General Description

The MAX2740 evaluation kit (EV kit) simplifies testing of
the MAX2740 GPS receiver. This kit allows evaluation of
the device's LNA, mixers, variable gain amplifier (VGA),
fixed gain amplifier, voltage-controlled oscillator (VCO),
and synthesizer.

The EV kit provides 50

SMA connectors for all signal

inputs and outputs. A varactor-based tank circuit is pro-
vided for the on-chip VCO and is phase locked with the
on-chip phase-locked loop (PLL).

Features

o Differential Baseband Outputs
o +2.7V to +3.3V Single-Supply Operation
o SMA Connectors on All Signal Ports

Evaluates: MAX2740

MAX2740 Evaluation Kit

________________________________________________________________ Maxim Integrated Products

19-1670; Rev 0; 7/00

Component List

For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.

DESIGNATION

QTY

DESCRIPTION

10µF

±10% tantalum capacitor

AVX TAJC106K016R

C2, C10, C14,

C18, C20, C21,
C32, C33, C35,
C36, C37, C38,

C43

1000p F

± 10% cer am i c cap aci tor s

(0402)
Murata GRM36X7R102K050A

12pF

±5% ceramic capacitor

(0402)
Murata GRM36COG120J050A

C4, C8, C16,

C22

-C31,

0.015

µF ±10% cer am i c cap aci tor s

(0402)
Murata GRMX5R153K016A

C5, C7, C13,

C15, C17, C19,

C39

100pF

±5% ceramic capacitors

(0402)
Murata GRM36COG101J050A

7pF

±0.1pF ceramic capacitor

(0402)
Murata GRM36COG070B050A

C9, C12, C41,

C45, C46, C47

Leave sites open

Ordering Information

PART

TEMP.RANGE

IC PACKAGE

MAX2740EVKIT

-40

°C to +85°C

48 TQFP-EP*

DESIGNATION

QTY

DESCRIPTION

C40

2.7pF

±0.1pF ceramic capacitor

(0402)
Murata GRM36COG2R7B050A

C42

3pF

±0.1pF ceramic capacitor

(0402)
Murata GRM36COG030B050A

C44

2pF

±0.1pF ceramic capacitor

(0402)
Murata GRM36COG020B050A

BBY 51-03W Siemens tuning
diode

100

variable resistor

Bourns 3796W Digi-Key

R3, R4

100

±5% resistors (0402)

R5, R8

12.1k

±1% resistors (0402)

R6, R7, R9, R10

2.74k

±1% resistors (0402)

R11, R12

1.21k

±1% resistors (0402)

R13

-R18

±1% resistors (0402)

R19

453

±1% resistor (0402)

R20

15k

±1% resistor (0402)

L1, L2, L5

220nH inductors
Toko LL1608-FSR22J

L8, L9

8.2nH inductors
Toko LL1608-FH8N2K

Leave site open

L10

1.8nH inductor
Murata LQP10A1N8B00

L11, L12

resistors (0603)

*Exposed Paddle

Evaluates: MAX2740

MAX2740 Evaluation Kit

_______________________________________________________________________________________

Quick Start

The MAX2740 EV kit is fully assembled and factory test-
ed. Follow the instructions in the Connections and
Setup section. Table 1 lists the test equipment recom-
mended to verify MAX2740 operation. This list is intend-
ed as a guide only; substitutions may be possible.
Figure 1 shows the MAX2740 EV kit schematic.

Connections and Setup

The customer has the option of closing the PLL loop or
externally driving the LO. The PLL loop is closed on the
assembled EV kit. To externally drive the LO, remove
L10 and place C9. A 1440MHz, -10dBm signal is
required at the TANK SMA connector. Perform the fol-
lowing steps to evaluate the MAX2740:

1) Verify that jumpers JU1, JU2, and JU7, JU8, JU9

are in place.

2) Connect V

and GND. Set the supply voltage to

+3.0V. When the power is turned on, the current
should be approximately 55mA.

3) For evaluation of the LNA gain, first calibrate the

setup for cable losses. Connect the signal genera-
tor with 1575.42MHz at -30dBm to LNA_IN.
Connect LNA_OUT to the spectrum analyzer. The
measured power gain will be approximately 16dB.

4) Repeat the calibration procedure (step 3) for use on

the RF mixer. Connect the 1575.42MHz (-30dBm)
signal source to the RFMIX_IN+. Connect
RFMIX_OUT+ and RFMIX_OUT- through the balun
to the spectrum analyzer. At 135MHz, losses due to
the Anzac balun are approximately 0.65dB. The
measured power gain should be approximately
22dB. If a balun is unavailable, a single-ended
measurement of the output can be taken. Terminate
the unused output in 50

, and add 3dB to the final

output power measurement.

