Silicon Creations LC-based PLL IP Products

In applications where ultra low jitter/phase noise is required, a high quality LC PLL is needed. Fully integrated LC Tank based PLLs can achieve 20-60 times lower phase noise for a given power specification than a ring based PLL. This makes LC Tank based PLLs optimal for high performance applications such as wireless, high speed IO, or clocking of high resolution data converters.

LC-based PLLs have historically been difficult to design due to poor modeling of integrated inductance, substrate losses, and package parasitics. In addition, classical LC PLLs have a very narrow frequency tuning range making it possible that the VCO will not be capable of oscillation at the desired frequency. However, Silicon Creations has overcome these problems in two ways:

  • First, a high quality coarse tuning element is used which gives a single VCO a wide tuning range to overcome PVT variations and model inaccuracy.
  • Additionally, a multiple VCO core design has been developed and can be used to cover up to a 2:1 frequency range.
Examples of the multiple VCO core design are shown in the right hand column.

Silicon Creations has LC PLL designs in technologies from 90nm to 180nm CMOS and with frequencies from 1.4GHz to 6.25GHz. Applications range from optical communications to RF synthesis. Send us an email to request a datasheet.

Shown above: Phase noise results for an S-Band fractional-N synthesizer with a 40MHz reference and multiply by 55+3/8.
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Silicon Creations LC-based PLLs

Shown above: A fractional-N synthesizer with a 4 VCO core targeted at high performance (1024 QAM) S-band applications over a 1.9-3.8GHz range.
Shown above: A delta-sigma fractional-N synthesizer with a 4 VCO core targeted at SONET and Ethernet applications up to 2.488GHz
Shown above: An optical link chipset containing an LC based 5.3GHz serializer and an LC based 5.3GHz CDR.
Shown above: A test chip containing multiple VCO cores targeted for use in SONET OC-192 and 12.5Gb/s Fiber Channel CDR applications