DEMO MANUAL DC1774A-C LTC6431-15 50Ω Gain Block IF Amplifier DESCRIPTION Demonstration circuit 1774A-C is a 50Ω gain block IF amplifier featuring the LTC®6431-15. It is part of the DC1774A demo board family supporting the LTC643XYY amplifier series. The DC1774A-C is optimized for a frequency range of 100MHz to 1200MHz and utilizes a minimum of passive external components to configure the amplifier for this application. PERFORMANCE SUMMARY Because the LTC6431-15 has 50Ω single-ended input and output impedance, the demo circuit can be connected directly to most commercially available RF test equipment for the evaluation. Design files for this circuit board are available at http://www.linear.com/demo 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. Specifications are at TA = 25°C, VCC = 5V Table 1. Typical Demo Board Performance Summary SYMBOL PARAMETER CONDITIONS VALUE/UNIT VCC Operating Supply Range All VCC Pins Plus +OUT ICC Current Consumption Total Current Power Supply 4.75V to 5.25V 90mA OUTPUT THIRD-ORDER INTERMODULATION 1 OIM3 (dBc) SECOND HARMONIC DISTORTION 2 HD2 (dBc) THIRD HARMONIC DISTORTION 2 HD3 (dBc) OUTPUT 1dB COMPRESSION POINT NOISE FIGURE 3 P1dB NF (dBm) (dB) FREQUENCY (MHz) POWER GAIN S21 (dB) OUTPUT THIRD-ORDER INTERCEPT POINT 1 OIP3 (dBm) 100 15.1 46.6 –89.2 –58.0 –88.0 20.0 3.8 200 15.4 46.7 –89.5 –58.0 –88.0 20.0 3.5 240 15.6 46.7 –89.3 –59.0 –88.0 20.3 3.4 300 15.5 46.6 –89.3 –60.0 –86.0 20.1 3.5 400 15.5 46.1 –88.3 –57.0 –87.0 20.3 3.5 500 15.4 45.3 –86.6 –55.6 –77.0 20.3 3.6 600 15.3 43.5 –83.1 –53.6 –69.0 20.4 3.7 700 15.2 42.2 –80.4 –51.9 –69.0 20.2 3.8 800 15.0 41.1 –78.1 –49.2 –65.0 20.1 4.0 900 14.8 39.5 –74.9 –46.7 –63.0 19.7 4.2 1000 14.7 38.7 –73.3 –45.0 –59 19.3 4.2 1100 14.5 38.0 –71.9 –40.8 –56.8 18.8 4.4 1200 14.3 38.0 –71.9 –38.4 –54.2 18.6 4.6 Notes: All measurements are referenced to J7 (Input Port) and J10 (Output Port). 1. Two-tone test condition: Output power level = +2dBm/tone; Tone spacing = 1MHz. 2. Single-tone test condition: Output power level = +6dBm. 3. Small-signal noise figure. dc1774acfa 1 DEMO MANUAL DC1774A-C QUICK START PROCEDURE Demo circuit 1774A-C can be set up to evaluate the performance of the LTC6431-15. Refer to Figures 4 and 5, for proper equipment connections and follow the procedure below: Single-Tone Measurement: Connect all test equipment as suggested in Figure 4. 1.The power labels of +5V and GND directly correspond to the power supply. Typical current consumption of the LTC6431-15 is about 90mA. 2.Apply an input signal to J7. A low-distortion, low noise signal source with an external high order lowpass filter will yield the best performance. The input signal is –10dBm. 3.Observe the output via J10. The measured power at the analyzer should be about +5dBm. VCC (PINS 9, 22) BIAS AND TEMPERATURE COMPENSATION IN (PIN 24) T-DIODE (PIN 16) Two-Tone Measurement: Connect all test equipment as suggested in Figure 5. 1.The power labels of +5V and GND directly correspond to the power supply. Typical current consumption of the LTC6431-15 is about 90mA. 2.Apply two independent signals f1 and f2 from SG1 and SG2 at 240MHz and 241MHz respectively. 3.Monitor the output tone level on the spectrum analyzer. Adjust signal generator levels such that output power measures +2dBm/tone at the amplifier output J10, after correcting for external cable losses and attenuators. 