VS8004

The VS8004 has the following features including Serial Data Rates up to 2.5 Gb/s;Parallcl Data Ratcs up to 625 Mb/s;ECL 100K Compatible Parallel Data I/Os;Dividc-by-4 Clock for Synchronization of Parallel Data to Interfacing Chips;SKIP Input on Demux for Realignment of Output Word Boundaries.

The VS8004 is a high speed 4 bit parallel to serial data converter suitable for digital voice or data communications applications. All inputs and outputs can be used differentially or single-ended. The parallel inputs [D(0:3), ND(0:3)] accept data at rates up to 625 Mb/s. The differential serial data output (SDATA, NSDATA) presents the data sequentially from the parallel data inputs al rates up Lo 2.5 Gb/s,synchronous with the differential high speed clock input (CLK, NCLK). An internal timing generator receives the high speed clock input and divides it by four to create a differential clock output (CLK4, NCLK4). This clock signal is provided so that incoming parallel signals can be syncluonized to arrive at the input data registers simultaneously. An internal bias network is provided at all inputs to simplify capacitive coupling.The VS8004 and VS8005 are data conversion devices capable of serial data rates up to 2.5 Gb/s, transforming 4-bit wide parallel data to serial data and serial data to 4-bit wide parallel data.The VS8004/VS8005 are fabricated in gallium arsenide using the Vitesse H-GaAsTNt E/D MESFET process which achieves high speed and low power dissipation. These products are packaged in a ceramic 28-pin leaded chip carrier.

The figure below is a schematic representation of these circuit boards. These boards provide a controlled impedance transmission line for all signals, and suitable decoupling for the power supplies. The signal traces have a characteristic impedance of SOS2,. All ECL input lines are terminated with SOS2, (chip resistor) as close to the device package pin as possible. The high speed inputs are also provided with 150 pF blocking capacitors.Signals are launched onto the circuit board and removed by means of SMA coaxial connectors. While the inputsignals are terminated, the output signals are provided open circuit and are intended to be terminated in the measuring instrument.