DEM-FDA-DGK-EVM

www.ti.com Table of Contents User’s Guide DEM-FDA-DGK-EVM User's Guide ABSTRACT The DEM-FDA-DGK-EVM is an unpopulated evaluation module (EVM) for fully differential amplifiers (FDA) in the DGK (HVSSOP) package. This EVM is designed in accordance with high-speed performance specifications and Texas Instruments' FDAs with output common mode (Vocm) control and power down (PD) functionality. The EVM is designed to enable quick and efficient lab testing of TI High Speed FDAs using 50-Ω SMA connectors for use with lab equipment. All the necessary connectors to perform lab measurements, including power and signal connections, are considered for this schematic. The EVM is configured for single-ended input and singleended output when populated according to the schematic; the EVM can accommodate fully differential behavior with proper configuration. The output transformer enables single-ended output for easy interfacing with test equipment, and there are external SMA connectors for output common mode and power down control. Additional options on input traces prior to termination resistors and extensions of transformer pads allow for optional AC coupling. Table of Contents 1 Features...................................................................................................................................................................................2 2 EVM Specifications.................................................................................................................................................................2 2.1 Power Supply Connections................................................................................................................................................ 2 2.2 Input and Output Connections........................................................................................................................................... 2 2.3 Output Common Mode Control (Vocm)..............................................................................................................................2 2.4 Power Down Function........................................................................................................................................................ 2 3 Example Schematic and Layout Using THS4130.................................................................................................................3 List of Figures Figure 3-1. Schematic with Example Configuration Using the THS3140.................................................................................... 3 Figure 4-1. PCB Top Layers........................................................................................................................................................ 4 Figure 4-2. PCB Second Layer (Ground).................................................................................................................................... 4 Figure 4-3. PCB Third Layer (Power).......................................................................................................................................... 4 Figure 4-4. PCB Bottom Layers...................................................................................................................................................4 Trademarks All trademarks are the property of their respective owners. SLOU554 – OCTOBER 2021 Submit Document Feedback DEM-FDA-DGK-EVM User's Guide Copyright © 2021 Texas Instruments Incorporated 1 Features www.ti.com 1 Features • • • • • Split or single supply operation Configurable gain and feedback network with optional compensation capacitors Supports single-ended or differential inputs Designed for easy connection to standard 50-Ω input and output impedance lab equipment Inputs, outputs, and control signals all include SMA connectors for high speed operation 2 EVM Specifications Section 2.1 through Section 2.4 provides a general description of the DEM-FDA-DGK-EVM specifications and configurations. 2.1 Power Supply Connections While operating as split supply, apply positive supply voltage to VCC+, negative supply to VCC-, and ground reference from supply to GND. The board can also be configured for single supply operation by connecting the positive supply voltage to VCC+ and ground to GND and VCC-. 2.2 Input and Output Connections The DEM-FDA-DGK-EVM is equipped with SMA input and output connectors for simple interface to signal generators and analysis equipment. To obtain the best results, use of 50-Ω characteristic impedance cables is recommended between the EVM and lab equipment. The example schematic in Figure 3-1 shows the EVM configured for a single-ended input with a differential output that is also converted to a single-ended signal through the transformer (T1). This example configuration makes it easy to interface the board with single ended input and output test equipment. In this example case, the input impedance is balanced to accept a connection from a 50-Ω characteristic connection. The resistor R9 is set to 26.1-Ω to provide a balanced impedance that would match the parallel combination formed by the test equipment 50-Ω impedance and resistor R4. The board can also be configured for differential inputs and differential outputs. Differential inputs can be applied by populating both input SMA connectors (J3 and J5). When using differential inputs, it is important to balance the impedances created by resistors R4 and R9 so that each input is balanced to the same impedance. Otherwise an impedance imbalance will cause output errors. For differential outputs, a shorting resistor should be placed between terminals 1 and 6 and also between terminals 3 and 4 of the transformer (T1) footprint. Both output SMAs should be populated and resistors R11 and R15 removed. It may be necessary to adjust the output loading network formed by R8, R12, and R14 if a differential output impedance match other than 50-Ω is required. 2.3 Output Common Mode Control (Vocm) FDAs have a feature to externally drive output common mode (Vocm). This feature can be utilized by populating equivalent value resistors for R1 and R2 to VCC+ and VCC-. This sets the output common mode to mid-supply, a common configuration. Additionally, the option to drive Vocm with the SMA connector exists. For this use case, do not populate R1 or R2. If there is need to terminate the Vocm signal source into 50-Ω, C3 can be replaced by a 50-Ω resistor. 2.4 Power Down Function Many TI op-amps have a shutdown or power down (PD) feature; this allows for the amplifier to appear as a high impedance load and enables low current draw. This feature is often active low and can be left floating or be driven to a value. In the case of the THS4130 shown in the schematic, driving the PD pin to VCC- will place the amplifier in power down. For convenience and ease of use, the EVM contains a header and jumper to control PD functionality without externally driving the PD pin. If an external signal is needed to drive PD, removing the jumper will enable input through the SMA connector. For specific amplifier power-down polarity, please refer to the respective device data sheet. 2 DEM-FDA-DGK-EVM User's Guide SLOU554 – OCTOBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com Example Schematic and Layout Using THS4130 3 Example Schematic and Layout Using THS4130 Figure 3-1 shows the DEM-FDA-DGK-EVM schematic in an example configuration using the THS4130 fully differential amplifier. Figure 4-1 through Figure 4-4 show the PCB layer prints for the top traces, ground plane, power plane, and bottom traces respectively. VCC+ J1 VCC+ R1 10.2k Vocm J2 VCC+ GND C2 50V 0.1uF 1 2 3 4 5 C1 50V 10uF R2 10.2k GND C3 100nF 50V C4 220pF 50V GND GND VCC- GND R3 J3 VIN- 390 R4 56.0 1 VCC+ J4 VOUT- GND J5 VIN+ R7 1 C6 50V 100pF 4 8 5 7 2 3 4 5 383 R8 0 C5 50V 220pF R13 0 388 R12 53.6 R14 4 T1 3 5 2 6 388 1 TT1-6-KK81+ GND R10 390 GND GND J6 VOUT+ 1 R15 49.9 VCC- R9 26.1 R11 49.9 5 4 3 2 3 1 R5 5 4 3 2 383 U1 THS4130IDGK 6 2 3 4 5 1 2 R6 GND GND C7 GND 220pF 50V J7 TP1 TP2 TP3 TP4 5011 5011 5011 5011 VCC+ J9 VCC- J10 1 SH-J1 J8 1 C8 50V 10uF C9 50V 0.1uF GND TMM-103-01-T-S 2SN-BK-G GND GND GND GND GND VCCGND GND GND 2 3 PD 2 3 4 5 VCC- C10 50V 0.1uF GND Figure 3-1. Schematic with Example Configuration Using the THS3140 SLOU554 – OCTOBER 2021 Submit Document Feedback DEM-FDA-DGK-EVM User's Guide Copyright © 2021 Texas Instruments Incorporated 3 www.ti.com 4 Figure 4-1. PCB Top Layers Figure 4-2. PCB Second Layer (Ground) Figure 4-3. PCB Third Layer (Power) Figure 4-4. PCB Bottom Layers DEM-FDA-DGK-EVM User's Guide SLOU554 – OCTOBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated IMPORTANT NOTICE AND DISCLAIMER TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS. These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, regulatory or other requirements. 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