GHz V Low Current GaAs MMIC LNA Technical Data MGA-876 Features Ultra-Miniature Package.6 db Min. Noise Figure at. GHz. db Gain at. GHz Single + V or V Supply,. ma Current Applications LNA or Gain Stage for PCS, ISM, Cellular, and GPS Applications Equivalent Circuit INPUT Surface Mount SOT-6 (SC-7) Package Pin Connections and Package Marking GND GND INPUT 87 GND V dd Note: Package marking provides orientation and identification. 6 V dd 6 Description Hewlett-Packard s MGA-876 is an economical, easy-to-use GaAs MMIC amplifier that offers low noise and excellent gain for applications from to GHz. Packaged in an ultra-miniature SOT-6 package, it requires half the board space of a SOT- package. With the addition of a simple shunt-series inductor at the input, the device is easily matched to achieve a noise of.6 db at. GHz. For. GHz applications and above, the output is well matched to Ohms. Below GHz, gain can be increased by using conjugate matching. The circuit uses state-of-the-art PHEMT technology with selfbiasing current sources, a sourcefollower interstage, resistive feedback, and on-chip impedance matching networks. A patented, on-chip active bias circuit allows operation from a single + V or + V power supply. Current consumption is only. ma, making this part ideal for battery powered designs. GROUND,, 96-9688E 6-
Absolute Maximum Ratings Absolute Symbol Parameter Units Maximum [] V dd Device Voltage, V 6 Output to Ground V in input or Output V + V out Voltage to Ground. P in CW Input Power dbm + T ch Channel Temperature C T STG Storage Temperature C -6 to Thermal Resistance [] : θ ch-c = 6 C/W Notes:. Operation of this device above any one of these limits may cause permanent damage.. T C = C (T C is defined to be the temperature at the package pins where contact is made to the circuit board). MGA-876 Electrical Specifications [], T C = C, Z O = Ω, V dd = V Symbol Parameters and Test Conditions Units Min. Typ. Max. G test [] f =. GHz NF test [] f =. GHz.8. NF o Optimum Noise Figure f =.9 GHz db.9 (Tuned for lowest noise figure) f =. GHz.6 f =. GHz.6 f =. GHz.6 f = GHz. G a Associated Gain at NF O f =.9 GHz db.6 (Tuned for lowest noise figure) f =. GHz. f =. GHz f =. GHz. f = GHz. P db Output Power at db Gain Compression f =.9 GHz dbm -. f =. GHz -.8 f =. GHz -. f =. GHz -. f = GHz -.6 IP Third Order Intercept Point f =. GHz dbm +8 VSWR Output VSWR f =. GHz.8 I dd Device Current ma. Note:. Guaranteed specifications are % tested in the circuit in Figure in the Applications Information section. 6-
MGA-876 Typical Performance, T C = C, V dd = V NOISE FIGURE (db) +8 - + ASSOCIATED GAIN (db) - + +8 P db (dbm) - - - - - + +8............ -...... Figure. Minimum Noise Figure (Optimum Tuning) vs. Frequency and Temperature. Figure. Associated Gain (Optimum Tuning) vs. Frequency and Temperature. Figure. Output Power for db Gain Compression (into Ω) vs. Frequency and Temperature. NOISE FIGURE (db). V. V.7 V ASSOCIATED GAIN (db). V. V.7 V P db (dbm) - - - -. V. V.7 V............ -...... Figure. Minimum Noise Figure (Optimum Tuning) vs. Frequency and Voltage. Figure. Associated Gain (Optimum Tuning) vs. Frequency and Voltage. Figure 6. Output Power for db Gain Compression (into Ω) vs. Frequency and Voltage.. 6 VSWR (n:)..... INPUT NOISE FIGURE (db)...... NF Ga NF OPT ASSOCIATED GAIN (db) CURRENT (ma) +8 + + -.............. VOLTAGE (V) Figure 7. Input and Output VSWR (into Ω) vs. Frequency. Figure 8. Ω Noise Figure and Associated Gain vs. Frequency. Figure 9. Device Current vs. Voltage. 6-6
MGA-876 Typical Scattering Parameters [], T C = C, Z O = Ω, V dd = V Freq. S S S S K GHz Mag Ang db Mag Ang db Mag Ang Mag Ang Factor..9 - -.6-9 -.7.7-7.86 -...9-8 -.7.9 - -.7.7-9.8-8.9.88-6.7. - -..68-8.78 -...79 -.. -7 -.. -6.6-7.7..7-9..6 6-6..9 - -...67-6..7-6.6.7-9. -.. 9-69.. 9-9.. -. -.8. -78.7. -.. -. -67.9.. -8.. 8 -..8 -. 7 6.7.7-96..6 7-7.7. -. 9.8.. -9 8.7.7-6...... - 8.. -.9. -.7 7.8 MGA-876 Typical Noise Parameters [], T C = C, Z O = Ω, V dd = V Γ opt Frequency NF o (GHz) (db) Mag. Ang. R N / Ω.6.7.7..7.68 7.96..6.68 8.7..6.66 6.67..6.6 6..6 9 9..8 6. 6 8 Notes:. Reference plane per Figure in Applications Information section. 6-7
