Plastic Surface-mount Doublers That Cover Up to 6 GHz
Hittite Microwave Corp.
Wireless communications applications continue to evolve at a furious pace. New applications are emerging endlessly such as wireless local loops and multipoint multichannel distribution systems. Wireless local area networks are increasing in frequency from 900 MHz to 2.4 GHz, with 5.2 GHz not far off. The digital microwave radio and very small aperture terminal products continue to thrive at traditional frequencies and are also moving up the frequency spectrum. All of these applications are faced with the challenge of high performance in small packages with low power consumption and low cost requirements.
Frequency multiplication is often a cost-effective approach to creating an LO or for signal translation in these higher frequency applications. Doublers are the most common multiplication building block at high frequencies and have long been offered in large connectorized packages. However, until now, frequency doublers have not been offered with surface-mount capability in industry-standard IC packages.
The models HMC187MS8 and HMC188MS8 GaAs MMIC frequency doublers fulfill these requirements while covering output frequency ranges of 1.7 to 4 GHz and 2.5 to 6 GHz, respectively. The devices are high performance, low cost and supplied in the industry-standard plastic eight-lead surface-mount mini small outline package (MSOP). The typical isolation performance of each device is shown in Figure 1 for a +15 dBm drive level. The incident fundamental frequency f0 is attenuated by at least 30 dB relative to the desired output frequency 2f0 . The higher order signal isolations, 3f0 and 4f0 , at the output of the HMC187MS8 relative to 2f0 are -37 and -25 dBc, respectively. The HMC188MS8 3f0 and 4f0 isolations are -35 and -30 dBc, respectively. These isolation specifications are the highest available in a surface-mount package. High isolation decreases the output filtering requirements for multiplier chains, saving board space and decreasing overall cost.
Fig. 1: Isolation for the (a) HMC187MS8 and (b) HMC188MS8 doublers.
The MSOP package saves more than 50 percent of the board area used by small outline IC (SOIC) or SOIC-like hybrid doubler packages, easily meeting the stringent Personal Computer Memory Cards International Association size constraints. The MSOP package occupies an area of 0.192" × 0.118", with a maximum height of 0.042". With a lead pitch of 25 mil, standard surface-mount manufacturing processes and equipment can be used. Lead coplanarity is maintained to 3 mils.
GaAs MMIC technology enables the doublers' small size and has the additional benefit of tight unit-to-unit consistency. The passive Schottky diode doublers require no DC bias and utilize on-chip baluns matched closely with the diode bridge, leveraged from mixer products covering the same frequency range. The doubling scheme contributes no measurable additive phase noise to the multiplied signal. This feature is important particularly for LO doubler applications. Monolithic construction ensures reliability and repeatability for the life of the product. The schematic for both devices is shown in Figure 2 .
Fig. 2: The doubler's schematic.
Conversion loss for the doublers is typically 15 dB at a drive level of +15 dBm. The conversion loss remains Figure 3 shows the conversion loss for the HMC187MS8 and HMC188MS8 doublers. The conversion loss varies only ±2 dB over the operating temperature and frequency ranges.
Fig. 3: Conversion loss for the (a) HMC187MS8 and (b) HMC188MS8 doublers.
The MMIC doublers are rated for an operating temperature range of -40° to +85°C and a storage range of -65° to +150°C. The maximum input drive level is +27 dBm. Currently, the HMC187MS8 and HMC188MS8 doublers are available for sample and production orders. Tape and reel is available, if required. Ceramic eight-pin packaged devices (C8 package style) in the doubler product family are also available, covering output frequencies to 8 Ghz.
Hittite Microwave Corp.,
Woburn, MA (617) 933-7267.