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19-1250; Rev 0; 6/97

MAX1002/MAX1003 Evaluation Kits

_______________General Description

The MAX1002/MAX1003 evaluation kits (EV kits) simplify

evaluation of the 60Msps MAX1002 and 90Msps

MAX1003 dual, 6-bit analog-to-digital converters (ADCs).

The kits include the basic components necessary to

operate the on-chip oscillator as a voltage-controlled

oscillator (VCO). Each board can also be easily modified

to accommodate an external clocking source.

Connectors for power supplies, analog inputs, and digital

outputs simplify connections to the device. The PC board

features an optimized layout to ensure the best possible

dynamic performance. The EV kits include a MAX1002 or

MAX1003.

____________________________Features

5.85 Effective Number of Bits at 20MHz Analog

Input Frequency

Separate Analog and Digital Power and Ground

Connections with Optimized PC Board Layout

Matched Single-Ended or Differential Analog

Inputs for Both I and Q Channels

Square-Pin Header for Easy Connection of Logic

Analyzer to Digital Outputs

User-Selectable ADC Full-Scale Gain Ranges

Fully Assembled and Tested

Evaluate: MAX1002/MAX1003

____________________Component List

DESIGNATION QTY

C1, C10,

C11, C12

C2, C3,

C6, C7

C4, C15

DESCRIPTION

0.01µF, 25V min, 10% ceramic

capacitors

47pF, 25V min, 5% ceramic capacitors

0.22µF, 25V min, 10% ceramic

capacitors

5pF, 10V min, 10% ceramic capacitor

(MAX1003)

22pF, 10V min, 10% ceramic capacitor

(MAX1002)

0.1µF, 10V min, 10% ceramic

capacitors

10µF, 10V min, 20% tantalum caps

AVX TAJC106K016

10kΩ, 5% resistor

47kΩ, 5% resistors

49.9Ω, 1% resistors

220nH inductor

Coilcraft 1008CS-221TKBC

MAX1003CAX, 90Msps

MAX1002CAX, 60Msps

Varactor diode

M/A-COM MA4ST079CK-287, SOT23

BNC connectors

MAX1002/MAX1003 circuit board

0Ω resistors

2-pin headers

3-pin header

2-pin header (MAX1002 only)

26-pin connector

Shunt for JU5

______________Ordering Information

PART

MAX1002EVKIT-SO

MAX1003EVKIT-SO

TEMP. RANGE

0°C to +70°C

BOARD TYPE

Surface Mount

______________Component Suppliers

SUPPLIER*

AVX

Coilcraft

M/A-COM

Sprague

PHONE

(803) 946-0690

(847) 639-6400

(617) 564-3100

(603) 224-1961

FAX

(803) 626-3123

(847) 639-1469

(617) 564-3050

(603) 224-1430

C8, C9,

C13, C14

C16, C17

R2, R3

R4–R7

IIN+, IIN-,

QIN+, QIN-

None

JU1, JU2,

JU6, JU7

JU3, JU4,

JU8, JU9

JU5

JU11

None

Please indicate that you are using the MAX1002/MAX1003

when contacting these component suppliers.

_________________________Quick Start

The MAX1002/MAX1003 EV kits are fully assembled

and tested. Follow these steps to verify proper board

operation.

Do not turn on the power supplies until all

connections to the EV kit are completed.

1) Connect a +5V power supply to the pad marked

VCC. Connect this supply’s ground to the pad

marked GND.

2) Connect a +3.3V (MAX1003) or +5V (MAX1002)

power supply to the pad labeled VCCO. Connect

the supply ground to the pad marked OGND.

3) Connect a +4V power supply to the pad marked

VTUNE. Connect the supply ground to the GND

pad.

4) Remove the shunt from jumper JU5. This sets a

250mVp-p full-scale range.

________________________________________________________________

Maxim Integrated Products

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

MAX1002/MAX1003 Evaluation Kits

Evaluate: MAX1002/MAX1003

5) Using an RF power splitter-combiner, connect a

250mVp-p, 20MHz sine-wave source to both analog

inputs at BNC J3 and J6. The analog input imped-

ance is 50Ω for each channel.

