Clock Networks and PLLs in Altera’s Stratix III Devices

1. Clock Networks and PLLs in Altera’s Stratix III Devices VLSI Systems I Fall 2007 Hamid Abbaalizadeh

2. 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.

3. Global and Regional Clock network and Clock Control Blocks

4. PPLs in Stratix III • Up to 12 PLLs that provides robust clock management

5. 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.

6. 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

7. PLLs Features