DC1241B-AD Analog Devices

DEMO CIRCUIT 1241 DC1241 QUICK START GUIDE LTM9001 16-Bit IF/Baseband Receiver Subsystem DESCRIPTION Demonstration circuit 1241 is an evaluation board featur- ing CMOS outputs for evaluation of the part with ing Linear Technology Corporations LTM9001 16-bit CMOS outputs, obtain DC1250. DC1241 plugs into the Receiver Subsystem. DC1241 demonstrates good circuit DC890 Data Acquisition demo board and the output can layout techniques and recommended external circuitry be easily analyzed with Linear Technologys PScope data for optimal system performance. processing software, which is available for no charge on our website at DC1241 DC890 will also require an external +6V/1A power supply when receiving LVDS outputs. Power Supply (3.8V-6V 1.0A) NOTE. Even a high-quality signal synthesizer will still have noise and harmonics that should be attenuated with a low-pass or band-pass filter. For good-quality high order filters, see TTE, Lark Engineering, or equivalent. Signal To DC890 Generator BPF HP 8644B or equiv. RF Signal Generator (HP 8644B) or other low phase noise BPF clock source (e.g. DC1216) Figure 1. Proper Evaluation Equipment Setup ADDITIONAL INFORMATION Although the DC1241 demo board is ready to use on de- el-shifted to within the input common-mode limits in the livery, it has additional flexibility built in for various types datasheet. of input networks. Below is some information about con- Table 2: DC1241 Input Configuration Guide figuring DC1241 to meet the specific needs of your eval- CONFIGURATION COMPONENTS NECESSARY uation. Single-Ended Input No change. Transformer T1 acts as a balun for differential drive. AC-Coupled APPLYING INPUT SIGNALS (Default Setup) Single-Ended Input Remove T1, replace with 0 jumpers. May need The input network consists of various components de- to install impedance-matching resistor at No Transformer signed to allow either single-ended or differential inputs, R30 or R4/R5. AC-Coupled AC-coupled or DC-coupled. Table 2 shows some possi- Single-Ended Input Same as above. Change C1 and C3 to 0 jump- ble input configurations, and which components to in- ers. Inputs must be within the common- No Transformer mode voltage limits of LTM9001. stall. LTM9001 is designed for excellent performance DC-Coupled with both single-ended and differential input drive, with Differential Inputs Remove R27 and install R26. T1 and C1/C3 can be replaced with 0 for DC coupling. little difference in distortion performance. When using DC-coupled inputs, the inputs to DC1241 need to be lev- 2