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 239MHz and 242MHz, respectively. For this setup, the Rohde and Schwarz FSEM30 spectrum analyzer was used. This spectrum analyzer has a typical 20dBm third-order intercept point (TOI). The Rohde and Schwarz FSU can also be used. The system as described can measure OIP3 up to 50dBm. OUT (PIN 18) GND (PINS 8, 17, 23 AND EXPOSED PAD 25) dc1774ac F01 Figure 1. LTC6431-15 Device Block Diagram dc1774acfa 2 DEMO MANUAL DC1774A-C QUICK START PROCEDURE NOMINAL WORKING FREQUENCY RANGE 18 16 5 |S21| (dB) 14 4 12 10 8 6 4 0 |S11|, |S12|, |S22| (dB) 0 –2 –4 –6 |S21| –8 –10 –12 |S22| 3 –14 |S11| –16 –18 –20 –22 |S12| –24 –26 –28 400 1200 2000 800 1600 FREQUENCY (MHz) 2 1 ECO __ REV 2 REVISION HISTORY DESCRIPTION PRODUCTION APPROV JOHN C dc1774ac F02 Figure 2. Demo Board S-Parameters Stability Network C8 62pF C1 1000pF VCC R2 348 U1 *1 4 DNC U1=LTC6431-15 5 +OUT 0603 N/C N/C VCC J11 12 N/C 11 VCC 10 9 GND 8 DNC GND J10 R17 0 GND 14 DNC 13 DNC 6 DNC GND C21 1000pF T_DIODE 16 DNC 15 7 E6 C22 0.1uF C3 1000pF +OUT 18 GND 17 DNC 2 DNC 3 DNC J18 L1 560nH DNC 19 0603 DNC 21 DNC 20 0 +IN 24 GND 23 VCC 22 R13 GND 25 J7 +IN VCC C7 1000pF E3 +5V +5V C20 1000pF Figure 3. Simplified Demo Board DC1774A-C Schematic CUSTOMER NOTICE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 5 4 3 APPROVALS PCB DES. KIM T. APP ENG. JOHN C. TECHNOLOGY TITLE: SCHEMATIC SIZE N/A SCALE = NONE 2 DATE: 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 w Fax: (408)434-0507 LTC Confidential-For Cus IF AMP/ADC DRIVER IC NO. LTC643XIUF FAMILY DEMO CIRCUIT 1774A-C Monday, July 16, 2012 dc1774acfa 3 1 SHEE DEMO MANUAL DC1774A-C OPERATION The demo circuit 1774A-C is a high linearity fixed gain amplifier. It is designed for ease of use. Both the input and output are internally matched to 50Ω single-ended source and load impedance which is compatible with most test equipment. Figure 2 shows the demo board S-parameters. Figure 3 shows the demo circuit schematic. It requires a minimum of passive support components. The input and output DC blocking capacitors (C1 and C3) are required because this device is internally biased for optimal operation. The frequency appropriate choke (L1) and the decoupling capacitors (C21 and C22) provide bias to the RF +OUT node. Only a single 5V supply is necessary for the VCC pins on the device. An optional input stability network has been added. It consists of a parallel 62pF (C8) and 348Ω (R2) input network has been added to insure low frequency stability. Table 2 shows the function of each input and output on the board. Table 2. DC1774A-C Board I/O Descriptions CONNECTOR FUNCTION J7 (+IN) Single-Ended Input. Impedance Matched to 50Ω. Drive from a 50Ω Network Analyzer or Signal Source. J10 (+OUT) Single-Ended Output. Impedance Matched to 50Ω. Drive from a 50Ω Network Analyzer or Spectrum Analyzer. E3 or J11 (VCC) Positive Supply Voltage Source. E6 or J18 (GND) Negative Supply Ground. ADDITIONAL INFORMATION The particular element values shown in the demo board schematic are chosen for wide bandwidth operation. Depending on the desired frequency, performance may be improved by the proper selection of these supporting components. As with any RF device, minimizing ground inductance is critical. Care should be taken with the board layout because of these 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 reduce inductance. 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. The DC1774A-C is a wide bandwidth demo board but it is not intended for operation down to DC. The lower frequency cutoff is limited by on-chip matching elements. Figure 6 shows the generic PCB schematic for the LTC643X‑YY amplifier series. The board can be modified for multiple demo board versions. For example, both DC1774A-A and DC1774A-B demo boards have a differential amplifier at U1; therefore, the board is using transformers to transform from differential to single-ended input and output. Likewise, the DC1774A-C is a singleended demo board; consequently, it uses the LTC6431-15 for single-ended input and output. Setup and Testing Signal Sources The LTC6431-15 is an amplifier