Programmable Low Phase Noise, less than 290fs jitter PLL with Integrated VCOs

Programmable clock multiplier (CMU) with three selectable frequency ranges of internal PLL
External RC loop filter
LVDS input reference clock interface
Fully differential CML output full-rate clock interface
Selectable LVDS output clock divided-by-16 interface
3-state input control interface
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Frequency (min): 24.0 GHz
Frequency (max): 32.1 GHz
Power: 450-530 mW
Package: 24-pin CQFP
Price: Request

Product Details

asnt8151-kmc desc

Fig. 1 Functional Block Diagram

ASNT8151-KMC is a clock multiplication unit (CMU) with a triple-range phase-locked loop (PLL) incorporating three high-speed voltage-controlled oscillators: VCO1 (lower frequency), VCO2 (medium frequency), and VCO3 (higher frequency). The chip shown in Fig. 1 generates a high-speed clock signal cp/cn with its phase and frequency locked to those of the incoming reference clock crp/crn. The differential clock cp/cn with frequency f is delivered to the output by CML output buffer HS COB. The reference clock crp/crn with frequency f/16 is accepted by LVDS input buffer LS CIB. The chip also generates a divided-by-16 clock signal c16p/c16n with frequency f/16 that is delivered to the output by LVDS output buffer LS COB.  One of the VCOs is activated using two 3-state control signals vc0 and vc1. The same control signals are used to activate or disable the output buffer LS COB. When operating in closed-loop mode, the PLL requires an external loop filter connected to pin fltr. The PLL also supports an open-loop mode of operation with its selected VCO controlled externally by a voltage applied to the filter pin fltr.


The part’s high-speed output buffer supports the CML logic interface with on chip 50Ω termination to vcc and may be used differentially, AC/DC coupled, single-ended, or in any combination. The part’s low-speed I/Os support the LVDS interface with internal 100Ω termination between the direct and inverted lines. The differential DC signaling mode is recommended for optimal performance.