5) Repeat the calibration procedure (step 3) for use

on the IF mixer. Use the baluns on the input and
output to allow a fully differential measurement.
Connect IFMIX_IN+ and IFMIX_IN- through one
balun to the 135.42MHz (-47dBm) signal source.
Connect IFMIX_OUT+ and IFMIX_OUT- through the
second balun to the spectrum analyzer. At 135MHz,
losses due to the Anzac balun are approximately
0.65dB, and at 15MHz, the losses are approximately
0.3dB. For gain calculation, the attenuation due to

Component List (continued)

DESIGNATION

QTY

DESCRIPTION

MAX2740ECM 48-pin TQFP-EP*

MAX4122EUK SOT23-5

-J22

SMA connectors (PC mount)
Johnson 142-0701-201 or
Digi-Key J500-ND

JU1

-JU4, JU7,

JU8, JU9

2-pin headers

VCC, GND

Test points
Digi-Key 5000K-ND

MAX2740 EV kit circuit board,
Rev. B

MAX2740 data sheet

Component Suppliers

SUPPLIER

PHONE

FAX

AVX

803-946-0690

803-626-3123

Coilcraft

847-639-6400

847-639-1469

Digi-Key

218-681-6674

218-681-3380

Infineon

408-501-6000

408-501-2424

Murata

949-852-2001

949-852-2002

Toko

708-297-0070

708-699-1194

Note: Please indicate that you are using the MAX2740 when
contacting these component suppliers.

Table 1. Recommended Test Equipment

EQUIPMENT

DESCRIPTION

RF Signal
Generators (2)

One HP 8648C or equivalent
and one HP 83712A or equivalent.
These should be capable of
delivering -70dBm to 0dBm of
output power in the 10MHz to
2000MHz frequency range. The
HP 8648C is required to test the
receive signal path, and the HP
83712A is a low-phase noise
sour ce for the r efer ence fr eq uency.

Power Supply

Capable of providing at least
100mA at +2.7V to +3.3V

Spectrum Analyzer

HP 8561E

Balun (2)

M/A Com Anzac 96341

Extra Voltage Source

For external control of VGA
functions

*Note: U1 has an exposed paddle that requires it to be solder
attached to the circuit board to ensure proper functionality of
the part.

the 2k

load resistor on each output must be taken

into account. The total differential gain calculation,
assuming two baluns, is:

where:

The measured power gain should be approximately
36dB.

6) To control the VGA gain, connect the second power

supply to the nongrounded terminal of jumper JU3,
and open jumper JU4. The VGA gain will be evalu-
ated at V

= 0.5V and 2.5V. It is important to note

that the VGA gain and subsequent FGA gain are
voltage-gain measurements. Repeat the calibration
procedure as before (step 3). Connect VGA_IN+
and VGA_IN- through one balun to the 15.42MHz
(-27dBm) signal source. Connect VGA_OUT+ and
VGA_OUT- through the second balun to the spec-
trum analyzer. At 15.42MHz, losses due to the
Anzac balun are approximately 0.3dB. For gain cal-
culation, the attenuation due to the 2k

load resis-

tor on each output must be taken into account. The
total differential gain calculation, assuming two
baluns, is:

where:

The measured voltage gain at V

= 2.5V should

be approximately 15dB. The gain range should be
more than 50dB.

7) The FGA procedure will be similar to the VGA,

minus the need for the second voltage source.
Repeat the calibration procedure as before (step
3). Connect FGA_IN+ and FGA_IN- through one
balun to the 15.42MHz (-43dBm) signal source.
Connect FGA_OUT+ and FGA_OUT- through the
second balun to the spectrum analyzer. At
15.42MHz, losses due to the Anzac balun are
approximately 0.3dB. Calculations are identical to
that of the VGA. The measured voltage gain should
be approximately 40dB.

Adjustments and Control

The MAX2740 EV kit is configured with a 100k

trim pot

for setting and adjusting the VGA gain. To use an exter-
nal supply, remove the 2-pin series and shunt jumpers
(JU3 and JU4). Connect the supply directly to the
nongrounded terminal of JU3.

Detailed Description

The following sections cover the EV kit's circuit blocks
in detail. (Refer to the MAX2740 data sheet for addition-
al information.)

LNA

The LNA is a two-stage amplifier using feedback to set
the gain. The circuit requires input and output match-
ing. It is externally biased through the output matching
network.

RF MIXER

The RF mixer is a double-balanced Gilbert cell with
local LO drive provided from a low-impedance differen-
tial pair. The second RF input is brought out to a sepa-
rate pin for external decoupling on pin 7. The IF output
is delivered through low-output-impedance emitter fol-
lowers. The input is matched to 50

, and the outputs

are individually matched to 50

(100 differential).

The mixer is intended to drive a 400

SAW filter.

IF MIXER

The IF mixer is very similar to the RF mixer, except the
IF mixer input is fully differential. The emitter follower
outputs are intended to drive directly into a high-imped-
ance, differential, 3-pole lowpass filter made up of dis-
crete components.