with high linearity performance, therefore output intermodulation products are very low. For this reason, it drives most test equipment and test setups to their limits. Consequently, accurate measurement of the third-order intercept point for a low distortion IC such as the LTC6431-15 requires certain precautions to be observed in the test setup and testing procedure. Setup Signal Source Figure 5 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: 1.High performance signal generators 1 and 2 (HP8644A) were used in the setup. These suggested generators have low harmonic distortion and very low phase noise. dc1774acfa 4 DEMO MANUAL DC1774A-C ADDITIONAL INFORMATION 2.High linearity amplifiers to improve isolation. It prevents the two signal generators from crosstalking with each other and provides higher output power. 3.A lowpass filter to suppress the harmonic contents from interfering with the test signal. 4.The signal combiner from Mini-Circuits ADP-2-9 combines the two isolated input signals. This combiner has a typical isolation of 27dB. For better VSWR and isolation, use the H-9 signal combiner from MA/COM which features >40dB isolation and a wider frequency range. Passive devices (e.g., combiners) with magnetic elements can contribute no-linearity to the signal chain and should be used cautiously. input attenuation is increased, then the input power level was too high for the spectrum analyzer to make a valid measurement. In other words, the spectrum analyzer 1st mixer was overloaded and producing its own IMD products. If the IMD reading holds constant with increased input attenuation, then a sufficient amount of attenuation was present. Adding too much attenuation will raise the noise floor and bury the intended IMD signal. Therefore, select just enough attenuation to achieve a stable and valid measurement. 5.The attenuator pads on all three ports of the signal combiner will support further isolation of the two input signal sources. They will reduce reflection and promote maximum power transfer with wideband impedance matching. d.In order to achieve a valid measurement result, the test system must have lower distortion than the DUT intermodulation. For example, to measure a +47dBm OIP3, the measured intermodulation products will be –90dBc below the –13dBm per tone input level and the test system must have Intermodulation products approximately –96dBc or better. For best results, the IMD or noise floor should be at least –100dBc before connecting the DUT. Testing Signal Sources Testing the DUT The testing signal should be evaluated and optimized before it is used for measurements. The following outlines the necessary steps to achieve optimization: At this point, the input level has been established at –13dBm per tone, and the input IMD from the test setup is well suppressed at –96dBm max. Furthermore, the spectrum analyzer is setup to measure very low level IMD components. a. Apply two independent signals f1 and f2 from signal generator 1 and signal generator 2 at 240MHz and 241MHz while setting amplitude = –13dBm per tone at the combined output. b.Connect the combined signal directly to the spectrum analyzer (without the DUT). c. Adjust the spectrum analyzer for the maximum possible resolution of the intermodulation products amplitude in dBc relative to the main tone power. A narrower resolution bandwidth will take a longer time to sweep. Optimize the dynamic range of the spectrum analyzer by adjusting input attenuation. First increase the spectrum analyzer input attenuation (normally in steps of 5dB or 10dB). If the IMD product levels decrease when the a. Insert the DUT and output attenuator into the setup, inline between the signal source and the spectrum analyzer. The output attenuator should