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Working much the same as the modular connectorized versions, the PLL ASIC has also been integrated within smaller SMT frequency-synthesizer products, in a compact 1.0 × 1.25 in. footprint. The single-loop surface-mount version is designed for use with input frequencies to 2.2 GHz and supplying stable, low-noise octave-band output signals to about 10 GHz. This surface-mount footprint (Fig. 3) has been used to accommodate a custom VCO for radar and communications-band frequencies. For this particular custom design, moderately wide locked bandwidths are achieved by using one of Synergy’s low-noise, wide-tuning-range microstrip VCO designs. For sources requiring reference frequencies below 100 MHz, internal low-noise reference multiplying techniques are employed to achieve the highest possible phase detector operating rate for best output noise performance that takes advantage of the PLL ASIC’s unique capabilities.

Fig. 3As an example of the source performance possible from synthesizers employing this novel ASIC in a single-loop configuration, model LSLO220270-500 is a phase-locked frequency synthesizer that delivers a 500-MHz output bandwidth from 2200 to 2700 MHz. It is designed to work with an 80-MHz frequency reference at +5 dBm and fits within the smaller 1.0 × 1.25-in. SMT housing. This RoHS-compliant frequency synthesizer tunes in 5-MHz steps and provides at least +8-dBm output power across its 500-MHz tuning range.

It achieves -23 dBc typical second-harmonic suppression with impressive SSB phase-noise performance (Fig. 4). Spurious noise levels are typically -65 dBc or better. The phase noise is a low -118 dBc/Hz even as close as 1 kHz from the carrier, dropping to -123 dBc/Hz offset 10 kHz from the carrier, better than -135 dBc/Hz offset 1 MHz from the carrier, and -155 dBc/Hz or less for offset frequencies beyond 1 MHz from the carrier. The signal source can be programmed by means of serial peripheral interface (SPI) or parallel port and features settling time within 100 μs to a new frequency when programmed with SPI fast-lock mode.

The 2.2-to-2.7-GHz source draws no more than 100 mA current from a +5-VDC supply and tunes by means of a +12-VDC source, drawing no more than 60 mA current. A +3,3-VDC digital supply draws maximum current of 550 mA. The 2.2-to2.7-GHz source is designed for an operating temperature range of -30 to +70°C. 

Fig. 4The surface-mount SLSO and SLFO sources also communicate using the simple channel-select SPI command interface. The surface-mount version can accommodate a limited channel number parallel interface using as many as seven parallel interface lines.

As with the company’s other single-loop and dual-loop phase-locked SMT source designs and VCO products, the 2.2-to-2.7-GHz frequency synthesizer employs the firm’s patented REL-PRO technology for reliable surface-mount electrical connections. The approach avoids the use of contacts with castellations, which are larger-diameter plated-through holes (PTHs) formed through printed-circuit boards (PCBs) to make electrical contacts and signal transitions between two or more PCBs in an assembly.

Since REL-PRO contacts do not critically depend upon the punching, routing, and alignment measures employed in forming castellation contacts, higher yields with more reliable contacts are possible with REL-PRO contacts than with standard PTH multiple-PCB connections. Unlike PCBs formed through a castellation process, the REL-PRO process does not produce the exposed copper from punching or routing PTHs. Without exposed copper, there is less concern about the long-term reliability problems resulting from oxidation and corrosion of that exposed copper.

The product lines of frequency synthesizers and phase-locked oscillators using this new ASIC are suitable for a wide range of applications through 15 GHz, including in microwave radios, satellite-communications (satcom) systems, radar systems, and test equipment. The sources are available for a standard operating-temperature range of -10 to +60°C and with an extended operating temperature range of -40 to +85°C also available. For single-loop and dual-loop frequency synthesizers, the standard connectorized module size is 2.5 × 2.5 × 0.5 in.

The frequency synthesizers provide standard output-power levels to +12 dBm, with optional output power to +16 dBm also available. The synthesized signal sources can be designed with dual RF/microwave frequency outputs or with a reference sample output in addition to the standard frequency output.

Synergy Microwave Corp., 201 McLean Blvd., Paterson, NJ 07504; (973) 881-8800, FAX: (973) 881-8361

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