User's Guide
SCAU039–October 2009
Low Additive Phase Noise Clock Buffer Evaluation Board
Figure 1. CDCLVP2104EVM Evaluation Board
Features:
• Easy-to-use evaluation board to fan out low phase noise clocks
• Easy device setup
• Fast configuration
• Control pins configurable through jumpers
• Board powered at +2.5-V/+3.3-V
• Single-ended or differential input clocks
• CDCLVP2104 supports eight LVPECL outputs; CDCLVP2104EVM supports four LVPECL outputs
Contents
1 General Description ......................................................................................................... 2
2 Signal Path and Control Circuitry ......................................................................................... 2
3 Getting Started .............................................................................................................. 2
4 Input Clock Selection ....................................................................................................... 2
5 Output Clock ................................................................................................................. 3
6 Schematics and Layout .................................................................................................... 3
List of Figures
1 CDCLVP2104EVM Evaluation Board .................................................................................... 1
2 CDCLVP2104EVM—Schematic .......................................................................................... 3
3 CDCLVP2104EVM—Schematic .......................................................................................... 4
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General Description
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1 General Description
The CDCLVP2104 is a high-performance, low additive phase noise clock buffer. It has two universal input
buffers that support either single-ended or differential clock inputs. Each input feeds a bank of four
LVPECL outputs. The device also features on-chip bias generators that can provide the LVPECL
common-mode voltage to the device inputs.
This evaluation module (EVM) is designed to demonstrate the electrical performance of the CDCLVP2104.
This fully assembled and factory-tested evaluation board allows complete validation of the CDCLVP2104
device functionalities. Throughout this document, the acronym EVM and the phrases evaluation module
and evaluation board are synonymous with the CDCLVP2104EVM. See Figure 1 for an illustration of the
CDCLVP2104EVM.
For optimum performance, the board is equipped with 50-ΩSMA connectors and well-controlled, 50-Ω
impedance microstrip transmission lines.
2 Signal Path and Control Circuitry
The CDCLVP2104 supports single-ended inputs up to 200 MHz and differential inputs up to 2 GHz. The
device provides up to eight LVPECL outputs operating at the input frequency. For more information about
the CDCLVP2104, see the CDCLVP2104 product data sheet available for download from the TI web site
(www.ti.com).
3 Getting Started
The CDCLVP2104EVM has self-explanatory labeling and uses similar naming conventions as the
CDCLVP2104 product data sheet. In this user's guide, all words in boldface and italic print reflect the
actual labeling on the EVM. The CDCLVP2104EVM can be used with either single-ended or differential
inputs.
3.1 Power-Supply Connections
Connect the power-supply source to the banana plug labeled VDD (P4), and connect the ground of the
power-supply source to GND (P5). There are decoupling capacitors and a ferrite bead to isolate the EVM
power from the CDCLVP2104 device power pins.
The CDCLVP2104EVM can use a supply voltage of 2.375 V to 3.6 V.
4 Input Clock Selection
The CDCLVP2104EVM offers users the option of receiving either a differential or single-ended clock as
the clock input. The default option is for the differential signal at both device inputs. The inputs can be
applied through the SMAs (J103, J104 or J105, J106). These inputs are ac-coupled to the device inputs.
The common-mode voltage for these inputs after the ac-coupling capacitors is provided by 50 Ω(R152,
R153 and R154, R155) to the device on-chip bias generator (VAC_REF) pins.
4.1 Configuring Single-Ended Input
For a single-ended clock applied to IN0, remove capacitors C68 and C69 and replace them with 0-Ω
resistors of the same footprint. The single-ended signal should be applied to INP0 (J103) and the dc bias
voltage should be applied to INN0 (J104).
For a single-ended clock applied to IN1, remove capacitors C72 and C73 and replace them with 0-Ω
resistors of the same footprint. The single-ended signal should be applied to INP1 (J105) and the dc bias
voltage should be applied to INN1 (J106).
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Output Clock
5 Output Clock
The CDCLVP2104 generates up to eight LVPECL outputs. Four outputs are available on the
CDCLVP2104EVM (outputs 0, 3, 4, and 7) through the following SMAs:
• J13, J23 for OUT0
• J17, J27 for OUT3
• J33, J32 for OUT4
• J39, J38 for OUT7
The LVPECL outputs are terminated with 150 Ωto ground and ac-coupled to the respective SMAs.
6 Schematics and Layout
Figure 2 and Figure 3 show the printed circuit board (PCB) schematics.
NOTE: Board layouts are not to scale. These figures are intended to show how the board is laid
out; they are not intended to be used for manufacturing CDCLVP2104EVM PCBs.
Figure 2. CDCLVP2104EVM—Schematic
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It is important to operate this EVM within the input voltage range of –0.5 V to 4.0 V and the output voltage range of 0 V to 3.6 V.
Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are
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specification, please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than +120° C. The EVM is designed to
operate properly with certain components above +85° C as long as the input and output ranges are maintained. These components
include but are not limited to linear regulators, switching transistors, pass transistors, and current sense resistors. These types of
devices can be identified using the EVM schematic located in the EVM User's Guide. When placing measurement probes near
these devices during operation, please be aware that these devices may be very warm to the touch.
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