Hittite Releases PLL with Integrated VCO Targeted at MIMO Architectures

Hittite Microwave Corporation, the world class supplier of complete MMIC based solutions for communication & military markets has launched the HMC835LP6GE, a Wideband Fractional-N PLL with Integrated VCO that generates continuous fractional frequencies between 33 MHz and 4100 MHz. Targeted at cellular infrastructure market, HMC835LP6GE features industry leading PLL & VCO phase noise performance with a PLL Figure of Merit of -230 dBc/Hz in integer mode, and -227 dBc/Hz in fractional mode, and typical VCO phase noise of -134 dBc/Hz at 4 GHz output frequency and 1 MHz offset.

Along with industry leading phase noise performance, the HMC835LP6GE includes advanced features demanded by modern LTE MIMO radio architectures. Two differential or 4 single-ended outputs enable a single HMC835LP6GE to drive multiple MIMO channels. The external VCO input allows the HMC835LP6GE to lock both integrated and external VCOs, and enables cascaded LO architectures for MIMO radio applications. Two separate Charge Pump (CP) outputs enable optimized loop filters, and seamless switching between integrated or external VCOs during operation.

Programmable RF output phase enables the use of multiple phase coherent LOs in scalable MIMO & beam-forming architectures. Separate, phase coherent LOs increase system phase noise performance (2 LOs by 3 dB, 4 LOs by 6 dB), and minimize crosstalk between MIMO channels. Reducing crosstalk increases the accuracy of MIMO channel estimation and thereby increases overall system throughput.

Integrated phase coherent frequency changes improve system performance of digital pre-distortion loops in cellular infrastructure applications by maintaining pre-distortion loop phase information, thereby enabling the pre-distortion loop to maintain convergence during frequency changes.

Additional features include configurable output mute function that mutes RF outputs during frequency changes, and Exact Frequency Mode that enables the HMC835LP6GE to generate fractional frequencies with 0 Hz frequency error.Samples and evaluation PC boards for all SMT packaged products are available from stock and can be ordered via the company's e-commerce site at www.hittite.com.