6) Connect a logic analyzer to connector J1 to monitor

the digital outputs.

7) Turn on all power supplies and signal sources.

8) Observe the digitized analog input signals with the

logic analyzer.

_______________Detailed Description

EV Kit Jumpers

The MAX1002/MAX1003 EV kits contain several

jumpers that control board and part options. The follow-

ing sections describe the different jumpers and their

purposes. Table 1 lists the jumpers on the EV kits and

their default positions.

MAX1002 Digital Outputs Supply

The MAX1002 uses +5V for its V

CCO

supply. As with

the MAX1003, the current requirement is a function of

the analog input frequency and capacitive loading on

the outputs. With 15pF loads and a 20MHz analog input

sampling at 60Msps, the current requirement is about

13mA. You can also use a single power supply for both

the V

and V

CCO

supplies by installing jumper JU11,

located near the EV kit power-supply connectors.

However, for best dynamic performance, use separate

analog and digital power supplies.

Analog Inputs

The analog inputs to the dual ADCs are provided

through BNC connectors IIN+, IIN-, QIN+, and QIN-.

The connectors are terminated with 49.9Ω to ground

and are AC coupled to the converter’s analog inputs,

which are internally self-biased at 2.35V DC. A typical

application circuit drives the IIN+ and QIN+ noninvert-

ing analog inputs using AC-coupled in-phase and quad-

rature signals. The nominal 20kΩ input resistance of the

analog inputs, plus the 0.1µF AC-coupling capacitor

value, sets the low-frequency corner at about 80Hz.

You can drive the analog inputs either single-ended or

differentially using AC- or DC-coupled inputs. Either the

inverting or the noninverting input can be driven single-

ended. If the inverting input is driven, then the digital

output codes are inverted (complemented). Refer to the

MAX1002 or MAX1003 data sheet for typical circuits.

Table 1. EV Kit Jumpers and Default

Positions

JUMPER(S)

JU1, JU2,

JU6, JU7

JU3, JU4,

JU8, JU9

JU5

FUNCTION

Power-supply current-

sense ports

Offset-correction

amplifier enabled

ADC full-scale range

selection

VCCO tied to VCC for

single-supply operation

(MAX1002)

DEFAULT

POSITION

Shorted with 0Ω

resistors

Open

ADC Gain Selection

The single GAIN-select pin on the MAX1002 or

MAX1003 controls the full-scale input range for both the

I and the Q channels. Jumper JU5 is used to manually

select the desired gain range as shown in Table 2. The

EV kits are shipped with the mid-gain range selected

(jumper pins open).

JU11

Open

Power Requirements

Both the MAX1002 and the MAX1003 require +5V at

about 65mA for their analog V

supply. Power-supply

requirements for the digital outputs, however, are differ-

ent for the two devices. 0Ω resistors are installed at

jumper sites JU1, JU2, JU6, and JU7, and can be

removed to sense device power-supply currents with

an ammeter.

Table 2. Gain-Selection Jumper JU5

Settings

JU5 SETTING

JU5

CONNECTION

ADC GAIN RANGE

Pins 1 and 2 shorted

Low-gain, 500mVp-p

MAX1003 Digital Outputs Supply

The MAX1003 requires +3.3V for the V

CCO

supply. The

current requirement from the power supply is a function

of the sampling clock and analog input frequencies, as

well as the capacitive loading on the digital outputs.

With 15pF loads and a 20MHz analog input frequency

sampled at 90Msps, the current draw is about 10mA.

JU5

No pins shorted

Mid-gain, 250mVp-p

JU5

Pins 2 and 3 shorted

High-gain, 125mVp-p

_______________________________________________________________________________________

MAX1002/MAX1003 Evaluation Kits

Table 3 lists the possible input-drive combinations for

the mid-gain (250mVp-p) full-scale range selection.

Drive levels are referenced to the open-circuit, com-

mon-mode voltage of the analog inputs (typically

2.35V) if DC coupled, or to ground if AC coupling is

used. If the low-gain (500mVp-p) range is selected, the

input-drive requirements are twice those listed in Table

3. If the high-gain (125mVp-p) range is selected, the

input-drive requirements are half those listed in Table 3.

