DEMO MANUAL DC1705C LTC6946 Ultralow Noise and Spurious Integer-N Frequency Synthesizer with Integrated VCO DESCRIPTION DC1705C features the LTC 6946, an ultralow noise and output buffer (REF OUT), and the differential RF output + spurious integer-N frequency synthesizer with integrated (RF and RF ). A DC590 USB serial controller board is VCO. The VCO uses no external components and is inter- used for SPI communication with the LTC6946, controlled nally calibrated without external system support. by the supplied PLLWizard software. There are four options of the DC1705C, one for each ver- Design files for this circuit board are available at sion of the LTC6946. Table 1 summarizes the available DEMO MANUAL DC1705C TYPICAL DC1705C REQUIREMENTS AND CHARACTERISTICS PARAMETER INPUT OR OUTPUT PHYSICAL LOCATION DETAILS 3.3V Power Supply Input 3.3V and GND Banana Jacks Low Noise and Spur-Free 3.3V, 115mA 5V Power Supply Input 5V and GND Banana Jacks Low Noise and Spur-Free 5V, 45mA + REF IN, Reference Frequency Input J1 SMA Connector Low Noise 10MHz or 100MHz*, 6dBm into 50 (Note 1) REF OUT, Buffered Reference Output J3 SMA Connector Frequency = f , 0dBm REF + RF and RF Two Outputs J4 and J5 SMA Connectors Frequency: 900MHz*, Power: 0dBm, Frequency Range: Depends on the version of the LTC6946 device refer to Table 1, Step Size: 200kHz* Loop Bandwidth Set by Loop Filter Component Values 47kHz* * These frequencies are for the DC1705C pllset files included with PLLWizard. Note 1: A low noise 10MHz or 100MHz reference frequency, such as the Wenzel 501-04608A or 501-04516D OCXO, is recommended. If using a different frequency, make sure to update the f and R DIV boxes under the System tab in PLLWizard so that f is still 1MHz. For example, if a 20MHz clock is REF PFD used, f should be changed to 20MHz and R DIV to 20. REF BST and FILT under the System tab in PLLWizard might need to be changed if the reference REF frequency and/or power is different than what is recommended in the table above. More information can be found in the LTC6946 data sheet. Table 1. DC1705C Options and Frequency Ranges ASSEMBLY VERSION PART NUMBER VCO FREQUENCY RANGE (GHz) OUTPUT DIVIDER SETTINGS DC1705C-A LTC6946IUFD-1 2.240 to 3.740 Integers 1 through 6 DC1705C-B LTC6946IUFD-2 3.080 to 4.910 Integers 1 through 6 DC1705C-C LTC6946IUFD-3 3.840 to 5.790 Integers 1 through 6 DC1705C-D LTC6946IUFD-4 4.200 to 6.390 Integers 1 through 6 dc1705cfb 2