DC-8 GHz Ultra Low Noise Fractional PLL!

As Quadrature Amplitude Modulation (QAM) in microwave radios moves to higher constellations, and signal bandwidths are tightening, excellent phase noise and spurious product performance is mandatory. The HMC703LP4E provides the ideal solution for the tough Error Vector Magnitude (EVM) and integrated phase noise specifications that these high data rate, frequency-efficient telecommunications systems require.

The HMC703LP4E features Frequency Shift Keying (FSK) modulation as well as bi-phase modulation with data rates limited by the loop filter bandwidth (typically 100 kHz). It also features a built-in sweeper mode that supports external or automatic triggered sweeps. The phase coherent frequency sweep mode can be used in test instrumentation, Frequency Modulated Continuous Wave (FMCW) sensors and automotive radars. Depending on the chosen Phase Locked-Loop (PLL) bandwidth the one or two-way frequency ramp may be continuous, or in steps.

The HMC703LP4E offers superb phase noise performance of -112 dBc/Hz at an offset of 50 kHz and a VCO frequency of 8 GHz in fractional mode. Its Floor Figure of Merit is -230 dBc/Hz in fractional mode; a performance that is typically 10 dB better than the performance of its closest competitor. When tested with the HMC508LP5E VCO, the jitter corresponding to double side-band phase noise integration from 100 Hz to 100 MHz offsets is 70.7 fs. This jitter would correspond to an EVM of 0.35% at 8 GHz and a Signal-to-Noise Ratio (SNR) of 49 dB.

Fractional synthesizers that set the channel step size with the fractional modulus often suffer from channel spurs. The HMC703LP4E exact frequency mode achieves exact channel frequencies with zero channel spurs, while double buffering enables strobed frequency hopping. The HMC703LP4E maximum PFD frequency is 115 MHz (in integer mode), which permits wider loop bandwidth, improved phase noise performance and faster locking/switching time. Typical in-band integer boundary spur is -60 dBc.

The HMC703LP4E maintains foot print compatibility for the main functions with its predecessor the HMC700LP4E. The HMC703LP4E is housed in a 4 x 4 mm plastic leadless surface mount package and provides excellent temperature stability over the -40 °C to +85 °C temperature range. Samples and evaluation PC boards are available from stock and can be ordered via the company's e-commerce site or via direct purchase order. Released data sheets may be found at www.hittite.com.