Evaluate: MAX1002/MAX1003

FREQUENCY (MHz)

Table 3. Typical Input-Drive Requirements

for Mid-Gain

INPUT DRIVE

Single-Ended

Noninverting

QIN+ or IIN+

+125mV

-125mV

Open Circuit

Single-Ended

Inverting

Open Circuit

+62.5mV

Differential

-62.5mV

QIN- or IIN-

Open Circuit

+125mV

-125mV

-62.5mV

+62.5mV

OUTPUT

CODE

111111

100000

000000

011111

111111

100000

000000

VTUNE CONTROL VOLTAGE (V)

Figure 1. MAX1002 Oscillator Frequency vs. VTUNE Control

Voltage

105

100

FREQUENCY (MHz)

VTUNE CONTROL VOLTAGE (V)

Offset-Correction Amplifiers

The offset-correction amplifiers included on the

MAX1002 and MAX1003 are usually enabled in a typi-

cal AC-coupled application circuit. For DC-coupled

applications, the amplifiers must be disabled by

installing shorting blocks on jumpers JU3, JU4 (I chan-

nel); and JU8, JU9 (Q channel). These jumpers short

device pins IOCC+ (pin 2), IOCC- (pin 3), QOCC- (pin

16), and QOCC+ (pin 17) to ground and disable the

amplifiers. The MAX1002/MAX1003 EV kits are config-

ured with the offset-correction amplifiers enabled

(jumpers open) and AC-coupled analog inputs.

Figure 2. MAX1003 Oscillator Frequency vs. VTUNE Control

Voltage

Voltage-Controlled-Oscillator Operation

The EV kits include a voltage-controlled-oscillator

(VCO) circuit to set the analog-to-digital converter

(ADC) sampling rate using an external resonant tank

and a varactor diode. A voltage applied to the VTUNE

pad changes the varactor diode’s capacitance to

adjust the tank’s resonant frequency, which sets the

oscillator’s sampling frequency. VTUNE voltage can be

varied from 0V to a maximum of 8V.

The EV kits are designed so that a nominal VTUNE con-

trol voltage of about 4V sets the ADC sampling rate to

either 60Msps for the MAX1002 or 90Msps for the

MAX1003. The VTUNE control voltage should be well

filtered, as any noise on the supply contributes to jitter

in the internal oscillator and degrades the converters’

dynamic performance. Figures 1 and 2 show the

VTUNE control-voltage typical frequency-adjustment

ranges for the MAX1002 and MAX1003 EV kits, respec-

tively.

_______________________________________________________________________________________

MAX100/1003-fig2

110

MAX100/1003-fig1

MAX1002/MAX1003 Evaluation Kits

Evaluate: MAX1002/MAX1003

Table 4. External Clock Source EV Kit

Modifications

COMPONENT

Clock Overdrive

DESCRIPTION

Clock input BNC

connector

5pF capacitor (MAX1003),

22pF capacitor (MAX1002)

47pF capacitors

220nH inductor

10kΩ resistor

47kΩ resistors

Varactor diode

MODIFICATION

Add

Remove

Replace with

0.01µF capaci-

tors

Remove

Replace with

49.9Ω resistors

Remove

Digital Outputs

The TTL/CMOS-compatible digital outputs are present-

ed in parallel from both I and Q channels at connector

J1. The data format is offset binary with the MSB as D5

and the LSB as D0. The row of pins closest to the

board edge is digital output ground (OGND), while the

data bits occupy the inside row. Located in the middle

of the connector is the pin for the output clock labeled

DCLK. This signal can be used to latch the parallel out-

put data for capture into a logic analyzer or external

DSP circuitry. Both digital outputs are updated on

DCLK’s rising edge (see the timing diagram in the

MAX1002 or MAX1003 data sheet).