Evaluates: MAX2740

MAX2740 Evaluation Kit

_______________________________________________________________________________________

IN(MEAS)

LOSS(BALUN AT 135MHz)

OUT

OUT(MEAS)

LOSS(BALUN AT 15MHz)

LOSS(LOAD)

32.3dB

Power_Gain = P

LOSS(LOAD)

OUT

100

4100

log

IN(MEAS)

LOSS(BALUN AT 15MHz)

OUT

OUT(MEAS)

LOSS(BALUN AT 15MHz)

LOSS(LOAD)

32.3dB

Voltage_Gain=P

6dB

LOSS(LOAD)

OUT

100

4100

log

Evaluates: MAX2740

MAX2740 Evaluation Kit

_______________________________________________________________________________________

VGA and FGA

The inputs and outputs of both circuits are differential.
The VGA has a useful gain-control range of >50dB. The
FGA was designed to deliver 40dB of differential gain
at the second IF frequency of 15.42MHz. In the appli-
cation, the FGA differential inputs are received from the
VGA outputs through a balanced lowpass filter circuit.
The FGA's differential output is designed to drive a dig-
itizer with a typical load impedance of 4k

differential.

PC Board Layout/Construction

The MAX2740 EV kit can serve as a board layout guide.
Keep PC board trace lengths as short as possible to
minimize parasitics. Keep decoupling capacitors close
to the device, with a low inductance via connection to
the ground plane. The GLSOUT signal must not be
routed parallel to the REF input to avoid loss of frequen-
cy lock due to coupling between the two signals.

The MAX2740 EV kit PC board uses 14mil-wide traces
for 50

traces. The PC board has an 8mil layer profile

to the ground plane on FR4, with a dielectric constant
of 4.5, and 75mil trace-to-ground-plane spacing.

Evaluates: MAX2740

MAX2740 Evaluation Kit

_______________________________________________________________________________________

GND

IFMIX_OUT+

VGA_IN+

VGA_OUT+

FGA_IN+

FGA_OUT+

FGA_IN-

VGA_OUT-

VGA_IN-

IFMIX_OUT-

GND_2LNA

LNA_IN

GND_1LNA

GND_AMIX

GND_ANA

GND

FRMIX_IN-

IFRMIX_OUT-

FRMIX_OUT+

IFMIX_IN+

IFMIX_IN-

IFRMIXN_OUT

FRMIX_OUT

IFMIX_IN

IFMIXN_IN

VCCRF_MIX

VCCIF_MIX

GNDIF_MIX

FRMIX_IN+

GND

LNA_OUT

GLS_OUT

REF_IN

FGA_OUT-

FGAN_OUT

DOWN

GND

GND_VCO

GND_DIG

VCC_DIG

TANK

AGCON

VCC_ANA

VCC_VCO

IFMIX_OUT+

VGA_IN+

VGA_OUT+

FGA_IN+

FGA_OUT+

FGA_IN-

VGA_OUT-

VGA_IN-

IFMIX_OUT-

C23

0.015

µF

R17

J8
SMA

C26

0.015

µF

R16

J11
SMA

C27

0.015

µF

R15

J12
SMA

C30

0.015

µF

R14

J15
SMA

C31

0.015

µF

R13

J16
SMA

C24

0.015

µF

J9
SMA

C25

0.015

µF

J10
SMA

C28

0.015

µF

J13
SMA

C29

0.015

µF

J14
SMA

MAX2740

+3V_VCO

+3V_AN

C7
100pF

C8
0.015

µF

+3VA

100k

JU3

JU4

7pF

SMA

NO_LOAD

MAX4122

C22
0.015

µF

R18

J7
SMA

C20
1000pF

R19

453

J5
SMA

J6
SMA

C21
1000pF

C9
OPEN

SMA

220nH

C16

0.015

µF

C17

100pF

+3VA

JU7

L10

1.8nH

12pF

R20
15k

C44
2pF

C13
100pF

D1
SIEMENS
BBY 51-03W

12.1k

100

C14

1000pF

C19
100pF

C15
100pF

2.74k

R10

2.74k

C18
1000pF

R8
12.1k

+3VA

J18

SMA

C33
1000pF

J22

SMA

C42
3pF

J17

SMA

C32
1000pF

C38
1000pF

R11
1.1k

C47

OPEN

C45

OPEN

J19

SMA

L11
0

C37

1000pF

R12
1.1k

C46

OPEN

C12

OPEN

J20

SMA

L12

C35

1000pF

+3VA

JU8

C39

100pF

+3VA

JU9

100

C41

OPEN

J21

SMA

C2
1000pF

C40

2.7pF

8.2nH

+3VA

8.2nH

C43

1000pF

+ C1

µF

+3VA_VCO

220nH

C10
1000pF

C4
0.015

µF

C5
100pF

+3VA

JU1

JU2

+3VA_AN

VCC

GND

IFMIX_OUT+

IFMIX_OUT-

RFMIX_OUT-

RFMIX_OUT+

LNA_OUT

LNA_IN

TANK

REF_IN

FGA_OUT_

GLS_OUT

Figure 1. MAX2740 EV Kit Schematic

Part Number MAX2740EVKIT