DC1795A Analog Devices

DEMO MANUAL DC1795A LTC6950 1.4GHz Low Phase Noise, Low Jitter PLL with Clock Distribution Description Demonstration circuit 1795A features the LTC 6950, a For the evaluation of the LTC6950 with other VCOs and 1.4GHz low phase noise, low jitter PLL with clock dis- references, the DC1795A can be modified to accommodate tribution. different on-board or external components. It also allows the user the option of a passive or active loop filter. For ease of use, the DC1795A comes installed with a 100MHz reference and a 1GHz VCSO, voltage controlled A DC590 USB serial controller board is used for SPI com- SAW oscillator with sine wave output. All differential munication with the LTC6950, controlled by the supplied inputs and outputs have 0.5 spaced SMA connectors. ClockWizard software. The DC1795A has four AC coupled LVPECL outputs with Design files for this circuit board are available at 50 transmission lines making them suitable to drive DEMO MANUAL DC1795A Quick s p D The DC1795A is easy to set up to evaluate the performance Connect the DC590 to one of your computers USB ports of the LTC6950. Follow the procedure below. with the included USB cable. The DC590 and ClockWizard application are required to Clo CkWiz Ar D inst All Ation control the DC1795A through a personal computer (PC). The ClockWizard software is used to communicate with DC590 Con Figur Ation the LTC6950. It uses the DC590 to translate between USB and SPI-compatible serial communications formats. It also Place the DC590 jumpers in the following positions (refer includes advanced PLL design and simulation capabilities. to Figure 2): The following are the ClockWizard system requirements: JP4: EE - Must be in the EN position. Windows Operating System: Windows XP, Windows JP5: ISO - ON must be selected. 2003 Server, Windows Vista, Windows 7 JP5: SW - ON must be selected. Microsoft .NET 3.5 SP1 or later JP6: VCCIO - 3.3V or 5V must be selected. This sets Windows Installer 3.1 or later the SPI port to 3.3V or 5V operation. 3.3V operation is Linear Technologys DC590 hardware recommended. J4,ribbon J3,USB c a b l e conne ction conne ction toP C tothe DC1795 JP4 JP6 j u m p e r jumpers JP5jumpers Figure 2. DC590 Jumper and Connector l ocations dc1795af 2 ure roce tart