C6, C7

R2, R3

_____________Layout Considerations

The MAX1002/MAX1003 EV kit layouts have been opti-

mized for high-speed signals. Careful attention has

been given to grounding, power-supply bypassing, and

signal-path layout to minimize coupling between the

analog and digital sections of the circuit. For example,

the ground plane has been removed under the tank cir-

cuitry to reduce stray capacitive loading on the relative-

ly small capacitors required in the external resonant

tank formed by C5, L1, and D1. Other layout considera-

tions are detailed in the following sections.

External Clock Operation

The MAX1002/MAX1003 EV kits can be converted to

drive the ADCs from an external clock source. This

involves removing the external resonator components

from the VCO circuit and adding a few new compo-

nents. Table 4 lists the EV kit changes required to con-

vert the board to accept an external clock source. The

resulting schematic is shown in Figure 4.

The new 49.9Ω value of R3 shown in Figure 4 provides

proper termination for a 50Ω external signal generator.

AC-coupling capacitor C6 couples the external clock

signal to the MAX1002/MAX1003 oscillator circuitry at

TNK+ (pin 9). R2 and C7 ensure that the impedance at

both ports of the oscillator is balanced. After all modifi-

cations are complete, connect an external clock source

to the BNC connector on the EV kit marked CLOCK

OVERDRIVE. The recommended clock amplitude is

1Vp-p; however, the ADC operates correctly with as lit-

tle as 100mVp-p or up to 2.5Vp-p on CLOCK OVER-

DRIVE.

The external clock source should have low phase noise

for best dynamic performance. A low-phase-noise

sine-wave oscillator serves this purpose well. A square-

wave clock source is not necessary to drive the

MAX1002/MAX1003. The devices contain sufficient

gain to amplify even a low-level-input sine wave to drive

the ADC comparators, while ensuring excellent dynam-

ic performance.

Power Supplies and Grounding

The EV kits feature separate analog and digital power

supplies and grounds for best dynamic performance. A

thin trace located on the backside of the circuit board

near the VCC power-supply connector ties the analog

and output ground planes together. This trace can be

cut if the power-supply grounds are referenced else-

where.

Referencing analog and digital grounds together at a

single point usually avoids ground loops and corruption

of sensitive analog circuitry by noise from the digital

outputs. If the ground trace on the backside of the

board is cut, observe the absolute maximum ratings

between the two grounds.

_______________________________________________________________________________________

MAX1002/MAX1003 Evaluation Kits

Bypassing

Proper bypassing is essential to achieve the best

dynamic performance from the converters. The

MAX1002/MAX1003 EV kits use 10µF bypass capaci-

tors located close to the power-supply connectors on

the board to filter low-frequency supply ripple. High-fre-

quency bypassing is accomplished with ceramic chip

capacitors located very close to the device’s supply

pins.

As the digital outputs toggle, transient currents in the

CCO

supply can couple into sensitive analog circuitry

and severely degrade the converters’ effective number

of bits performance. Of particular concern is effectively

bypassing V

CCO

to OGND. For best results, locate the

bypass capacitors on the same side of the board and

place them close to the device. This avoids the use of

through-holes and results in lower series inductance.

The capacitor size chosen for the EV kits (size 0603)

keeps the layout compact. Finally, the modest value

(47pF) and small size result in a high self-resonant fre-

quency for effective high-frequency bypassing.

__________Applications Information

To achieve the full dynamic potential from the convert-

ers, minimize the capacitive loading on the digital out-

puts to reduce the transient currents at V

CCO

and

OGND. The maximum capacitance per output bit

should be less than 15pF. For example, the capaci-

tance of the digital output traces and the J1 connector

on the EV kits is about 3pF per trace. In an applications

circuit, this could be further reduced by locating the

digital receiving chip very close to the MAX1002/

MAX1003 and removing the ground plane from under

the output bit traces.

A logic analyzer can be connected to the J1 connector

on the EV kits for evaluation purposes. The analyzer

should be directly connected to the EV kit without any

additional ribbon cables. Even a short length of ribbon

cable can exceed the maximum recommended capaci-

tive loading of the digital outputs. A typical high-speed

logic analyzer probe adds about another 8pF loading

per digital bit, which is acceptable for good dynamic

performance.

Evaluate: MAX1002/MAX1003

_______________________________________________________________________________________

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