
Clock Resources in Stratix III Devices • Global clocks (GCLKs), Regional Clocks (RCLKs), and Peripheral Clocks (PCLKs) are organized into hierarchical structures that provides 220 unique clock domains. • 16 low skew GCLKs drive functional blocks like DSP and PLL • Maximum of 88 low skew and low delay RCLKs drive logic. • 116 higher skew PCLKs can be used as general purpose routing to drive signals into and out of the device.
PPLs in Stratix III • Up to 12 PLLs that provides robust clock management
De-skewing by PLL • Phase Frequency Detector (PFD) method is used for clock alignments. • Charge Pump (CP) drives the current to Loop Filter (LF) if it receives an up signal. If it gets down signal, CP sinks the current from LF. • Voltage Controlled Oscillator (VCO) is biased by LF. • LF also eliminates the glitches and prevents the overshoot, which the jitter on the VCO.
Features • Maximum internal clock speed 600 MHz • On chip RAM 600 MHz • DSP block speed 550 MHz • PFD method in the PLLs is used to de-skew the clocks