MA46450 through MA46480 Series 1.00 and 1.25 Gamma GaAs Hyperabrupt Tuning Varactors 30 277 7} Description The MA46450 series and the MA46470 series of tuning varactors are hyperabrupt junction Gallium Arsenide devices featuring constant gamma of 1.0 (MA46450 series) and 1.25 (MA46470 series). These series offer high Q (up to 4000) that permit excellent tuning performance from VHF through Ka-band. Each device in these series exhibits the large capacitance change with voltage of hyperabrupt tuning varactors. Standard capacitance matching is +10%, with closer matching available on request. All diode types are available in a wide selection of ceramic packages and in chip form. Features @ CONSTANT GAMMA = 1.0 OR 1.25 @ HIGH Q (UP TO 4000 AT - 4 VOLTS) lM LARGE CAPACITANCE CHANGE WITH VOLTAGE @ MORE LINEAR FREQUENCY TUNING @ HIGH AND NEARLY CONSTANT MODULATION SENSITIVITY Applications The constant gamma value of 1.0 or 1.25 available from these diodes permits significant circuit performance improvements for the circuit designer. Constant gamma tuning varactors permits more linear VCO frequency tuning with bias voltage than conventional varactors. These varactors are also useful for tunable filters and can improve the frequency tuning linearity of these circuits. These diodes are an excellent choice for modulator applications where excellent linearity and constant modulation sensitivity is desired. M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 * (617) 272-3000 TWX 710-332-6789 * TELEX 94-94645-26 MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors Specifications @ Ta = 25C MA46450 Series GaAs Constant Gamma Hyperabrupt Tuning Varactors Gamma = 1.0 Breakdown Voltage = 22 Volts Minimum Gamma Constant = 1.0 + 10% 2-20 volts MA46470 Series GaAs Constant Gamma Hyperabrupt Tuning Varactors Gamma = 1.25 Breakdown Voltage = 22 Volts Minimum Gamma Constant = 1.25 + 10% 2-20 Volts Minimum Capacitance Tolerance? + 10% Capacitance Tolerance? = + 10% Total, 2; 5 Total*, 2, 5 Capacitance |Capacitance?: 9] Q at Capacitance |Capacitance?: | Q at Modelt Case @ 4 Volts Ratio (2/20) | -4 Volts Model! Case @ -4 Volts Ratio (2/20) | 4 Volts Number Style (+ 10%) (pF) Min./Max. Minimum Number Style | (110%) (pF) Min./Max. 50 MHz MA46450 30 05 2.0/2.7 4000 MA46470 30 05 2.2/3.2 4000 MA46451 30 0.7 2.9/4.1 4000 MA46471 30 0.7 3.6/5.3 4000 MA46452 30 1.0 3.6/5.2 3000 MA46472 30 1.0 4.8/7.1 3000 MA46453 30 1.2 3.6/5.2 3000 MA46473 30 1.2 4.8/7.1 3000 MA46454 30 15 3.8/5.5 3000 MA46474 30 15 5.0/7.4 3000 MA46455 30 18 4.1/6.1 3000 MA46475 30 18 6.6/8.7 3000 MA46456 30 2.0 4.1/6.1 3000 MA46476 30 2.0 6.6/8.7 3000 MA46457 30 2.2 4.1/6.1 3000 MA46477 30 2.2 6.6/8.7 3000 MA46458 30 2.7 4.5/6.7 2000 MA46478 30 27 6.40.0 2000 MA46459 30 33 4.5/6.7 2000 MA46479 30 3.3 6.4/0.0: 2000 MA46460 30 3.7 477A 2000 MA46480 30 3.7 6.8/11.0 2000 MA46461 30 4.7 4.8/7.2 1500 MA46481 30 47 6.9/11.1 1500 MA46462 30 56 4.9/7.4 1500 MA46482 30 56 7.2N15 1500 MA46463 30 68 4.9/7.4 1500 MA46483 30 68 7.215 1500 MA46464 30 8.2 5.0/7.6 1500 MA46484 30 8.2 7.215 1500 MA46465 30 10.0 5.0/7.6 1500 MA46485 30 10.0 75N2.0 1500 NOTES: 1. All GaAs tuning varactors are available upon special request in chip form as well as any other case style and the standard ODS - 30 package. When ordering, specify the desired case by adding the case designation as a suffix to the type number. 2. Case parasitics (C, and L,) are given for most case styles along with case outlines in this bulletin. The Cy values listed typically have tolerances of +0.02 pF. 3. The nominal tolerance at 4 volts is + 10%. Closer tolerances are available upon request. By adding the suffix A to the part number, a tolerance of + 5% can be obtained. 