MGA-876 Applications Information Introduction The MGA-876 low noise amplifier is designed to simplify wireless applications in the to GHz frequency range. The MGA-876 is a two-stage, GaAs Microwave Monolithic Integrated Circuit (MMIC) amplifier that uses feedback to provide wideband gain. The output is matched to Ω and the input is partially matched for optimum noise figure. A patented, active bias circuit makes use of current sources to re-use the drain current in both stages of gain, thus minimizing the required supply current and decreasing sensitivity to variations in power supply voltage. Test Circuit The circuit shown in Figure is used for % testing of Noise Figure and Gain. The input of this circuit is fixed tuned for a conjugate power match (maximum power transfer, or, minimum Input VSWR) at GHz. Tests in this circuit are used to guarantee the NF test and G test parameters shown in the Electrical Specifications table. The.7 nh inductor, L (Coilcraft, Cary, IL part number series 8CT-) placed in series with INPUT Ω C L.7 nh V dd Ω Ω the input of the amplifier is all that is necessary to match the input to Ω at GHz. Phase Reference Planes The positions of the reference planes used to measure S-Parameters and to specify Γ opt for the Noise Parameters are shown in Figure. As seen in the illustration, the reference planes are located at the extremities of the package leads. Biasing The MGA-876 is a voltagebiased device and operates from a single + volt power supply. With a typical current drain of only. ma, the MGA-876 is very well suited for use in battery powered applications. All bias regulation circuitry is integrated into the MMIC, eliminating the need for external DC components. performance is very consistent for -volt battery supplies that may range from.7 to. volts, depending on battery freshness or state of charge for rechargeable batteries. Operation up to + volts is discussed at the end of the Applications section. The test circuit in Figure illustrates a suitable method for bringing bias into the MGA-876. The bias connection must be designed so that it adequately bypasses the V dd terminal while not inadvertently creating any resonances at frequencies where the MGA-876 has gain. REFERENCE PLANES TEST CIRCUIT The Ω resistor, R, serves to de-q any potential resonances in the bias line that could lead to low gain, unwanted gain variations or device instability. The power supply end of R is bypassed to ground with capacitor C. The suggested value for C is pf. Significantly higher values for C are not recommended. Many higher value chip capacitors (e.g., pf) are not of sufficiently high quality at these frequencies to function well as a bypass without adding harmful parasitics or selfresonances. While the input and output terminals are internally resistively grounded, these pins should not be considered to be current sinks. Connection of the MGA-876 amplifier to circuits that are at ground potential may be made without the additional cost and PCB space needed for DC blocking capacitors. If the amplifier is to be cascaded with active circuits having non-zero voltages present, the use of series blocking capacitors is recommended. Input Matching The input of the MGA-876 is partially matched internally to Ω. The use of a simple input conjugate matching circuit (such as shown in Figure for GHz), will lower the noise figure considerably. A significant advantage of the MGA-876 s design is that the impedance match for NF o (minimum noise figure) is very close to a conjugate power match. This means that a very low noise figure can be realized simultaneously with a low input VSWR. The typical difference Figure. Test Circuit for GHz. Figure. Reference Planes. 6-8
between the noise figure obtainable with a conjugate power match at the input and NF o is only about. db. Output Matching The output of the MGA-876 is matched internally to Ω above.8 GHz. The use of a conjugate matching circuit, such as a simple series inductor, can increase the gain considerably at lower frequencies. Matching the output will not affect the noise figure. Stability If the MGA-876 is cascaded with highly reactive stages (such as filters) some precautions may be needed to ensure stability. The low frequency stability (under. GHz) of the MGA-876 can be enhanced by adding a series R-L network in shunt with the output, as shown in Figure. The inductor can be either a chip component or a high impedance transmission line as shown in the figure. Component values are selected such that the output of the MGA-876 will be resistively loaded at low frequencies while allowing high frequency signals to pass the stability load with minimal loss. Typical values for the resistor are in the to Ω range. A suggested starting place for the inductor is a. to.