DEMO MANUAL DC2078A LTC6430-20 50MHz TO 1000MHz 75 INPUT/OUTPUT CATV AMPLIFIER DESCRIPTION Demonstration circuit 2078A is a 75 input and 75 output push-pull CATV amplifier featuring the LTC(R)643020. The LTC6430-20 has a power gain of 20.8dB and is part of the LTC6430-YY amplifier series. The DC2078A demo board is optimized for the frequency range from 50MHz to 1000MHz. It incorporates a minimum of passive support components to configure the amplifier for the CATV applications with 75 input and output impedance. Design files for this circuit board are available at http://www.linear.com/demo/DC2078A L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. LTC6430-20 BLOCK DIAGRAM VCC 9, 22 BIAS AND TEMPERATURE COMPENSATION 24 +IN 20dB GAIN +OUT T_DIODE 7 -IN 20dB GAIN -OUT 18 16 13 GND 8, 14, 17, 23 AND PADDLE 25 643020 BD dc2078af 1 DEMO MANUAL DC2078A PERFORMANCE SUMMARY TA = 25C, VCC = 5V Table 1. Typical Demo Board Performance Summary SYMBOL PARAMETER CONDITIONS VALUE/UNIT VCC Operating Supply Range All VCC Pins Plus OUT 4.75V to 5.25V ICC Current Consumption Total Current 170mA Power Supply FREQUENCY (MHz) POWER GAIN |S21| OUTPUT THIRDORDER INTERCEPT POINT1 OIP3 OUTPUT THIRDORDER INTERMODULATION1 OIM3 SECOND HARMONIC DISTORTION2 HD2 THIRD HARMONIC DISTORTION2 HD3 OUTPUT 1DB COMPRESSION POINT P1DB NOISE FIGURE3 NF 50 19.1 46.5 -91.0 -86.4 -87.6 22.3 3.5 100 19.1 46.7 -91.4 -86.6 -82.7 22.6 3.5 200 19.1 45.6 -89.3 -82.2 -79.0 22.8 3.5 240 19.1 44.5 -86.9 -80.8 -78.2 22.9 3.4 300 19.1 43.7 -85.4 -73.4 -72.9 23.4 3.4 400 19.3 44.1 -86.2 -66.6 -73.2 24.0 3.4 500 19.4 46.8 -91.6 -62.6 24.2 3.5 600 19.2 47.0 - 92.0 24.3 3.8 700 18.8 46.3 -90.6 23.7 4.3 800 18.5 43.7 -85.4 22.8 4.7 900 18.4 41.9 -81.9 22.5 5.0 1000 18.5 41.5 -81.0 22.7 5.0 Units dB dBm dBc dBm dB dBc dBc Notes: All figures are referenced to J1 (Input Port) and J4 (Output Port). 1. Two-tone test conditions: Output power level = +1dBm/tone, tone spacing = 1MHz. 2. Single-tone test conditions: Output power level = +6dBm. 3. Small-signal noise figure. dc2078af 2 DEMO MANUAL DC2078A OPERATION Demo circuit 2078A is a high linearity, fixed gain amplifier. To configure the demo circuit 2078A for use in the 75 CATV environment, a transformer with 1:1.33 impedance ratio is added at the board's input and output. These transformers transform the differential 100 impedance of the LTC6430-20 to single-ended 75 impedance. The frequency range of the circuits is limited by the balun transformers. Hence, the demo board has a nominal working frequency range from 50MHz to 1000MHz. Figure 2 shows the S-parameters of demo board. Demo circuit 2078A is shipped with 75 F-type connectors (J1 and J2) at both input and output. Depending on the user's preference, the board may also accept other connector types such as BNC or SMA. Please note that the use of substandard connectors can limit the usable bandwidth of the circuit. The input and output transformers (T3 and T4) convert the differential signal to single-ended 75 signal for compatibility with the CATV environment, while preserving all the exceptional characteristics of the LTC6430-20. In addition, the balun's excellent phase balance and the second order linearity of the LTC6430-20 combine to further suppress second order products across the entire CATV band. Figure 3 shows the spurious products (in dBc) within the passband frequency 50MHz to 1000MHz. The output thirdorder intermodulation (OIM3) and the second harmonic distortion (HD2) are shown as a function of frequency. Frequency appropriate chokes (L1 and L2) and the decoupling capacitors (C9, C10, C11 and C12) provide bias to the RF OUT nodes. Only a single 5V supply is necessary for the VCC pins on the device. Table 2. DC2078A Board I/O Descriptions CONNECTOR J1 (IN) |S21| 20 E1 (VCC) E2 (GND) E3 (T_DIODE) In this particular application circuit, the input stability networks (C3, C4, R1, R2) are not required since the LTC6430-20 is preceded by a low frequency termination from the balun transformer. In a wideband differential application where the bandwidth extends below 20MHz, the input stability network is suggested. 0 -4 -16 14 12 -20 |S11| 10 8 -24 -28 |S12| -20 OIM3, HD2 (dBc) -12 |S11|, |S12|, |S22| (dB) |S22| 16 -30 -40 -50 -60 -70 6 -32 4 -36 -80 2 -40 -90 -44 1240 -100 0 40 240 440 640 840 FREQUENCY (MHz) 1040 DC2078a F02 OIM3, POUT = 1dBm/TONE HD2, POUT = 6dBm -10 -8 18 FUNCTION Single-Ended Input. Impedance Matched to 75. Single-Ended Output. Impedance Matched to 75. Positive Supply Voltage Source. Negative Supply Ground. The measured voltage will be an indicator of the chip junction temperature. J2 (OUT) 0 22 |S21| (dB) The input and output DC blocking capacitors (C1, C2, C7 and C8) are required because this device is internally biased for optimal operation. HD2 OIM3 0 200 600 400 FREQUENCY (MHz) 800 1000 DC2078a F03 Figure 2. Demo Board S-Parameters Figure 3. OIM3 and HD2 vs Frequency dc2078af 3 DEMO MANUAL DC2078A OPERATION L3, L4, C19 and C20 are optional parts. They are for additional matching components when further optimization to a lower or wider frequency range applications is required. Table 2 shows the function of each input and output on the board. Additional Information As with any RF device, minimizing ground inductance is critical. Care should be taken with the board layout because of the exposed pad packages. The maximum number of minimum diameter vias holes should be placed underneath the exposed pad. This will ensure good RF ground and low thermal impedance. Maximizing the copper ground plane will also improve heat spreading and lower the inductance to ground. It is a good idea to cover the via holes with solder mask on the back side of the PCB to prevent solder from wicking away from the critical PCB to the exposed pad interface. Please note that a number of DNC pins are connected on the demo board. These connections are not necessary for normal operation, however, failure to float these pins may impair the operation of the device. Table 3 shows the LTC643X-YY amplifier series and its associated demo boards. Each demo board lists the typical working frequency range and the input and output impedance of the amplifiers. Setup Signal Sources and Spectrum Analyzer The LTC6430-20 is an amplifier with high linearity performance. Therefore, the output intermodulation products are very low. Even using high dynamic range test equipment, Third-Order Intercept (IP3) measurements can drive test setups to their limits. Consequently, accurate measurement of IP3 for a low distortion IC such as the LTC6430-20 requires certain precautions to be observed in the test setup as well as in the testing procedure. The T_DIODE Pin (Turret E3) can be forward biased to ground with 1mA of current. The measured voltage will be an indicator of the chip junction temperature (TJ). Table 3. The LTC643X-YY Amplifier Family and Corresponding Application Demo Boards FREQUENCY RANGE (MHz) NOTES/APPLICATIONS BOARD'S IN/OUT IMPEDANCE AMPLIFIER AMPLIFIER'S IMPEDANCE DC1774A-A 50 to 350 Low Frequency 50 LTC6430-15 Differential 100 DC1774A-B 400 to 1000 Mid Frequency 50 LTC6430-15 Differential 100 DC1774A-C 100 to 1200 Wide