MULTIPLE CLOCK GENERATOR (MCG)

Toric's MCG is a versatile multi-clock generator with GHz capability, targeting complex SoC .

Its innovative approach to on-chip clock generation and control offers considerable system, power and area benefits over conventional PLL-based designs.

BENEFITS:

LOW POWER benefits
- estimated 80% net current saving compared to equivalent multi-PLL solutions

SYSTEM benefits
- SOFTWARE CONTROL OF ALL CLOCKS
  - enables aggressive power management scheme.
    - power gating
    - static and dynamic power savings
  - ELIMINATES PLL START-UP LATENCY
    - almost zero start-up delay
  - OTHER BENEFITS
    - all clocks are phase coherent through frequency hops, improving performance in many RF applications
    - simplifies frequency-hopping radio design

COST SAVINGS
- SHORTER DESIGN CYCLE : improves time to revenue
  - simple central clocking design
  - avoids multiple, separate-vendor PLL macros
  - validation: shorter simulation runs
  - faster hardware debug
- REDUCED BOM
  - can eliminate multiple crystals: lower system BOM cost
  - reduced test time: lower device cost
  - potential area reduction, depending on design

LOW POWER OPERATION

MCG offers considerable savings in power and cost compared to the multiple independent PLLs on a large SoC (see right), by using a highly efficient common clock-generation engine.

MCG consists of a central digital frequency generator (shown in yellow) with up to 256 programmable clock driver channels, each feeding an analogue processing stage (shown in blue) which controls the clock jitter and skew. Jitter is suppressed using Toric's PhaseFilter topology.

Each of these analogue stages can be placed at an optimal location on the IC; either next to the digital block, or adjacent to the circuit being clocked. An advantage of the latter option is that additional jitter accumlated in the clock routing path can be suppressed.

The MCG's frequency synthesiser can be driven by a single master clock source, whose frequency must be higher than the greatest clock frequency required. A basic low-power PLL can be used, since is jitter requirement is not critical.

PROGRAMMABLE FEATURES

Digital synthesis in combination with Toric's new technology allows precise control of clock generation. Dynamic control and gating of clock frequency is possible without the latency overhead associated with PLLs. MCG's control features include:

independent frequency selection for each channel
independent programmable skew correction for each channel
timing integrity of clock waveform over a frequency change
for frequency-hopping operation, phase coherency of each fixed frequency
modulation parameters for spread-spectrum
automatic power-down of idle clock channels

MCG FACILITATES CHIP POWER MANAGEMENT
Dynamic Voltage-Frequency Scaling (DVFS) and power-gating are widely used for power-sensitive IC applications, especially embedded processors and battery-powered devices. Until now, however, these techniques could not be used in clock generators and PLLs. Generally, they are kept powered-up and running because of the long stablisation time required immediately following a power-up or frequency change.

A major advantage of MCG is that the clock is available in a few cycles after power-up, and maintains timing integrity over a frequency change. There is none of the ‘out-of-lock’ behaviour associated with PLLs. This gives the programmer the opportunity to use power-gating and clock throttling more aggressively, without the restrictions typically imposed by PLL hardware, leading to improved net energy efficiency.

For more information : MCG Product Brief

DELIVERY

MCG will be available in 2008 as a design kit as follows:

VHDL and RTL source (for digital sections)
Analogue schematic
GDSII source (analogue sections) for TSMC 90nm and Cadence GPDK 90nm.
High-level hardware configuration utility
Test and verification vectors
Implementation manual
‘C’ library for low-level control functions
Cadence Virtuoso™ platform compatibility

Intermediate releases of MCG will be available for evaluation and for licensing into customers' own designs.