-inch long microstripline with a width of. inches, using.-inch thick FR- (ε r =.8) circuit board as the substrate. For applications near. GHz, gain (and output power) may be traded off for increased stability. Some precautions regarding the V dd connection of the MGA-876 are also recommended to ensure stability within the operating frequency range of the device. It is important that the connection to the power supply be properly bypassed to realize full amplifier performance. Refer to the Biasing section above for more information. SOT-6 PCB Layout A PCB pad layout for the miniature SOT-6 (SC-7) package is shown in Figure (dimensions are in inches). This layout provides ample allowance for package placement by automated assembly equipment without adding parasitics that could impair the high frequency performance of the MGA-876. The layout is shown with a nominal SOT-6 package footprint superimposed on the PCB pads. Layout The layout in Figure is suggested as a starting point for designs using the MGA-876 amplifier. Adequate grounding is needed to obtain maximum performance and to obviate potential instability. All three ground pins of the MMIC should be connected to ground by using plated through holes (vias) near the package terminals. It is recommended that the PCB traces for the ground pins NOT be connected together underneath the body of the package. PCB pads hidden under the package cannot be adequately inspected for SMT solder quality. FR- or G- PCB material is a good choice for most low cost wireless applications. Typical board thickness is. or. inches. The width of Ω microstriplines in these PCB thicknesses is also convenient for mounting chip components such as the series inductor at the input.6 MGA 876 DC BLOCKING CAPACITOR - Ω.7 Ω V DD HIGH IMPEDANCE TRANSMISSION OR INDUCTOR..6 87 Ω INPUT Figure. Output Circuitry for Low Frequency Stability. Figure. PCB Pad Layout (dimensions in inches). Figure. Layout. 6-9
for impedance matching or for DC blocking capacitors. For noise figure sensitive applications, the use of PTFE/glass dielectric materials may be warranted to minimize transmission line losses at the amplifier input. 7 Higher Bias Voltages While the MGA-876 is designed for use in + volt battery powered applications, the internal bias regulation circuitry allows it to be easily operated with any power supply voltage from +.7 to volts. Figure shows an. increase of approximately db in the associated gain with + volts applied. The P db output power (Figure 7) is also higher by about dbm. The effect of higher V dd on noise figure is negligible as indicated in Figure 6.. ASSOCIATED GAIN (db) 6 OPTIMUM NF (db)..... P db (dbm) - -. -. 9...... Figure. Associated Gain vs. Frequency at V dd = Volts....... Figure 6. Optimum Noise Figure vs. Frequency at V dd = Volts. -..6..8...6. Figure 7. Output Power at db Gain Compression vs. Frequency at V dd = Volts. MGA-876 Part Number Ordering Information Part Number Devices per Container Container MGA-876-TR, 7" reel MGA-876-BLK Antistatic bag Package Dimensions Outline 6 (SOT-6/SC-7). (.) REF.. (.87). (.79). (.). (.). (.87).8 (.7).6 BSC (.). (.7) TYP.. (.). (.). REF.. (.). (.6). (.9).8 (.). (.). (.). (.8). (.) DIMENSIONS ARE IN MILLIMETERS (INCHES) 6-
Device Orientation REEL TOP VIEW mm END VIEW CARRIER TAPE 8 mm 87 87 87 87 USER FEED DIRECTION COVER TAPE Tape Dimensions and Product Orientation For Outline 6 P D P P E C F W t (CARRIER TAPE THICKNESS) D T t (COVER TAPE THICKNESS) 8 MAX. K MAX. A B CAVITY PEORATION CARRIER TAPE COVER TAPE DISTANCE DESCRIPTION SYMBOL SIZE (mm) SIZE (INCHES) LENGTH WIDTH DEPTH PITCH BOTTOM HOLE DIAMETER DIAMETER PITCH POSITION WIDTH THICKNESS WIDTH TAPE THICKNESS CAVITY TO PEORATION (WIDTH DIRECTION) CAVITY TO PEORATION (LENGTH DIRECTION) A B K P D D P E P. ±.. ±.. ±. ±.. +.. ±. ±..7 ±. W 8. ±. t. ±. C. ±. T t.6 ±. F. ±.. ±. 6-.88 ±..9 ±..8 ±..7 ±..9 +..6 ±..7 ±..69 ±.. ±.. ±.. ±.. ±..8 ±..79 ±. F y o A F J E l a D C O P