Maxim MAX9993 User Manual

General Description

The MAX9993 evaluation kit (EV kit) simplifies the evalua­tion of the MAX9993 UMTS, DCS, and PCS base-station
downconversion mixer. It is fully assembled and tested
at the factory. Standard 50Ω SMA connectors are
included on the EV kit for the input and output to allow
quick and easy evaluation on the test bench.

This document provides a list of equipment required to
evaluate the device, a straight-forward test procedure
to verify functionality, a description of the EV kit circuit,
the circuit schematic, a bill of materials (BOM) for the
kit, and artwork for each layer of the PC board.

Contact MaximDirect sales at 888-629-4642 to check
on pricing and availibility for these kits.

Features

♦ Fully Assembled and Tested

♦ +23.5dBm Input IP3

♦ 1700MHz to 2200MHz RF Frequency

♦ 1400MHz to 2000MHz LO Frequency

♦ 40MHz to 350MHz IF Frequency

♦ 8.5dB Conversion Gain

♦ 9.5dB Noise Figure

♦ Integrated LO Buffer

♦ Switch-Selectable (SPDT), Two LO Inputs

♦ Low 0dBm to +6dBm LO Drive

♦ 40dB LO1 to LO2 Isolation

Evaluates: MAX9993

MAX9993 Evaluation Kit

________________________________________________________________ Maxim Integrated Products 1

19-2706; Rev 0; 11/02

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

*EP = Exposed paddle.

Component Suppliers

Component List

**The exposed paddle conductor on U1 must be solder attached
to a grounded pad on the circuit to ensure a proper electrical/
thermal design.

SUPPLIER PHONE WEBSITE

Coilcraft 800-322-2645 www.coilcraft.com

Digi-key 800-344-4539 www.digikey.com

Johnson 507-833-8822 www.johnsoncomponents.com

Mini-Circuits 718-934-4500 www.minicircuits.com

Murata 770-436-1300 www.murata.com

DESIGNATION QTY DESCRIPTION

4.0pF ±0.25pF, 50V C0G-type

C1 1

C2, C6, C7,

C9, C10

C3, C5, C8 3

C4 1

C11, C12, C13 3

J1–J4 4

L1, L2 2

ceramic capacitor (0603)
Murata GRM1885C1H4R0C

22pF ±5%, 50V C0G-type ceramic
capacitors (0603)

5

Murata GRM1885C1H220J

0.01µF ±10%, 50V X7R-type ceramic
capacitor (0603)
Murata GRM188R71H103K

10pF ±5%, 50V C0G-type ceramic
capacitor (0603)
Murata GRM1885C1H100J

150pF ±5%, 50V C0G-type ceramic
capacitors (0603)
Murata GRM1885C1H151J

PC board edge-mount SMA RF
connectors (flat tab launch)
Johnson 142-0741-856

470nH ±5% wi r e-w ound i nd uctor s ( 1008)
Coilcraft 1008CS-471XJBC

PART TEMP RANGE IC PACKAGE

MAX9993EVKIT -40°C to +85°C

DESIGNATION QTY DESCRIPTION

L3 1

R1 1 523Ω ±1% resistor (0603)

R2 1 383Ω ±1% resistor (0603)

R3, R4 2

R5 1 200Ω ±5% resistor (0603)

R6 1 47kΩ ±5% resistor (0603)

T1 1

TP1 1

TP2 1

TP3 1

U1 1 MAX9993ETP-T**

Thin QFN 20-EP*

(5mm x 5mm)

10nH ± 5% w i r e- w ound i nd uctor ( 0805)
Coilcraft 0805CS-100XJBC

7.15Ω ±1% resistors (1206)
Digi-key 311-7.15FCT-ND

4:1 transformer (200:50)
Mini-Circuits TC4-1W-7A

Large test point for 0.062in
PC board (red) Mouser 151-107

Large test point for 0.062in
PC board (black) Mouser 151-103

Large test point for 0.062in
PC board (white) Mouser 151-101

Evaluates: MAX9993

MAX9993 Evaluation Kit

2 _______________________________________________________________________________________

Quick Start

The MAX9993 EV kit is fully assembled and factory test­ed. Follow the instructions in the Connections and
Setup section for proper device evaluation.

