Application Note Adapting the ACA0861C for 50 V Operation Rev 0 RELEVANT PRODUCTS • ACA0861C INTRODUCTION Introduction This Application Note describes the performance that is obtained when the ACA0861C 75 V Differential Amplifier IC is adapted for operation in a 50 V Singleended mode. Background The ACA0861C is traditionally used as a “50 MHz to 1000 MHz” linear power amplifier in 75 V CATV distribution trunks. Components in this type of service must, by default, possess superior broadband linearity performance and be ruggedized to withstand harsh environments. These attributes make the ACA0861C especially suitable for use as a 50 V Amplifier in systems that depend upon highly linear and reliable components. 50 V Matching Circuits Although the ACA0861 is optimized for broadband 75 V systems, it can be adapted to operate in 50 V systems by incorporating matching elements tailored for specific frequency segments. Any segment within the range of 50 MHz to 1100 MHz may be chosen. Three matching circuits and the associated performance data are presented below for specific segments centered at 150 MHz, 450 MHz, and 950 MHz. Other frequencies may be utilized by modifying the values of the passive matching elements. Internal Block Diagram The internal block diagram of the ACA0861C is illustrated below in Figure 1. The IC is fabricated entirely in Gallium Arsenide (GaAs) and consists of a cascaded pair of differential amplifiers with a pair of biasing drivers. 1 16 Bias 2 15 Driver AMP 1A 3 AMP 1B 14 4 13 5 12 AMP 2A 6 7 Bias AMP 2B 11 10 Driver 8 9 Figure 1: ACA0861 Internal Block Diagram 06/2010 ADAPTING THE ACA0861C FOR 50 V OPERATION +12V 0.01uF 330nH RF IN (75-ohms) MABA009210 0.01uF 300pF 15 3 MABA009210 14 RF OUT (75-ohms) ACA0861C 11 6 1:1 0.01uF 7 1:1 10 300pF 330nH 121 0.01uF +12V Figure 2: Single-Stage Amp (#2) Configuration The Test Circuit pictured above depicts the amplifier in a 75 V, differential mode of operation. A pair of 1:1 balun transformers matches the 37.5 V (differential) at the input and the output ports to the system impedance of 75 V (single-ended). The DC supply voltage of +12 Vdc is applied through the pair of 330 nH inductors. The biasing is set externally via a resistor placed between pin #7 and ground. The typical current consumption is approximately 260 mA. +Vdd RF IN (50-ohms) 3 15 14 ACA0861C 11 6 7 10 +Vdd Figure 3: Modified Configuration (simplified) 2 Application Note - Rev 0 06/2010 RF OUT (50-ohms) ADAPTING THE ACA0861C FOR 50 V OPERATION Only a few modifications to the standard 75-ohm (differential) Test Circuit are required to re-configure the ACA0861C for 50-ohm (single-ended) operation. The baluns are removed and the two differential ports are combined into a single-ended port at both the input and the output. High-pass and low-pass matching networks are utilized to optimize the returnloss at the desired frequency range of operation. An external bias voltage, applied to pin #7 via the pull-up resistor connected to pin #10, sets the desired Idd operating point. PERFORMANCE DATA - 150 MHz Table 1: 150 MHz 12 V PARAMETER MIN TYP MAX UNITS Frequency 100 150 200 MHz VDD - 12 - VDC IDD 400 500 600 mA Gain - 10.5 - dB Noise Figure - 3.0 - dB Output Power - +20 - dBm OIP31 - +57 - dBm P1dB - +31.5 - dBm NOTE: 1. Measured using two CW tones at an output power level of +20 dBm per tone. Table 2: 150 MHz 8 V PARAMETER MIN TYP MAX UNITS Frequency 100 150 200 MHz VDD - 8 - Vdc IDD 400 450 600 mA Gain - 10.5 - dB