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19-1670; Rev 0; 7/00
MAX2740 Evaluation Kit
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 provided for the on-chip VCO and is phase locked with the on-chip phase-locked loop (PLL). o Differential Baseband Outputs o +2.7V to +3.3V Single-Supply Operation o SMA Connectors on All Signal Ports
Features
Evaluates: MAX2740
Ordering Information
PART MAX2740EVKIT TEMP.RANGE -40C to +85C IC PACKAGE 48 TQFP-EP*
*Exposed Paddle
Component List
DESIGNATION C1 C2, C10, C14, C18, C20, C21, C32, C33, C35, C36, C37, C38, C43 C3 QTY 1 DESCRIPTION 10F 10% tantalum capacitor AVX TAJC106K016R 1000pF 10% ceramic capacitors (0402) Murata GRM36X7R102K050A 12pF 5% ceramic capacitor (0402) Murata GRM36COG120J050A 0.015F 10% ceramic capacitors (0402) Murata GRMX5R153K016A 100pF 5% ceramic capacitors (0402) Murata GRM36COG101J050A 7pF 0.1pF ceramic capacitor (0402) Murata GRM36COG070B050A Leave sites open DESIGNATION C40 QTY 1 DESCRIPTION 2.7pF 0.1pF ceramic capacitor (0402) Murata GRM36COG2R7B050A 3pF 0.1pF ceramic capacitor (0402) Murata GRM36COG030B050A 2pF 0.1pF ceramic capacitor (0402) Murata GRM36COG020B050A BBY 51-03W Siemens tuning diode 100 variable resistor Bourns 3796W Digi-Key 100 5% resistors (0402) 12.1k 1% resistors (0402) 2.74k 1% resistors (0402) 1.21k 1% resistors (0402) 2k 1% resistors (0402) 453 1% resistor (0402) 15k 1% resistor (0402) 220nH inductors Toko LL1608-FSR22J 8.2nH inductors Toko LL1608-FH8N2K Leave site open 1.8nH inductor Murata LQP10A1N8B00 0 resistors (0603)
12
C42
1
1
C44
1
C4, C8, C16, C22-C31, C5, C7, C13, C15, C17, C19, C39
D1 R2 R3, R4 R5, R8 R6, R7, R9, R10 R11, R12 R13-R18 R19 R20 L1, L2, L5 L8, L9 L3 L10 L11, L12
1 1 2 2 4 2 6 1 1 3 2 1 1 2
13
7
C6 C9, C12, C41, C45, C46, C47
1
6
________________________________________________________________ Maxim Integrated Products
1
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.
MAX2740 Evaluation Kit Evaluates: MAX2740
Component List (continued)
DESIGNATION U1 U2 J3-J22 JU1-JU4, JU7, JU8, JU9 VCC, GND -- -- QTY 1 1 20 DESCRIPTION MAX2740ECM 48-pin TQFP-EP* MAX4122EUK SOT23-5 SMA connectors (PC mount) Johnson 142-0701-201 or Digi-Key J500-ND 2-pin headers Test points Digi-Key 5000K-ND MAX2740 EV kit circuit board, Rev. B MAX2740 data sheet Power Supply Spectrum Analyzer Balun (2) Extra Voltage Source RF Signal Generators (2)
Table 1. Recommended Test Equipment
EQUIPMENT DESCRIPTION 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 source for the reference frequency. Capable of providing at least 100mA at +2.7V to +3.3V HP 8561E M/A Com Anzac 96341 For external control of VGA functions
7 2 1 1
*Note: U1 has an exposed paddle that requires it to be solder attached to the circuit board to ensure proper functionality of the part.
Component Suppliers
SUPPLIER AVX Coilcraft Digi-Key Infineon Murata Toko PHONE 803-946-0690 847-639-6400 218-681-6674 408-501-6000 949-852-2001 708-297-0070 FAX 803-626-3123 847-639-1469 218-681-3380 408-501-2424 949-852-2002 708-699-1194
2) Connect VCC 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 generator 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
Note: Please indicate that you are using the MAX2740 when contacting these component suppliers.