Test Equipment Required

Table 1 lists the equipment required to verify the opera­tion of the MAX9993 EV kit. It is intended as a guide
only, and some substitutions are possible.

Connections and Setup

This section provides a step-by-step guide to testing
the basic functionality of the EV kit. As a general pre­caution to prevent damaging the outputs by driving
high-VSWR loads, do not turn on DC power or RF

signal generators until all connections are made.

This procedure is specific to operation in the U.S. PCS
band (reverse channel: 1850MHz to 1910MHz), low­side injected LO for a 200MHz IF. Choose the test fre­quency based on the particular system’s frequency
plan, and adjust the following procedure accordingly.
See Figure 1 for the mixer test setup diagram.

1) Calibrate the power meter for 1700MHz. For safety
margin, use a power sensor rated to at least
+20dBm, or use padding to protect the power head
as necessary.

2) Connect 3dB pads to the DUT ends of each of the
three RF signal generators’ SMA cables. This
padding improves VSWR, and reduces the errors
due to mismatch.

3) Use the power meter to set the RF signal generators
according to the following:

• RF signal source: -5dBm into DUT at 1900MHz
(this will be about -2dBm before the 3dB pad)

• LO1 signal source: +3dBm into DUT at 1700MHz
(this will be about +6dBm before the 3dB pad)

• LO2 signal source: +3dBm into DUT at 1701MHz
(this will be about +6dBm before the 3dB pad)

4) Disable the signal generator outputs.

5) Connect the RF source (with pad) to RF IN.

6) Connect the LO1 and LO2 signal sources to the EV
kit LO inputs.

7) Measure loss in the 3dB pad and the cable that will
be connected to IF OUT. Losses are frequency
dependent, so test this at 200MHz (the IF frequen­cy). Use this loss as an offset in all output
power/gain calculations.

8) Connect this 3dB pad to the EV kit’s IF OUT connec­tor, and connect a cable from the pad to the spec­trum analyzer.

9) Set DC supply to +5.0V, and set a current limit
around 250mA if possible. Disable the output volt­age and connect the supply to the EV kit through
the ammeter. Enable the supply. Re-adjust the sup­ply to get +5.0V at the EV kit. There will be a voltage
drop across the ammeter when the mixer is drawing
current.

10) Select LO1 by connecting LOSEL (TP3) to GND.

11) Enable the LO and the RF sources.

Testing the Mixer

Adjust the center and span of the spectrum analyzer to
observe the IF output tone at 200MHz. The level should
be about +0.5dBm (8.5dB conversion gain, 3dB pad
loss). There will also be a tone at 199MHz, which is due to
the LO signal applied to LO2. The amount of suppression
between the 200MHz and 199MHz signals is the switch
isolation. The spectrum analyzer’s absolute magnitude
accuracy is typically no better than ±1dB. Use the power
meter to get an accurate output power measurement.

Disconnect the GND connection to LOSEL. It will be
pulled high by a pullup resistor on the board, selecting
LO2. Observe that the 199MHz signal increases while
the 200MHz decreases.

Reconfigure the test setup using a combiner or hybrid
to sum the two LO inputs to do a 2-tone IP3 measure­ment if desired. Terminate the unused LO input in 50Ω.

Detailed Description

The MAX9993 is a highly integrated downconverter. RF
and LO baluns are integrated on-chip, as well as an LO
buffer and a SPDT LO input select switch. The EV kit cir­cuit consists mostly of supply decoupling capacitors and
DC-blocking capacitors, allowing for a simple design-in.

