DEMO CIRCUIT DC1147 QUICK START GUIDE DEMO CIRCUIT 1147 LOW NOISE/DISTORTION 16-BIT DIFFERENTIAL ADC DRIVERS QUICK START GUIDE LTC6404-x, LTC6406,LTC6405 and LTC6403-1 16-Bit Differential ADC Drivers DESCRIPTION Demonstration circuit 1147 features the LTC6404-x, These fully-differential amplifiers accept single-ended or LTC6406, LTC6403-1, and LTC6405 16-bit ADC Drivers. It differential inputs with almost no difference in distortion incorporates a variety of passive components to support performance. Each part has the ability to independently ad- configurations for varied applications. Single-ended or dif- just the output common-mode voltage without any addi- ferential input and output configurations are possible, and tional components, and flexible input common-mode there is a calibration circuit to null out the effects of other ranges which enable level-shifting of input signals for ADC circuit components. driving applications. Design files for this circuit board are available. Call The LTC640x are high-speed differential amplifiers with su- the LTC factory. perior distortion and noise performance, perfect for de- , LTC and LT are registered trademarks of Linear Technology Corporation. manding communications transceivers, cellular base- stations, and other high-speed signal chain applications. QUICK START PROCEDURE Table 1: DC1147 Board I/O Descriptions Table 1 shows the function of each SMA connector on the CONNECTOR FUNCTION board. Refer to Figure 1 for the connection diagram and J1 (IN+) Differential Input. Use this connector to supply an input follow the procedure below: to the DC1147. Drive from a 50ohm signal source, no 1. Connect the power supply as shown. The power labels of external termination necessary. V+, VOCM, and GND directly correspond to the power J2 (OUT-) Differential Output. Not connected by default. Resistor supply and VOCM pins of the LTC640x ICs (U1). Jumper R9 can installed and R10 removed to receive the output signal differentially. JP1 enables or shuts down the amplifier. J3 (OUT+) Output. Impedance-matched to 50 ohms, can be used 2. The power supplies available for each part are shown in to drive a 50ohm network/spectrum analyzer input. Table 1. Do not exceed the maximum power supply J4 (IN-) Differential Input. Not connected by default. Resistor voltage for the parts. R24 can be installed and R27 removed for differential input drive. R4 and R7 should be matched or both re- 3. Apply an input signal to J1. A low-distortion, low moved to provide a balanced input impedance. noise signal source with an external high-order filter JP1 (SHDN) Shutdown jumper. The left (EN) position enables the part, while the right (DIS) puts it into shutdown mode. will yield the best performance. DC1147s input is E3 (VOCM) Output Common-Mode Adjust. By default, this pin is impedance-matched to 50 no external termination self-biasing within U1. Override this voltage with any is necessary. DC voltage source. E5 (VTIP) Corresponds to the VTIP pin in DC1147-D 4. Observe the output via J3. The output is impedance- (LTC6405/6). Consult the datasheet for pin function. matched to 50, suitable for the input of a network or Leave floating if unused. This pin is not connected for spectrum analyzer. all the other parts in the family. 1 DEMO CIRCUIT DC1147 QUICK START GUIDE LOW NOISE/DISTORTION 16-BIT DIFFERENTIAL ADC DRIVERS Figure 1: Proper Measurement Equipment Setup ADDITIONAL INFORMATION DC1147A-C LTC6404-4 2.7-5.25V Although the DC1147 demo board is ready to use out of DC1147A-D LTC6406 2.7-3.5V the box, it has features that you can access by adding, re- DC1147A-E LTC6403-1 2.7-5.25V moving or changing components on the board. These are DC1147A-F LTC6405 2.7-5.25V described below. DIFFERENTIAL INPUTS DEMO BOARD VERSIONS To drive the inputs differentially, remove resistor R27 and DC1147 has four versions to support all of the pin- install R24. J1 and J4 can now be driven differentially from compatible parts in the LTC640x amplifier family. Table 1 a 50 signal source. R4 and R7 should be changed to dif- contains a listing of the different amplifiers and their supply ferentially match the input to 50 if necessary. voltage ranges. See the schematic (on the last page of this guide) for component differences between the versions. DRIVING THE INPUTS DC-COUPLED DEMO BOARD SUPPLY VOLTAGES It is possible to drive the DC1147 inputs differentially with DC coupling. Transformer T1 should be replaced with 0 Table 2: DC1147 Supply Voltages resistors. The inputs are now DC-coupled and can be dri- DEMO U1 SUPPLY VOLTAGE RANGE BOARD ven single-ended or differentially (resistor values may be DC1147A-A LTC6404-1 2.7-5.25V changed to balance the source impedances, et cetera. See DC1147A-B LTC6404-2 2.7-5.25V 2