match the DUT gain. b.Fine tune the signal generator levels by a small amount if necessary (<1dB), to keep output power at +2dBm per tone at the amplifier output. c. Measure the output IMD level using the same optimized setup as previous. Based on the output power level of +2dBm per tone, and knowing the IMD level, OIP3 can be calculated. dc1774acfa 5 DEMO MANUAL DC1774A-C ADDITIONAL INFORMATION SIGNAL GENERATOR ASSY U1 FREQ -A LTC6430AIUF-15 100MHz TO 300MHz -B LTC6430AIUF-15 400MHz TO 1000MHz -C LTC6431AIUF-15 100MHz TO 1200MHz DC POWER SUPPLY GND V+ (HP8644A) COAXIAL CABLE SPECTRUM ANALYZER LOWPASS FILTER (OPTIONAL) 3dB ATTENUATION PAD (OPTIONAL) ROHDE AND SCHWARZ FSEM30 Figure 4. Proper Equipment Setup for Gain and Single-Tone Measurement dc1774acfa 6 DEMO MANUAL DC1774A-C ADDITIONAL INFORMATION SIGNAL (HP8644A) GENERATOR 1 ASSY U1 FREQ -A LTC6430AIUF-15 100MHz TO 300MHz -B LTC6430AIUF-15 400MHz TO 1000MHz -C LTC6431AIUF-15 100MHz TO 1200MHz DC POWER SUPPLY GND V+ AMPLIFIER (MINI-CIRCUITS, ZHL-2 OR EQUIVALENT) LOWPASS FILTER 6dB ATTENUATION PAD (OPTIONAL) COAXIAL CABLE COMBINER MINI CIRCUIT ADP-2-9 SPECTRUM ANALYZER 3dB ATTENUATION 6dB ATTENUATION PAD PAD (OPTIONAL) APPROXIMATELY –13dBm/TONE 2dBm/TONE ROHDE AND SCHWARZ FSEM30 15dB ATTENUATION PAD (MATCHES DUT GAIN) LOWPASS FILTER AMPLIFIER (MINI-CIRCUITS, ZHL-2 OR EQUIVALENT) DUT GAIN APPROXIMATELY 15dB SIGNAL (HP8644A) GENERATOR 2 Figure 5. Proper Equipment Setup for IP3 Measurement dc1774acfa 7 DEMO MANUAL DC1774A-C PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER CAP., X7R, 1000pF, 50V 5%, 0402 AVX, 04025C102JAT2A DC1774A2 Required Circuit Components 1 4 C1, C3, C7, C20 2 1 C21 CAP., X7R, 1000pF, 50V 5%, 0603 AVX, 06035C102JAT2A 3 1 C8 CAP., COG, 62pF, 16V 2%, 0402 AVX, 0402YA620GAT2A 4 0 C10, C12 CAP., COG, 62pF, 16V 2%, 0402 OPT 5 0 C11, C13, C16-C19 CAP., X7R, 1000pF, 5%, 0402 OPT 6 1 C22 CAP., X5R, 0.1µF, 10V, 10%, 0603 AVX, 0603ZD104KAT2A 7 2 E3, E6 TESTPOINT, TURRET, 0.064" MILL-MAX, 2308-2-00-80-00-00-07-0 8 0 JP1 HEADER, 2X6, 0.1" OPT 9 0 JP2, JP3 HEADER, 2X4, 0.1" OPT 10 0 J5, J6 CONN., SMA 50Ω EDGE-MOUNTED OPT 11 1 J7 CONN., SMA 50Ω EDGE-MOUNTED JOHNSON, 142-0701-851 12 0 J9 CONN., SMA 50Ω EDGE-MOUNTED OPT 13 2 J11, J18 JACK, BANANA KEYSTONE, 575-4 14 1 L1 INDUCTOR, CHIP, 560nH, 5%, 0603LS-1608 COILCRAFT, 0603LS-561XJLB 15 0 L11, L22 INDUCTOR, CHIP, 1008LS-2520 OPT 16 1 R2 RES., CHIP, 348Ω, 1%, 0402 YAGEO, RC0402FR-07348RL 17 0 R5, R6 RES., CHIP, 348Ω, 1%, 0402 OPT 18 0 R19 RES., CHIP, 0Ω, 5%, 0402 YAGEO, RC0402JR-070RL DC1774A2-C Required Circuit Components 1 1 DC1774A-2 GENERAL BOM 2 0 C2, C4 CAP., X7R, 1000pF, 50V 5%, 0402 AVX, 04025C102JAT2A 3 0 C5 CAP., X7R, 1000pF, 50V 5%, 0603 AVX, 06035C102JAT2A 4 0 C9 CAP., COG, 62pF, 16V 2%, 0402 AVX, 0402YA620GAT2A 5 0 C14, C15 CAP., X7R, 1000pF, 25V 5%, 0402 AVX, 04023C102JAT2A 6 0 C23 CAP., X5R, 0.1µF, 10V, 10%, 0603 AVX, 0603ZD104KAT2A 7 0 L2 INDUCTOR, CHIP, 560nH, 5%, 0603LS-1608 COILCRAFT, 0603LS-561XJLB 8 0 J8 CONN., SMA 50Ω EDGE-MOUNTED OPT 9 1 J10 CONN., SMA 50Ω EDGE-MOUNTED JOHNSON, 142-0701-851 10 0 R1 RES., CHIP, 348Ω, 1%, 0402 YAGEO, RC0402FR-07348RL 11 0 R3, R4 RES., CHIP, 0Ω, 1/16W, 5%, 0603 OPT 12 4 R13, R14, R17, R18 RES., CHIP, 0Ω, 1/16W, 5%, 0603 YAGEO, RC0603JR-070RL 13 0 T1, T2 XFMR, MINI-CIRCUITS OPT 14 0 T3, T4 XFMR, 2:1 OPT 15 1 U1 IC, IF AMP., QFN24UF-4X4 LINEAR TECH., LTC6431AIUF-15 dc1774acfa 8 DEMO MANUAL DC1774A-C Figure 6. DC1774A RF/IF AMP/ADC Driver SCHEMATIC DIAGRAM dc1774acfa 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. 9 DEMO MANUAL DC1774A-C 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 © 2004, Linear Technology Corporation dc1774acfa 10 Linear Technology Corporation LT 0213 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013