• 16-Bit Wide ECL 100K Compatible Parallel Data
Interface
• Differential High-Speed Data Outputs
• Differential or Single-Ended High-Speed Data and
Clock Inputs
• On-Chip Phase Detector (VSC8061 Multiplexer)
• Power Dissipation: VSC8061:2.0W(max),
VSC8062: 1.7W(max)
• Standard ECL Power Supplies: V
V
= -2.0V
TT
• Commercial (0oC to +70oC) or Industrial (-40oC
to +85o C) Temperature Range
• Available in 52-Pin Ceramic Leaded Chip Carrier
or 52-Pin Plastic Quad Flat Pack Packages
= -5.2V,
EE
Functional Description
The VSC8061 and VSC8062 are high-speed interface devices capable of data rates up to 2.5Gb/s. The
devices are fabricated in gallium arsenide using the Vitesse H-GaAs E/D MESFET process to achieve highspeed and low power dissipation. For ease of system design using these products, both devices use industrystandard -5.2V and -2V power supplies, and have ECL-compatible I/O for parallel data interfaces. Typical
applications include telecommunication transmission and instrumentation.
VSC8061 Multiplexer
The VSC8061 consists of a 16:1 multiplexer circuit, a phase detector, and a timing circuit which generates
a divide-by-16 clock from the high-speed clock input. The 16:1 multiplexer accepts 16 parallel single-ended
ECL compatible inputs (D0...D15) at data rates up to 156Mb/s and bitwise serializes them into a 2.5Gb/s serial
output (DO/DON). The internal timing of the VSC8061 is referenced to the negative going edge of the highspeed clock true input (CLK). This clock is divided by 16 and is provided as an output (CLK16/CLK16N). The
setup and hold time of the parallel inputs (D[0:15]) are specified with respect to the falling edge of CLK16, so
that CLK16/CLK16N can be used to clock the data source of D[0:15]. The on-chip phase detector monitors the
phase relationship between the internally generated divide-by-16 clock and an externally supplied low-speed
reference clock input (DCLK/DCLKN). Phase difference between these two clock signals generates an up or
down output (U, D) for phase lock applications. The phase detector can be used as part of an external Phase
Locked Loop (PLL) to implement a clock multiplication function.
In applications where a 2.5GHz system clock is provided, and the phase detector function is not required, it
is recommended to connect one side of the DCLK/DCLKN input to VTT through a 50Ω resistor. The U and D
output can be left open and unused.
VSC8062 Demultiplexer
The VSC8062 consists of a 1:16 demultiplexer and timing circuitry which generates a divide-by-16 clock
from the high-speed clock input. The demultiplexer accepts a serial data stream input (DI/DIN) at up to 2.5Gb/s
and deserializes it into 16 parallel single-ended ECL compatible outputs (D[0:15]) at data rates up to 156 Mb/s.
The internal timing of the VSC8062 is referenced to the negative going edge of the high-speed clock true input
(CLK). This clock is divided by 16 and provided as an output (CLK16/ CLK16N). The timing parameters of the
parallel data outputs (D[0:15]) are specified with respect to the falling edge of CLK16, so that CLK16/CLK16N
can be used to clock the destination of D[0:15].
VSC8061 Multiplexer AC Characteristics (Over recommended operating range)
Figure 3: VSC8061 Multiplexer Waveforms
t
CLK
2.5Gb/s 16-Bit
High-speed differential clock input
CLK (CLKN)
t
D
CLK16 (CLK16N)
Parallel data clock output
D[0:15]
Parallel data inputs
t
DSU
VALID DATA (1)
t
DH
VALID DATA (2)
DCLK (DCLKN)
Parallel data clock input
DO (DON)
High-speed differential serial data output
NOTE:
Table 1: VSC8061 AC Characteristics
ParameterDescriptionMinTypMaxUnitsConditions
t
CLK
t
D
t
DSU
t
DH
t
DC
tR, t
F
tR, t
F
tR, t
F
tR, t
F
NOTE: (1) Devices are guaranteed to operate to a maximum frequency of 2.5GHz.
Clock period
CLK16, DCLK period (t
Parallel data set-up time with respect to CLK16
falling edge
Data hold time with respect to CLK16 falling
edge
CLK16 duty cycle4060%
DCLK (DCLKN) rise and fall times1.5ns10% to 90%
D[0:15] rise and fall times2.0ns10% to 90%
CLK16 (CLK16N) rise and fall times0.51.0ns10% to 90%
DO (DON) rise and fall times150165ps20% to 80%
The internal phase detector of the VSC8061 compares the phase difference between the internally generated divide-by-16 clock and the DCLK input. If both inputs (CLK16 and DCLK) to the phase detector are in
phase, the U and D outputs will both be low. If the rising edge of CLK16 precedes DCLK, a series of pulses
with pulse widths proportional to the phase difference will be present at the U output. Conversely, if DCLK precedes CLK16, then a series of pulses with widths proportional to the phase difference will be present at the D
output. The other output will remain low. The Phase Detector ignores phase differences for falling edges. This
circuitry is useful for implementing a Clock Multiplier Unit (CMU) function with the VSC8061. For example,
the DLCK can be the system reference clock at the parallel data rate. An external Voltage Controlled Oscillator
(VCO) at 16x the frequency of the reference clock can be used as the CLK input for the VSC8061. The phase
detector outputs (U and D) can then be used by an external integrator to generate an output that controls the
VCO. The generated 16x clock from the VCO will be phase-locked to the reference clock.
Figure 4: VSC8061 Phase Detector Logic Diagram
CLK16
RSQ
U
CLK16
DCLK
S
R Q
DCLK
Figure 5: Phase Detector Input and Output Waveforms