Frequency 50 LTC6431-15 Single-ended 50 DC2032A 50 to 1000 Cable Infrastructure 75 LTC6430-15 Differential 100 DC2077A 100 to 1200 Wide Frequency 50 LTC6431-20 Single-ended 50 DC2153A 700 to 1700 High Frequency 50 LTC6430-15 Differential 100 DEMO BOARD NUMBER DC2090A 50 to 1200 Power Doubler 50 Dual LTC6430-15 Differential 50 DC2076A-A 50 to 350 Low Frequency 50 LTC6430-20 Differential 100 DC2076A-B 350 to 1000 Mid Frequency 50 LTC6430-20 Differential 100 DC2078A 50 to 1000 Cable Infrastructure 75 LTC6430-20 Differential 100 dc2078af 4 DEMO MANUAL DC2078A OPERATION Setup Signal Sources Setup the Spectrum Analyzer Figure 4 shows a proposed IP3 test setup. This setup has low phase noise, good reverse isolation, high dynamic range, sufficient harmonic filtering and wideband impedance matching. The setup is outlined below: a. Adjust the spectrum analyzer for maximum possible resolution of the intermodulation products' amplitude in dBc. A narrower resolution bandwidth will take a longer time to sweep. a. High performance signal generators 1 and 2 (HP8644A) are used. These suggested generators have low harmonic distortion and very low phase noise. b. Optimize the dynamic range of the spectrum analyzer by adjusting the input attenuation. First increase the spectrum analyzer's input attenuation (normally in steps of 5dB or 10dB). If the IM product levels decrease when the input attenuation is increased, then the input power level is too high for the spectrum analyzer to make a valid measurement. Most likely, the spectrum analyzer's 1st mixer was overloaded and producing its own IM products. If the IM reading holds constant with increased input attenuation, then a sufficient amount of attenuation was present. Adding too much attenuation will bury the intended IM signal in the noise floor. Therefore, select just enough attenuation to achieve a stable and valid measurement. b. High linearity amplifiers are used to improve the reverse isolation. This prevents cross talk between the two signal generators and provides higher output power. c. A low pass filter is used to suppress the harmonic content from interfering with the test signal. Note that second order inputs can "mix" with the fundamental frequency to form intermodulation (IM) products of their own. We suggest filtering the harmonics to -50dBc or better. d. The signal combiner from Mini-Circuits (ADP-2-9) combines the two isolated input signals. This combiner has a typical isolation of 27dB. For improved VSWR and isolation, the H-9 signal combiner from MA/COM is an alternative which features >40dB isolation and a wider frequency range. Passive devices (e.g. combiners) with magnetic elements can contribute nonlinearity to the signal chain and should be used cautiously. e. The attenuator pads on all three ports of the signal combiner will further support isolation of the two input signal sources. They also reduce reflections and promote maximum power transfer with wideband impedance matching. c. In order to achieve this valid measurement result, the test system must have lower total distortion than the DUT's intermodulation. For example, to measure a 47dBm OIP3, the measured intermodulation products will be -92dBc below an -18dBm/tone input level and the test system must have intermodulation products approximately -98dBc or better. For best results, the IM products and noise floor should measure at least -102dBc before connecting the DUT. dc2078af 5 DEMO MANUAL DC2078A QUICK START PROCEDURE Demo circuit 2078A can be set up to evaluate the performance of the LTC6430-20. Refer to Figure 4 for proper equipment connections and follow the procedure below: Two-Tone Measurement: Connect all test equipment as suggested in Figure 4. 