ALPHA IND/ SEMICONDUCTOR 4W8E D MM 0585443 0001307 4aT MMALP High Q GaAs Abrupt Tuning Diode Chips Features @ High Q - 4,000 to 15,000 mM Wide Tuning Capacitance Variation: 4/1 and 6/1 Typical @ Low Leakage - Nitride-Oxide Passivated @ X through Ka-Band Types m CVE7800 (25 Volt Series) mM CVE7900 (45 Volt Series) T-07-19 Description Alpha now offers passivated abrupt gallium arsenide tuning diodes in chip form. The passivation, in conjunc- tion with other processes, results in high reliability and leakage currents less than 10 nanoamps. Variations from square law are minimized while maintaining high tuning ratios and highest Q by a careful selection of epitaxial GaAs, and by anode diffusions that are tightly controlled. Applications These GaAs chips are ideally suited for frequency tuning applications from X through Ka-band. They may be used to tune filters, phase shifters, Gunn-Impatt- transistor oscillators, upconverters, and low order multi- pliers. Elimination of the package parasitics allows a lower breakdown voltage and a higher Q diode to be used for a given bandwidth specification. This will result in less insertion loss and lower noise operation. For very high frequency application, i.e, Ka-band and above, a chip is essential for all but the narrowest band specifications. For circuits in U, V, and W band, beam-lead varac- tors are offered. See page 4-32. Mechanical Details Allchip lots are characterized for Q-4 in our 023-001 package. They are also put on burn-in to check the reliability of the lot. During assembly the diodes are tested for die shear and strap pull strength. The die have bondable gold contacts on both sides. Special barrier underlying metals are used to prevent gallium migration and subsequent oxidation of the anode bond surface. Pull strengths meet MIL-STD-750. Mesa sizes vary from 1.6 to 4.5 mil diameter depending on the capacitance. Anode bond diameters vary from 1.4 to3.5 mils. Die size is .010" nominal. Epoxy or gold-germanium solder is the recommended die attach technique. For strap bonding a thermocompression bond should be made. The passivation is nitride-oxide depos- ited by the latest plasma techniques. This passivation extends over the top surface of the mesa (see Figure 1). Care must be taken to use a strap bond tool smaller than the passivation opening to avoid cracking the dielectric. Note that the gold surface will be brighter in the anode bond area. See Section 7 for suggested bond force and temperature. Ultrasonic bonding may be used on the larger di- ameter high capacitance diodes. Chips can also be of- fered with various straps attached. They also may be mounted on various metal or ceramic carriers for some microstrip applications. Consult factory for more infor- mation. 4-9 ALPHA IND/ SEMICONDUCTOR HOE D MM 0585443 o00130a J1lb MBALP 7-074 High Q GaAs Abrupt Tuning Diode Chips Model Number Model Number CVE7800 CVE7900 25 Volt Series'# 45 Volt Series? GaAs Abrupt High "Q" Chips CYC, =3.7/1 CJC. = 6/1 Suffix Number |C,(min.-max.)| C_,(typ.) Q_,(50MHz) Q_,(50MHz)* -06 4-6 .20 15,000 10,000 -12 .6-.8 35 13,000 9,000 -18 .8-1.0 45 12,000 8,000 -24 1.0-1.5 .60 10,000 7,000 -30 1.5-2.0 -90 7,500 6,000 -36 2.0-2.5 1.10 6,500 5,500 -42 2.5-3.0 1.40 5,500 5,000 -48 3.0-4.0 1.75 4,300 4,200 Notes: 1. Voltage breakdown is specified at 10 microamps. Higher voltage breakdown is available on request. 2. Reverse leakage current at 80% of rated breakdown voltage is 50nA max. 3. Tighter tolerances are available on request. 4, C/C,, is the typical capacitance ratio when the chip is blased from zero volts to the breakdown voltage. 5. The Q of the chip lot is characterized at -4 volts using a resonant cavity between 1 and 2 GHz. The Q is then extrapolated down to 50 MHz assuming a constant series resistance. 6. Add suffix number to Alpha Model Number to specify desired electrical characteristics; Example: CVE7800-18 Outline Drawing Figure 1 METALIZED soLopaoT J SILICON | A METACIZED BACK : CONTACT-GOLO 4 T +r GaAs - Bond Area (anode) Mesa Passivation Inches MM Chip Style | Dim A] DimL | Dim T | DimA]| DimL | DimT Min. | Nom. | Nom. | Min. | Nom. | Nom. 150-808 0012 .010 .005 .030 25 13 4-10