Supply Decoupling Capacitors

Capacitors C2, C6, and C7 are 22pF (±5%) high-fre­quency supply decoupling capacitors necessary to keep

Table 1. Test Equipment

EQUIPMENT QTY DESCRIPTION

HP E3631A 1 DC power supply

Fluke 75 Series II 1 Digital multimeter (ammeter)

HP/Agilent 8648B 3 RF signal generators

HP 437B 1 RF power meter

HP 8482A 1 High-power sensor (power head)

HP 8561 1 Spectrum analyzer

3dB Pad 4 3dB attenuators

50Ω Termination 1 50Ω (1W) termination

high-frequency noise from coupling back into the supply.
Capacitors C3 and C8 are larger 0.01µF ceramics used
for filtering lower frequency noise on the supply.

DC-Blocking Capacitors

The MAX9993 has internal baluns on the RF, LO1 and
LO2 inputs. These inputs have almost 0Ω resistance at
DC, and so DC-blocking capacitors C1, C9, and C10
are used to prevent any external bias from being shunt­ed directly to ground. Capacitors C12 and C13 are
used to keep DC current from flowing into the trans­former, as well as providing the flexibility for matching.

LO BIAS and IF BIAS

Bias currents for the integrated IF output amplifier and
the LO buffer are set with resistors R1 (523Ω, ±1%) and
R2 (383Ω, ±1%), respectively. These values were care­fully chosen for best linearity and lowest supply current
through testing at the factory. Changing these values,
or using lower tolerance resistors, degrades perfor­mance.

Current-Limiting Resistors

Resistors R3 and R4 are used for current limiting at the
supply. Resistor R3 dissipates 80mW and R4 dissi­pates 125mW.

TAP Network

The network at TAP formed by R5 and C5 helps to ter­minate the second-order intermodulation products at
the RF input to balance the upper and lower side-band
input IP3 performance.

LEXT

The 10nH (±5%) wire-wound inductor, L3, improves
LO-to-IF and RF-to-IF isolation. If isolation is not critical,
then this pin can be grounded.

IF±

The MAX9993 employs a differential IF output to offer
increased IP2 system performance. The EV kit uses a
4:1 balun to transform the 200Ω differential output
impedance to a 50Ω single-ended output for easy
bench evaluation. Inductive pullups L1 and L2 provide
DC bias to the IF output amplifier, using C11 for supply
filtering and R4 for current limiting. Series capacitors
C12 and C13 work in conjunction with the inductors
and the 4:1 balun transformer (T1) to match the IF out­put for 40MHz to 200MHz operation.

As the differential IF outputs are relatively high imped­ance (200Ω), they are more susceptible to component
parasitics. It is often good practice to relieve the
ground plane directly underneath large components to
reduce associated shunt-C parasitics.

LO_SEL

The EV kit includes a 47kΩ pullup resistor for easy
selection of the LO port. Providing a ground at TP3
selects LO1, and leaving TP3 open selects LO2. To
drive TP3 from an external source, follow the limits
called out in the MAX9993 device data sheet. Logic
voltages should not be applied to TP3 without the +5V
supply applied. Doing so can cause the on-chip ESD
diodes to conduct and could damage the part.

Layout Considerations

The MAX9993 evaluation board can be a guide for your
board layout. Pay close attention to thermal design and
close placement of components to the IC. The MAX9993
package exposed paddle (EP) conducts heat from the
device and provides a low-impedance electrical connec­tion to the ground plane. The EP must be attached to the
PC board ground plane with a low thermal and electrical
impedance contact. Ideally, this is achieved by soldering
the backside of the package directly to a top metal
ground plane on the PC board. Alternatively, the EP can
be connected to an internal or bottom-side ground plane
using an array of plated vias directly below the EP.

Depending on the ground plane spacing, large sur­face-mount pads in the IF path may need to have the
ground plane relieved under them to reduce parasitic
shunt capacitance.

Modifying the EV Kit

The RF and LO inputs are broadband matched, so
there is no need to modify the circuit for use anywhere
in the 1700MHz to 2200MHz RF range (1400MHz to
2000MHz LO range).