4. Gamma is within the timits of 090 < < 1.10 over the voltage range of 2-20 volts for the MA46450 series. Gamma is within the limits of 1.13 < y < 140, over the range of 2-20 volts for the MA46470 series. Total capacitance of the packaged diodes will deviate from constant gamma characteristics due to differences in case capacitance (C,). Figures 1 and 4 illustrate typical total capacitance versus applied voltage for these series when case style 30 is selected. Figure 3 illustrates the typical range of y versus voitage when case style 30 is selected. Figures 2 and 5 illustrate typical capacitance ratios versus applied voltage in case style 30. Capacitance is measured at 1 MHz using a shielded test holder. Diode Q is measured by the DeLoach technique at -4 valts and ex- trapolated to 50 MHz. Parasitic inductance (L,) has been determined at X band using the DeLoach method measurement. Breakdown voltage (Vp) is measured at 10 microamps. The total capacitance and capacitance ratios shown are for devices housed in case style 30. Other case styles will result in different values. Dn N Oo @ Electrical Characteristics (at 25C) MAXIMUM RATINGS Operating Temperature Storage Temperature Reverse Voltage 65C to + 200C - 65C to + 200C Breakdown Voltage ENVIRONMENTAL RATINGS PER MIL-STD-750 TUNING VARACTOR EQUIVALENT CIRCUIT R, c,(v) L, QQ -_o MIL Method _ Level Storage Temperature 1031 See maximum ratings Operating Temperature See maximum ratings Temperature Cycle 1051 10 cycles, -65C to +175C Shock 2016 500 gs Vibration 2056 15 gs Constant Acceleration 2006 20,000 g's Humidity 1021 10 days M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 (617) 272-3000 * TWX 710-332-6789 * TELEX 94-9464Typi TOTAL CAPACITANCE, cy (pF) cal Performance Curves 10 8 AGg> MA46473 MA46, 77 0.6 0.4 0.2 0.1 1 2 3 4 5678910 20 REVERSE BIAS VOLTAGE (VOLTS) 30 FIGURE 1. Total Capacitance vs. Reverse Bias Voltage TOTAL CAPACITANCE, cy (pF) (Case Style 30) MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors CAPACITANCE RATIO Cl /Cly - UA OOS MA46471 1 2 3 4 5 678 1012 REVERSE BIAS VOLTAGE (VOLTS) 20 FIGURE 2. Capacitance Ratio vs. Reverse Bias Voltage (Case Style 30) 2.0 1.75 | 1.50 = +10% MA46470 SERIES 4 I 1.25 Lif if ff tft og hhh behead anh hk id Lif fff if 4 +10% MA46450 SERIES i Lift ft hh hhh hh hhh hh Lk tft fF LY 0.5 0 2 4 6 8 10 12 14 16 18 20 VOLTAGE (VOLTS) FIGURE 3. Gamma vs. Voltage _ aA owed N gs oo = 2 b 9 Nd 2 a 20 1 2 3 45 67810 30 REVERSE BIAS VOLTAGE (VOLTS) FIGURE 4. Total Capacitance vs. Reverse Bias Voltage M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 (617) 272-3000 * TWX 710-332-6789 * TELEX 94-9464 (Case Style 30) CAPACITANCE RATIO C, ,/C, ,, = >- On Owd E=0.18 CHIP MA46454 1 2 3 REVERSE BIAS VOLTAGE (VOLTS) 4 5 678 1012 20 FIGURE 5. Capacitance Ratio vs. Reverse Bias Voltage (Case Style 30) 5-275-28 MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors Application Notes SELECTION OF CONSTANT GAMMA HYPERABRUPT TUNING VARACTORS For varactors, the dependence of junction capacitance, Cj, on applied voltage, V, is given by: o (1) cj = a+ YR) @ = the built in potential (7=13 volts for GaAs) Co = aconstant (mathematically extrapolated to junction capacitance at V = 0) y = the capacitance-voltage slope exponent (gamma) For simple abrupt junction varactors, gamma is constant and nominally equal to 0.5. The junction is referred to as hyperabrupt when gamma is >0.5 and for most varactors, the value of gamma varies widely with