DEMO MANUAL DC1649A LTC6945 Ultralow Noise and Spurious Integer-N Synthesizer DESCRIPTION Demonstration circuit 590 is used for SPI communication Demonstration circuit 1649A features the LTC 6945, an with the LTC6945, controlled by the supplied PLLWizard ultralow noise and spurious integer-N synthesizer. software. DC1649A provides 50 SMA connectors for the reference Design files for this circuit board are available at frequency (REF+), the reference output buffer (REFO), DEMO MANUAL DC1649A TYPICAL DC1649A REQUIREMENTS AND CHARACTERISTICS PARAMETER INPUT OR OUTPUT PHYSICAL LOCATION DETAILS 3.3V Power Supply Input J9 and J10 Banana Jacks Low Noise and Spur-Free 3.3V, 95mA 5V Charge Pump Power Supply Input J11 and J12 Banana Jacks Low Noise and Spur-Free 5V, 35mA 5V VCO Power Supply Input V+VCO Turret Low Noise and Spur-Free 5V, 18mA REF+, Reference Frequency Input J2 SMA Connector Low Noise 10MHz or 100MHz*, 6dBm into 50, See Note 1 REFO, Buffered Reference Output J1 SMA Connector Frequency = f , 0dBm REF RF+ and RF Two Outputs J6 and J7 SMA Connectors 902MHz to 928MHz* in 250kHz* Steps, 0dBm Loop Bandwidth Set by Loop Filter Component Values 7kHz* *These frequencies are for the DC1649A-10MHz.pllset or DC1649A-100MHz.pllset files and included VCO. Note 1: A low noise 10MHz or 100MHz reference frequency, such as the Ref BST and FILT under the System tab in PLLWizard might need to be Wenzel 501-04608A or 501-04516D OCXO, is recommended. If using a changed if the reference frequency and/or power is different than what is different frequency, make sure to update the Fref and R DIV boxes under recommended in the table above. More information can be found in the the System tab in PLLWizard so that Fpfd is still 250kHz. For example, if a LTC6945 data sheet. 20MHz clock is used, Fref should be changed to 20MHz and R DIV to 80. QUICK START PROCEDURE The DC590 and PLLWizard application are required to 3. Run the QuikEval installation program and follow the control the DC1649A through a personal computer (PC). on-screen instructions. More detailed installation infor- mation may be found in the DC590s Quick Start guide. DC590B Configuration 4. Exit the QuikEval program once the installation is com- The DC590s QuikEval drivers must be installed before plete, as it is not needed to run the PLLWizard software. the DC590 will be able to communicate with the LTC6945. 5. Place the DC590 jumpers in the following positions: To configure the DC590, follow the procedure below, start- ing with Step 1. If you have already installed the DC590 JP4 - EE Must be in the EN position. software previously, skip to Step 5. JP5 - ISO ON must be selected. Note: Once the QuikEval software is installed, the applica- JP5 - SW ON must be selected. tion Does Not need to be executed to run PLLWizard or to JP6 - VCCIO 3.3V must be selected. This sets the SPI control the DC1649A. port to 3.3V operation. 1. Do Not plug in the DC590 before running the installation 6. Connect the DC590 to one of your computers USB program. ports with the included USB cable. 2. Download the QuikEval installation program from