Noise Figure - 3.0 - dB Output Power - +16 - dBm OIP31 - +52 - dBm P1dB - +28.5 - dBm NOTE: 1. Measured using two CW tones at an output power level of +16 dBm per tone. Application Note - Rev 0 06/2010 3 ADAPTING THE ACA0861C FOR 50 V OPERATION +Vdd C6 0.01uF L1 20nH RF IN (50-ohms) C1B 2pF C1A 18pF R1 1.3ohm C2 100pF 15 3 U1 L5 23nH C4 82pF 14 RF OUT (50-ohms) ACA0861C 11 6 L2 39nH 7 10 L3 22nH L6 420nH R2 1.3ohm C7 0.01uF R5 20k C3 12pF C5B 2pF C5A 15pF L4 33nH R3 1.3ohm R4 1.3ohm +Vdd Figure 4: 150 MHz Circuit Figure 5: 150 MHz S21 Graph 11 10 9 8 S21 (dB) 7 6 5 4 3 2 1 0 25 50 75 100 125 150 175 200 225 Frequency (MHz) 4 Application Note - Rev 0 06/2010 250 275 300 325 350 375 400 ADAPTING THE ACA0861C FOR 50 V OPERATION Figure 6: 150 MHz S11, S12, S22 Graph 0 -5 S11, S12, S22 (dB) -10 -15 -20 S22 S12 -25 S11 -30 0 50 100 150 200 250 300 350 400 Frequency (MHz) Figure 7: Typical OIP3 (20 dBm POUT) vs IDD @ 12 V (150 MHz) Typical OIP3 (16 dBm POUT) vs IDD @ 8 V (150 MHz) 65.0 OIP3 (dBm) 60.0 Vdd = +12Vdc 55.0 Pout = +20dBm/tone 50.0 Vdd = +8Vdc 45.0 Pout = +16dBm/tone 40.0 400 450 500 550 600 Idd (mA) Application Note - Rev 0 06/2010 5 ADAPTING THE ACA0861C FOR 50 V OPERATION PERFORMANCE DATA - 450 MHz Table 3: 450 MHz 12 V PARAMETER MIN TYP MAX UNITS Frequency 350 450 500 MHz VDD - 12 - VDC IDD 400 475 600 mA Gain - 10.5 - dB Noise Figure - 3.0 - dB Output Power - +20 - dBm OIP31 - +52 - dBm P1dB - +31 - dBm NOTE: 1. Measured using two CW tones at an output power level of +20 dBm per tone. Table 4: 450 MHz 8 V PARAMETER MIN TYP MAX UNITS Frequency 350 450 500 MHz VDD - 8 - VDC IDD 400 425 600 mA Gain - 10.5 - dB Noise Figure - 3.0 - dB Output Power - +16 - dB OIP31 - +16 - dBm P1dB - +28 - dBm NOTE: 1. Measured using two CW tones at an output power level of +16 dBm per tone. 6 Application Note - Rev 0 06/2010 ADAPTING THE ACA0861C FOR 50 V OPERATION +Vdd C7 0.01uF L1 11nH RF IN (50-ohms) C2 27pF U1 C5 33pF 14 L5 5.1nH RF OUT (50-ohms) ACA0861C C1 7.5pF 11 6 C3 0.01uF R1 1.3ohm 15 3 10 7 L6 180nH L2 33nH R2 47ohm C4 0.7pF C8 0.01uF R5 20k C6 8.2pF L4 10nH L3 22nH R4 1.3ohm R3 3.9ohm +Vdd Figure 8: 450 MHz Circuit Figure 9: 450 MHz S21 Graph 11 10 9 8 S21 (dB) 7 6 5 4 3 2 1 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 Frequency (MHz) Application Note - Rev 0 06/2010 7 ADAPTING THE ACA0861C FOR 50 V OPERATION Figure 10: 450 MHz S11, S12, S22 Graph 0 S11, S12, S22 (dB) -5 -10 -15 -20 S12 S22 -25 S11 -30 0 100 200 300 400 500 600 700 800 Frequency (MHz) 65.0 Figure 11: Typical OIP3 (20 dBm POUT) vs IDD @ 12 V (450 MHz) Typical OIP3 (16 dBm POUT) vs IDD @ 8 V (450 MHz) 60.0 55.0 OIP3 (dBm) Vdd = +12Vdc 50.0 Pout = +20dBm/tone 45.0 Vdd = +8Vdc 40.0 Pout = +16dBm/tone 35.0 30.0 400 450 500 Idd (mA) 8 Application Note - Rev 0 06/2010 550 600 ADAPTING THE ACA0861C FOR 50 V OPERATION Table 5: 950 MHz 12 V PARAMETER MIN TYP MAX UNITS Frequency 850 950 1150 MHz VDD - 12 - VDC IDD 400 450 500 mA Gain - 10.5 - dB Noise Figure - 3.0 - dB Output Power - +16 - dBm OIP31 - +58 - dBm P1dB - +26.5 - dBm NOTES: 1. Measured using two CW tones at an output power level of +16dBm per tone. Table 6: 950 MHz 8 V PERFORMANCE MIN TYP MAX UNITS Frequency 850 950 1150 MHz VDD - 8 - VDC IDD 350 400 450 mA Gain - 10.5 - dB Noise Figure - 3.0 - dB Output Power - +13 - dBm OIP31 - +42 - dBm P1dB - +23.5 - dBm NOTES: 1. Measured using two CW tones at an output power level of +13 dBm per tone. Application Note - Rev 0 06/2010 9 ADAPTING THE ACA0861C FOR 50 V