applied voltage. From Equation (1), we observe that gamma is graphically determined as the slope of junction capacitance, Cj, asa function of total voltage (applied voltage plus built-in poten- tial) plotted on log-log paper. A typical plot of the constant gamma hyperabrupt tuning varactor C-V characteristics is illustrated in Figure A, where the slope of the curve is a constant gamma = 1.25 over the applied voltage range of 2-20 volts. Notice that constant gamma is not maintained at low applied voltages, so Cg = 66 pF is a mathematical value determined by extending the constant slope to V=0 or (V + = 1.3). The capacitance versus applied voltage, Curve 2, is also shown in Figure A for the chip, and Curve 3 illustrates the C-V curve when the chip is mounted in a style 30 package having a package capacitance of ~0.18 pF. The primary purpose of the constant gamma hyperabrupt varactors is to permit the designer to approach linear fre- quency tuning without the use of a linearizer. For a simple resonant circuit comprised of an inductance, L, and a varac- tor with junction capacitance Cj (V), the frequency-voltage relationship is given by: 1 1 Vv /2 fr(V) = = 9 WR)? nv LCj (V)4 2n Vv LCo 8 and the desired gamma value for linear tuning is 2.0. In all microwave oscillator circuits, the varactor is not the only capacitor in the resonant circuit. Instead, this capaci- tance makes up only a portion of the total resonant capacitive element. An analysis has been performed of the simple series circuit illustrated in Figure B where a fixed capacitor, Cg, is in series with the varactor junction. The results of this analysis provides guidance to the selection of a suitable gamma. The total capacitance, Cy of the resonant circuit can be expressed in terms of a coupling factor, Ks, as: 1 1 Vv =: eT - -) Y Ct (V) Cto [1 Ks + Kg (1 +=) ] where: Ks = Cto = total capacitance of resonator at V = 0 Co = varactor junction capacitance at V = 0 when Kg = 1, the varactor is fully coupled and the value of gamma for linear tuning is 2.0. As Kg approaches 0, the varactor becomes decoupled and the optimum gamma for linear tuning approaches 1.0. An optimum value of gamma for linear frequency tuning is predictable and the result is illustrated in Figure C. In this il- lustration, the optimum gamma value is plotted versus the frequency fmax/fmin, the coupling factor, Ks, as a parameter. Notice that linear tuning can be achieved for coristant gam- ma within the limits 10 < y < 2.0 depending on the coupl- ing factor. A circuit designer can use this simplified analysis for selec- tion of constant gamma hyperabrupt varactors. For example, suppose a circuit requirement is for a tuning ratio of 2:1. The designer could select y = 2 and fully couple the varac- tor with Cmax/Cmin < 4. Alternatively, if the circuit is de- coupled to Kg = 0.6 where y = 16 and Cmax/Cmin > 6. The further decoupling can also be considered with cor- respondingly lower optimum y. The decoupling limit occurs when the Cmax/Cmin is not available in the varactor. It has been empirically found that to obtain the best ncise and bandwidth characteristics, most moderate bandwidth voltage controlled oscillators will have varactor coupling factors (Kg) of 0.2-0.4. Most moderate power C and X band bipolar or FET oscillator transistors will have a Cc, of approximately 0.25 pF. 50-100 mW Gunn diodes have similar capacitances. (For further discussion on varactor coupling refer to M/A-COM SPOs article Tuning Varactor Diode Selection Guide, 1986). These broadband tuning requirements are optimized in circuits with 1.2 < y < 1.4, while circuits with narrow tuning bandwidth need to utilize a value of gamma approaching 1.0. Linearity improvement with these varactors is frequently a factor of 10 or more in comparison to conven- tional abrupt junction varactors. A. capacitance vs [sp- plied voltage + built-in Poten- tial] (@ = 1.3 volts tor GaAs). x 2 ~ 3. Total capacitance vs applied 2 voltage for case style 30 uw (Cp = 0.18 pF). 