DC1660B - LINEAR TECHNOLOGY

dc1660bf

DEMO MANUAL DC1660B

Description

LTC6417

1.6GHz Low Noise Differential

16-Bit ADC Buffer

Demonstration circuit 1660B features the LTC

6417 dif-

ferential 16-bit ADC buffer. The demo board incorporates a

variety of passive components to allow for direct connec-

tion to a two-port network analyzer or other single-ended

50Ω test system.

The demo board is easily configured to control common-

mode voltage VCM, clamp voltage CLHI, power adjust

PWRADJ, and SHUTDOWN pins. Other simple PCB modifi-

cations can accommodate differential input/output signals.

Design files for this circuit board are available at

http://www.linear.com/demo

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Quick start proceDure

DC1660B is easy to set up to evaluate the performance of

the LTC6417. Refer to Figure 1 for proper measurement

equipment setup and follow the procedure below:

1. Connect SMA cables to IN+ and OUT+ ports.

2. Apply 5.0V between V+ and GND turrets.

Tie PWRADJ (TURRET E4) to V+. Limit supply current

to approximately 150mA.

3. VCM, CLHI and SHDN turrets may be left floating.

This procedure contains a critical sequence. The user

must apply supply voltage before applying signal power

to the inputs or forcing a voltage to any other turrets. The

user must also remove the signal from the input ports

and voltages on any other turret before turning down

the supply voltage. This proper sequence will prevent

excessive current through the ESD diodes from any pin

to the positive supply V+. Table 1 shows the function of

each SMA connector on the board. Only J1, J3 and J5

are used in the default configuration. J2 and J4 provide

flexibility for differential input/output signals.

Table 1. DC1660B SMA Connectors

CONNECTOR FUNCTION

J1 (IN+) Differential input connected to input balun for single-

ended operation. Drive from a 50Ω signal source.

No external termination needed.

J2 (IN–) Differential Input. Not connected by default. Remove

capacitor C12 to drive the input balun differentially.

J3 (OUT+) Differential output connected to balun for single-ended

operation. Connect to a 50Ω network/spectrum

analyzer input.

J4 (OUT–) Differential Output. Not connected by default. Remove

capacitor C11 to drive the input balun differentially.

J5 (OR) Overrange Output. Connect to oscilloscope for

monitoring the output signal.

dc1660bf

DEMO MANUAL DC1660B

Figure 1. Proper Measurement Equipment Setup

Quick start proceDure

DC1660B F01

Signal

Generator

Spectrum

Analyzer

DC Power Supply

GND V+

V+ = 4.75V to 5.25V

IMPEDANCE

RATIO

R2 = R6 =

VALUE (Ω)

POWER

GAIN (dB)

MABA-007159-000000 1:1 24.9 0

TMC4-19+ 1:4 100

1:8 200

TC8-1G2+ 4.5

dc1660bf

DEMO MANUAL DC1660B

applications information

Input

Demo board DC1660B’s single-ended input is AC-coupled

at port J1. The balun transformer T1 has a 1:4 impedance

ratio and it is matched to 50Ω at its input, when resistors

R2 and R6 are equal to 100Ω.

To drive the inputs differentially, remove capacitor C12.

To DC-couple the inputs, replace DC blocking capacitors

C7 and C10 with 0Ω resistors.

Output

The board’s output transformer T2 has a 1:1 impedance

ratio. T2 converts the LTC6417’s differential output signals

to a single-ended output.

To match T2 to 50Ω, change output series resistors R1

and R3 to 23.7Ω each.

For differential outputs, remove capacitor C11.

To DC-couple the outputs, replace DC blocking capacitors

C5 and C9 with a 0Ω resistor.

Additional Information

The demo board DC1660B is ready to use out of the box.

The demo board is shipped with the default configuration

as single ended input and output. However, it has features

that you can access by adding, removing or changing

components on the board. Refer to LTC6417 data sheet

for more information.

Output Common Mode Adjustment

Turret E1, labeled VCM, controls the output common mode

voltage of the LTC6417.

This function can be used to set the DC output voltage for

optimum system performance.

In the default configuration, C5 and C9 block the DC out-

put voltages. Replace these capacitors with 0Ω jumpers,

and the transmission-line type transformer T2 will couple

the DC voltages to the output port J3. If turret E1 is left

floating, the LTC6417 will self-bias the VCM pin to 1.25V

on a 5.0V supply. The VCM pin has a voltage range from

0.85V to 1.65V.

CLHI

Turret E5, labeled CLHI, controls the high side clamping

voltage of the LTC6417. If turret E5 is left floating, the

LTC6417 will self-bias the CLHI pin to 2.5V on a 5.0V

supply. The internal low side clamping voltage and CLHI

is symmetric with respect to VCM. When CLHI = 2.5V, and

VCM = 1.25V, internal low side clamp will be 0V. Either

output will be limited by these clamp voltages. See the

LTC6417 data sheet for more information.

PWRADJ

Turret E4, labeled PWRADJ, scales the supply current of

the LTC6417. If turret E4 is left floating, the LTC6417 will

self-bias the PWRADJ pin to 1.6V on a 5.0V supply with

a supply current of approximately 115mA.

Shutdown

Turret E7, labeled SHUTDOWN, puts the LTC6417 into

sleep mode when pulled high, significantly reducing

supply current (~25mA). If turret E7 is left floating, the

LTC6417 will pull the SHUTDOWN pin to GND potential

and remain enabled.