Retuning for a different IF is as simple as scaling the
values of the IF pullup inductors up or down with fre­quency. The IF output looks like 200Ω differential in
parallel with a capacitor. The capacitance is due to the
combination of the IC, PC board, and external IF com­ponents. The capacitance is approximately 4pF (per
output) to ground. This capacitance is resonated out at
the frequency of interest by the bias inductors L1 and
L2. To determine the inductor value use the following
equation:

The IF output is tuned for operation at approximately
100MHz, so a 470nH inductor is used. For lower IF fre­quencies (i.e., larger component values), maintain the
component’s Q value at the cost of larger case size,
unless it is unavoidable.

f

LxC

IF

=

1

2π

Evaluates: MAX9993

MAX9993 Evaluation Kit

_______________________________________________________________________________________________________ 3

Evaluates: MAX9993

MAX9993 Evaluation Kit

4 _______________________________________________________________________________________

Figure 1. Test Setup Diagram

RF SIGNAL GENERATOR

(HP 8648B)

1900.000MHz

RF SIGNAL GENERATOR

(HP 8648B)

1700.000MHz

3dB

RF IN

MULTIMETER HPIB

U1

BENCH

(HP 34401A)

202mA

(AMMETER)

+5V

GND

POWER SUPPLY

3-OUT, HPIB
(AG E3631A)

5.0V 250mA (MAX)

-+ -+

RF SIGNAL GENERATOR

(HP 8648B)

1701.000MHz

3dB

LO1

3dB

LO2

RF POWER METER

(GIGA 80701A,

MAX9993

HP 437B)

IF OUT

POWER SENSOR

3dB

RF HIGH-

RF SPECTRUM ANALYZER

(HP 8561x)

Evaluates: MAX9993

MAX9993 Evaluation Kit

_______________________________________________________________________________________ 5

Figure 2. MAX9993 EV Kit Schematic

SMA

RF IN

J1

7.15Ω

5.0V

R3

0.01µF

R5

200Ω

C12

150pF

5.0V

J2
SMA
IF OUT

TP1
+5V

TP2
GND

J4
SMA
LO2

J3
SMA
LO1

TP3
LOSEL

18

8

47kΩ

GND

17

MAX9993

9

LOSEL

R6

L1
470nH

L2
470nH

C13

150pF

LEXT

10nH

16

U1

10

GND

R4

7.15Ω

C11

150pF

R1

523Ω

5.0V

IF+

C3

0.01µF

C5

0.01µF

R2
383Ω

5.0V

C8

C2
22pF

C1

4.0pF

C4
10pF

C6
22pF

GND

GND

22pF

V

TAP

C7

CC

RF

IFBIAS

1

2

3

4

5

IF-

20

19

6

7

CC

V

LOBIAS

CC

V

T1

63

4:1 (200:50)

2

TRANSFORMER

4

1

5.0V

L3

C10

LO2

15

GND

14

GND

13

GND

12

LO1

11

22pF

C9

22pF

Evaluates: MAX9993

MAX9993 Evaluation Kit

6 _______________________________________________________________________________________

Figure 5. MAX9993 EV Kit PC Board Layout—Top Layer Metal

Figure 3. MAX9993 EV Kit PC Board Layout—Top Silkscreen

Figure 4. MAX9993 EV Kit PC Board Layout—Top Soldermask

Figure 6. MAX9993 EV Kit PC Board Layout— Inner Layer 2
(GND)

1.0"

1.0"

1.0"

1.0"

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7

© 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Evaluates: MAX9993

MAX9993 Evaluation Kit

Figure 9. MAX9993 EV Kit PC Board Layout—Bottom
Soldermask

Figure 10. MAX9993 EV Kit PC Board Layout—Bottom
Silkscreen

Figure 7. MAX9993 EV Kit PC Board Layout—Inner Layer 3
(Routes)

Figure 8. MAX9993 EV Kit PC Board Layout—Bottom Layer
Metal

1.0"

1.0"

1.0"

1.0"