2 a 1 Fos oO az 0.6 a. S 0.4 2, Junction capacitance vs ap- plied voltage (chip only). 0.2 0.1 1 2 3 4567810 20 $0 VOLTAGE (VOLTS) FIGURE A. Typical GaAs Hyperabrupt C-V Characteristics M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 (617) 272-3000 TWX 710-332-6789 * TELEX 94-9464MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors Application Notes (Cont'd) C MAX CAPACITANCE RATIO C MIN 2 4 6 9 2.0 0 1.9 O 18 ALA n porn) 17 eer haa 0.6 b> 16 x & L = a4 04 2 15 1 wat 2 s a. - AT = & 1.4 eee O20 v7 a - 1] eT r Cj (Vv) 1.3 y , ee T 1.2 Leer . oa A C, 1 1.5 2.0 2.5 3.0 = =~ o f, = {MAX FREQUENCY RATIO R (722) FIGURE B. Resonant Circuit With Decoupled Tuning FIGURE C. Optimum ; Selection for Linear Tuning Varactor Case Styles 30 nat A DIA. 0.119 0.060 0.205 0.085 0.060 0.060 0.016 0.079 baal FV > o A B Cc D E F G H O ln ha on Be .18 pF Typical Cp = 0. = 0.40 nH Typical : Lg DIA. M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 (617) 272-3000 * TWX 710-332-6789 * TELEX 94-9464 5-29MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors Case Styles (Contd) 31 A DIA. INCHES MILLIM MIN. oa | 0.119 0.127 3,02 3 e , 0.085 0.097 2,16 2,46 f ~ 0.016 0.024 0,41 0,61 B t 0.077 0.083 1,96 2,11 Y_ Cp = 0.18 pF Typical =F Lg = 0.40 nH Typical 91 E + pia. MIN. ~~ D p> DIA. 0.119 A 0.115 Cc 0.060 e t | 0.060 A 0.077 Gc ol 0.016 Y F t Cp = 0.15 pF Typical Lg = 0.17 nH Typical $A DIA. >| 94 D } pa. INCHES MILLIMETERS e DIM. MIN. | MAX. MIN. | MAX. 4 | A 0.078 0.086 1,98 2,18 BY B 0.040 0.050 1,02 1,27 Cc _ 0.015 _ 0,38 | A | D 0.047 0.053 4,19 1,35 DIA. Cp = 0.15 pF Typical Lg = 0.17 nH Typical M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 (617) 272-3000 * TWX 710-332-6789 * TELEX 94-9464 5-30MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors Case Styles (Contd) 97 | <_p-_] INCHES MILLIMETERS Ls be DIM. MIN. | MAX. MIN. | MAX. _| e | A 0.076 0.086 1,98 2,18 } TYE B 0.100 0.110 2,54 2,79 Dia ota. LC DIA. C 0.024 0.026 0,61 0,66 D _- 0.015 ~ 0,38 E 0.040 0.050 1,02 1,27 pl F 0.004 0.010 0,10 0,25 lola G 0.029 0.031 0,74 0,79 D H 0.047 0.053 1,19 1,35 a EP} Cp = 0.15 pF Typical Lg = 0.17 nH Typical 120 INCHES MILLIMETERS DIM. MIN. | MAX. MIN. | MAX. A 0.051 0.055 1,30 1,40 B 0.040 0.050 1,02 1,27 Cp = 0.13 pF Typical Lg = 0.40 nH Typical 186 INCHES MILLIMETERS DIM. MIN. | MAX. MIN. [| MAX. A 0.094 0.102 2,39 2,59 B 0.031 0.044 0,79 1,12 C 0.019 0.021 0,48 0,53 D 0.003 0.006 0,76 0,15 E 0.130 0.170 3,30 4,32 Cp = 0.15 pF Typical Lg = 0.40 nH Typical M/A-COM SEMICONDUCTOR PRODUCTS OPERATION Burlington, MA 01803 (617) 272-3000 TWX 710-332-6789 TELEX 94-9464 5-315-32 MA46450-MA46470 Series GaAs Hyperabrupt Tuning Varactors Case Styles (Contd) 276 I 4 INCH ILLIMET! A D DIM. MIN. MAX. MIN. MAX. - -t | A 0.010 0.020 0,254 0,508 t_ B 0.040 0.050 1,02 1,27 c C _ 0.005 _ | 0,127 he = Bes D 0.051 0.055 1,29 1,39 E 0.200 5,08 _ F F 0.019 0.021 0,483 0,533 | Cp = 0.13 pF Typical Lg = 0.40 nH Typical E Chip Style 277 |~a>| INCHES MILLIMETERS DIM. MIN. | MAX. MIN. | MAX. A 0.010 0.012 0,25 0,31 | B 0.004 0.005 0,10 0,13 __ _ ___3 M/A-COM SEMICONDUCTOR PRODUCTS OPERATION * Burlington, MA 01803 (617) 272-3000 * TWX 710-332-6789 * TELEX 94-9464