OPERATION +Vdd C5 0.01uF RF IN (50-ohms) L2 3.3nH C1 2.7pF L3 3.3nH 14 11 6 10 7 R2 10ohm R1 4.7ohm U1 ACA0861C C2 1pF L1 8.2nH 15 3 L5 180nH L6 ~1nH R3 10ohm L4 9.5nH R4 4.7ohm C7 0.7pF C6 0.01uF R5 20k C3 1pF 0.5T 0.2in dia #20AwG RF OUT (50-ohms) C4 2.7pF +Vdd Figure 12: 950 MHz Circuit Figure 13: 950 MHz S21 Graph 12 11 10 9 S21 (dB) 8 7 6 5 4 3 2 1 400 500 600 700 800 900 1000 Frequency (MHz) 10 Application Note - Rev 0 06/2010 1100 1200 1300 1400 1500 ADAPTING THE ACA0861C FOR 50 V OPERATION Figure 14: 950 MHz S11, S12, S22 Graph 0 -5 -10 S11 (dB) -15 -20 S12 -25 S22 -30 -35 S11 -40 -45 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Frequency (MHz) Figure 15: Typical OIP3 (16 dBm POUT) vs IDD @ 12 V (950 MHz) Typical OIP3 (13 dBm POUT) vs IDD @ 8 V (950 MHz) 60.0 Vdd = +12Vdc Pout = 16dBm OIP3 (dBm) 55.0 50.0 45.0 Vdd = +8Vdc Pout = 13dBm 40.0 35.0 300 325 350 375 400 425 450 475 500 Idd (mA) Application Note - Rev 0 06/2010 11 ADAPTING THE ACA0861C FOR 50 V OPERATION Reduced Current Consumption The total power dissipation may be reduced in exchange for a slight degradation in the linearity performance. Reductions in current have no effect on the Gain (S21). The overall current consumption of the device is controlled by the magnitude of the voltage across pin #7. The relationship between the VBIAS and the Current Consumption is depicted in the graph below. The performance is characterized at a nominal VBIAS of +1.0 VDC at 12 VDD. Figure 15: IDD vs VBIAS @ 8 V & 12 V 650 12V 600 8V Idd (mA) 550 500 450 400 350 0.5 0.6 0.7 0.8 0.9 1.0 Vbias (Vdc) 12 Application Note - Rev 0 06/2010 1.1 1.2 1.3 1.4 ADAPTING THE ACA0861C FOR 50 V OPERATION Figure 16: Bias Resistor vs IDD @ 8 V & 12 V 900 800 Idd (mA) 700 600 12V 500 400 8V 300 200 0 10 20 30 40 50 60 70 80 90 100 Bias Resistor (K-ohms) Assembly/Mounting and Thermal Considerations The ACA0861C, under normal biasing conditions, dissipates approximately 5Watts of power and is capable of dissipating in excess of 8Watts under aggressive biasing. Therefore, proper soldering of the heat slug, located on the bottom surface of the package, is critical. A comprehensive description of the recommended layout, mounting, and thermal considerations is presented in the ANADIGICS Application Note “ACA0861-A,B,C,D 750/860MHz CATV Line Amplifiers”. This document is available for downloading from the ANADIGICS website at: http://www.anadigics.com/content/download/323/1338/version/2/file/ACA0861.pdf Application Note - Rev 0 06/2010 13 ADAPTING THE ACA0861C FOR 50 V OPERATION ANADIGICS 141 Mount Bethel Road Warren, New Jersey 07059, U.S.A. Tel: +1 (908) 668-5000 Fax: +1 (908) 668-5132 URL: http://www.anadigics.com IMPORTANT NOTICE ANADIGICS, Inc. reserves the right to make changes to its products or to discontinue any product at any time without notice. The product specifications contained in Advanced Product Information sheets and Preliminary Data Sheets are subject to change prior to a product’s formal introduction. Information in Data Sheets have been carefully checked and are assumed to be reliable; however, ANADIGICS assumes no responsibilities for inaccuracies. ANADIGICS strongly urges customers to verify that the information they are using is current before placing orders. warning ANADIGICS products are not intended for use in life support appliances, devices or systems. Use of an ANADIGICS product in any such application without written consent is prohibited. 14 Application Note - Rev 0 06/2010