1. The power labels of "VCC 4.75V-5.25V" and GND directly correspond to the power supply. Typical current consumption of the LTC6430-20 is about 170mA. 2. Apply two independent signals f1 and f2 from signal generator 1 and signal generator 2 at 600MHz and 601MHz, while setting the amplitude to -18dBm/tone at the demo board input (J1). 3. Monitor the output tone level on the spectrum analyzer. Adjust the signal generator levels such that the output power measures +1dBm/tone at the amplifier output J2, after correcting for external cable losses, minimum loss matching pads and attenuations. 4. Change the spectrum analyzer's center frequency and observe the two IM3 tones at 1MHz below and above the input frequencies. The frequencies of IM3_LOW and IM3_HIGH are 599MHz and 602MHz, respectively. The measurement levels should be approximately -92dBc; +47dBm is typical OIP3 performance for the LTC643020 at 600MHz. The OIP3 calculation is: OIP3 = POUT + IMD3/2 Where: POUT is the lower output signal power of the fundamental products. IMD3 = POUT - PIM3; PIM3 is the higher Third-Order intermodulation product. Single-tone Measurement 5. Continue with step 4 above, turn off one signal source to measure gain and harmonic distortions. dc2078af 6 DEMO MANUAL DC2078A QUICK START PROCEDURE SIGNAL GENERATOR 1 (HP8644A) AMPLIFIER MINI-CIRCUITS, ZHL-2 OR EQUIVALENT 20dB ATTENUATION PAD (MATCHES DUT GAIN) LOW PASS FILTER DUT GAIN APPROX. 19dB 3dB ATTENUATION PAD 6dB ATTENUATION PAD (OPTIONAL) 1dBm/TONE COAXIAL CABLE -5.7dB -5.7dB COMBINER MINI-CIRCUITS ADP-2-9 OR EQUIVALENT 50 6dB ATTENUATION PAD (OPTIONAL) LOW PASS FILTER AMPLIFIER MINI-CIRCUITS, ZHL-2 OR EQUIVALENT SIGNAL GENERATOR 2 MINIMUM LOSS MATCHING PAD MINIMUM LOSS MATCHING PAD 75 75 MINI-CIRCUITS BMP-5075R OR EQUIVALENT MINI-CIRCUITS BMP-5075R OR EQUIVALENT APPROX. -12dBm/TONE 50 APPROX. -18dBm/TONE DC POWER SUPPLY GND SPECTRUM ANALYZER ROHDE AND SCHWARZ FSEM30 DC2078a F04 VCC = 4.75V TO 5.25V V+ (HP8644A) Figure 4. Proper Equipment Setup for IP3 Measurement dc2078af 7 DEMO MANUAL DC2078A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART # 1 4 C1, C2, C7,C8 CAP., X5R, 0.047F, 25V 10%, 0603 AVX, 06033D473KAT2A 2 0 C3, C4, C19, C20 3 2 C5, C6 CAP., X7R, 1000pF, 50V 5%, 0402 AVX, 04025C102JAT2A 4 2 C9, C11 CAP., X5R, 0.1F, 10V, 10%, 0603 AVX, 0603ZD104KAT2A 5 2 C10, C12 CAP., X7R, 1000pF, 50V 5%, 0603 AVX, 06035C102JAT2A 6 3 E1, E2, E3 TESTPOINT, TURRET, 0.095" MILL-MAX, 2501-2-00-80-00-00-07-0 7 2 J1, J2 F TYPE END LAUNCH JACK FOR 0.062" PCB, 75 AMPHENOL CONNEX, 222181 8 2 L1, L2 INDUCTOR, CHIP, 560nH, 5%, 0603LS-1608 COILCRAFT, 0603LS-561XJLB 9 2 L3,L4 RES., CHIP, 0, 0603 VISHAY, CRCW06030000Z0ED 10 2 R1,R2 RES., CHIP, 0, 0603 VISHAY, CRCW06030000Z0ED 11 1 R3 12 2 T3, T4 RF TRANSFORMER TC1.33-282+, CASE STYLE: AT224-1 MINI-CIRCUITS, TC1.33-282+ 13 1 U1 BALANCED AMPLIFIER LTC6430AIUF-20, QFN24UF-4X4 LINEAR TECH., LTC6430AIUF-20 CAP., 0603, OPT R-0402, OPT dc2078af 8 Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. A B C D 5 4 4 3 3 5 2 1 1 CATV AMPLIFIER TECHNOLOGY 2 A B C D DEMO MANUAL DC2078A SCHEMATIC DIAGRAM dc2078af 9 DEMO MANUAL DC2078A DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user's responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright (c) 2004, Linear Technology Corporation dc2078af 10 Linear Technology Corporation LT 1014 * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com LINEAR TECHNOLOGY CORPORATION 2014