Schematic Note

The schematic included at the end of this Quick Start Guide

includes approximate power gains at various points along

DC1660B’s signal chain. The power gains (PG1 – PG4)

assume single-ended 50Ω test system and the LTC6417

is operating in a small-signal region. If the output load is

a high-impedance load, the power gains PG3 – PG4 will

vary from the schematic.

dc1660bf

DEMO MANUAL DC1660B

parts list

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

1 15 C1, C3, C4, C5, C7, C9, C10,

C13-C15, C17, C19-C21, C24

CAP., X5R, 0.1µF, 16V, 10% 0402 AVX, 0402YD104KAT2A

2 4 C2, C16, C18, C22 CAP., X7R, 680pF, 50V, 10% 0402 AVX, 04025C681KAT2A

3 2 C11, C12 CAP., X7R, 0.1µF, 25V, 20% 0603 AVX, 06033C104MAT2A

4 0 C6, C8, C23 CAP., OPT 0603 (OPT)

5 6 E1, E2, E3, E4, E5, E7 TESTPOINT TURRET, .061" PBF MILL-MAX, 2308-2-00-80-00-00-07-0

6 5 J1, J2, J3, J4, J5 CON., SMA 50Ω EDGE-LAUNCH E.F. JOHNSON, 142-0701-851/132357

7 2 R2, R6 RES., CHIP, 100Ω, 1/16W, 1% 0402 VISHAY CRCW0402100RFKED

8 4 R1, R3, R4, R5 RES., CHIP, 0Ω, 1/16W, 1% 0402 VISHAY, CRCW04020000Z0ED

9 0 R7, R8 RES., CHIP OPT 0402 (OPT)

10 1 T1 TRANSFORMER, TCM4-19+ SM-22 MINI-CIRCUITS TCM4-19+

11 1 T2 TRANSFORMER, ETC1-1-13, SM-22 M/A-COM, MABA-007159-000000 (PBF)

12 1 U1 I.C. LTC6417CUDC UDC 20 PIN (3×4) LINEAR, LTC6417CUDC#PBF

13 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 1660B

14 2 STENCILS TOP AND BOTTOM STENCIL DC1660B

dc1660bf

DEMO MANUAL DC1660B

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

schematic Diagram

C C

B B

A A

NOTE: UNLESS OTHERWISE SPECIFIED

1. ALL RESISTORS AND CAPACITORS ARE 0402

DEMO CIRCUIT 1660B

IN-

GND

V+

4.75V - 5.25V

PWRADJ

CL HI

SHUT

DOWN VCM

IN+

OUT+

OUT-

INPUT NETWORK POWER GAIN = PG1 BUFFER POWER GAIN = PG2

OUTPUT TERMINATION POWER GAIN = PG3 OUTPUT TRANSFORMER POWER GAIN = PG4

PG=Power Gain (dB)

DEMO BOARD SIGNAL CHAIN:

TRANSFORMATION

GPOITAR

Overall

100

24.9

23.7

R1=R3R2=R6

PG1

PG2

PG3

-3

PG4

0 0

-3

1:1

1:4

1:4TCM4-19+

MABA-007159-000000

TCM4-19+

-3

023.7

200TC8-1G2+

5.15.4200

1:8

4.5 0

4.51:8

TC8-1G2+

JOHN C.2ND PROTOTYPE 21-92-22

REVISION HISTORY

ETADNOITPIRCSED APPROVEDECO REV

Wednesday, February 29, 2012

1 1

ADC BUFFER

JOHN C.

N/A

LTC6417CUDC

SIZE

DATE:

.VER.ON CI

SHEET OF

TITLE:

APPROVALS

PCB DES.

APP ENG.

TECHNOLOGY

Fax: (408)434-0507

Milpitas, CA 95035

Phone: (408)432-1900

1630 McCarthy Blvd.

LTC Confidential-For Customer Use Only

CUSTOMER NOTICE

LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A

CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;

HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO

VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL

APPLICATION. COMPONENT SUBSTITUTION AND PRINTED

CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT

PERFORMANCE OR RELIABILITY. CONTACT LINEAR

TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.

THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND

SCHEMATIC

SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.

SCALE = NONE

www.linear.com

V+

V+ V+

C22

680pF

C24

0.1uF

OPT

0603

0.1uF

C14

0.1uF

TCM4-19+

0.1uF

OPT

C13

0.1uF

C11

0.1uF

0603

C10

0.1uF

C18

680pF

100

C15

0.1uF

OPT

0603

C12

0.1uF

0603

OPT

0.1uF

C19

0.1uF

C17

0.1uF

C16

680pF

C20

0.1uF

680pF

LTC6417CUDC

10 17

V+

GND

IN+

IN-

GND GND

OUT-

OUT+

GND

V+

PWRADJ

GND

CL HI

V+

SHUTDOWN

VCM

V+

GND

100

MABA-007159-000000

C23

OPT

0603

C21

0.1uF

dc1660bf

DEMO MANUAL DC1660B

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

 LINEAR TECHNOLOGY CORPORATION 2012

LT 0412 • PRINTED IN USA

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:

This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT

OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete

in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety

measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union

directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.

If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date

of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU

OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS

FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR

ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

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arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all

appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or

agency certified (FCC, UL, CE, etc.).

No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,

customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

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Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and

observe good laboratory practice standards. Common sense is encouraged.

This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC applica-

tion engineer.

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