Quick Start
The MAX2740 EV kit is fully assembled and factory tested. Follow the instructions in the Connections and Setup section. Table 1 lists the test equipment recommended to verify MAX2740 operation. This list is intended 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 following steps to evaluate the MAX2740: 1) Verify that jumpers JU1, JU2, and JU7, JU8, JU9 are in place.
2
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MAX2740 Evaluation Kit
the 2k load resistor on each output must be taken into account. The total differential gain calculation, assuming two baluns, is: PIN = PIN(MEAS) - PLOSS(BALUN AT 135MHz) POUT = POUT(MEAS) + PLOSS(BALUN AT 15MHz) + PLOSS(LOAD) where: 100 PLOSS(LOAD) = 20log = 32.3dB 4100 Power_Gain = POUT - PIN 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 evaluated at VGC = 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 spectrum analyzer. At 15.42MHz, losses due to the Anzac balun are approximately 0.3dB. For gain calculation, the attenuation due to the 2k load resistor on each output must be taken into account. The total differential gain calculation, assuming two baluns, is: PIN = PIN(MEAS) - PLOSS(BALUN AT 15MHz) POUT = POUT(MEAS) + PLOSS(BALUN AT 15MHz) + PLOSS(LOAD) where: 100 PLOSS(LOAD) = 20log = 32.3dB 4100 Voltage_Gain=POUT - PIN - 6dB The measured voltage gain at VGC = 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.
Evaluates: MAX2740
Adjustments and Control
The MAX2740 EV kit is configured with a 100k trim pot for setting and adjusting the VGA gain. To use an external 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 additional information.)
LNA
The LNA is a two-stage amplifier using feedback to set the gain. The circuit requires input and output matching. 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 differential pair. The second RF input is brought out to a separate pin for external decoupling on pin 7. The IF output is delivered through low-output-impedance emitter followers. 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-impedance, differential, 3-pole lowpass filter made up of discrete components.
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3
MAX2740 Evaluation Kit Evaluates: MAX2740
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 application, 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 digitizer 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 frequency 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.
4
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MAX2740 Evaluation Kit Evaluates: MAX2740
+3VA JU9 +3VA J1 + C1 10F JU1 L1 220nH L2 220nH +3VA_VCO C10 1000pF +3VA_AN C2 1000pF C4 0.015F C5 100pF L8 8.2nH C40 2.7pF C41 OPEN J22 SMA L12 0 C12 OPEN L11 0 C45 OPEN J21 SMA +3VA JU8 RFMIX_OUT+ J20 J19 RFMIX_OUTSMA SMA C35 1000pF C46 OPEN C47 OPEN C33 1000pF C32 1000pF
VCC
C39 100pF
IFMIX_OUT+ J18 J17 IFMIX_OUTSMA SMA
J2
GND
JU2
C37 1000pF R12 1.1k
C38 1000pF R11 1.1k 43 IFRMIXN_OUT
R3 100
C43 1000pF
38 IFMIXN_IN
39 IFMIX_IN
L9 8.2nH
44 FRMIX_OUT
LNA_OUT +3VA
C42 3pF
48
47
46
45
42
41
40
VCCIF_MIX
GND
LNA_OUT
GND
GND
VCCRF_MIX
IFRMIX_OUT-
FRMIX_OUT+
GNDIF_MIX
FRMIX_IN+
IFMIX_IN+
IFMIX_IN-
37
1
GND_2LNA
IFMIX_OUT+ IFMIX_OUTVGA_IN+ VGA_INGND
36 35 34 33 32 31 30 29 28 27 26 25
C31 0.015F C30 0.015F C29 0.015F
R13 2k
J16 SMA IFMIX_OUT+ J15 IFMIX_OUTSMA J14 VGA_IN+ SMA J13 VGA_INSMA
2 GND_2LNA LNA_IN J3 SMA L3 NO_LOAD C6 7pF 3 4 5 6 +3VA JU4 R2 100k JU3 C8 0.015F C7 100pF +3V_AN 9 10 11 +3V_VCO VCC_ANA GND_ANA GND 7 8 LNA_IN GND_1LNA GND_1LNA GND_AMIX FRMIX_INAGCON
R14 2k
C28 0.015F C27 0.015F R15 2k
U1 MAX2740
VGA_OUT+ VGA_OUTGND FGA_IN+ FGA_INGND FGA_OUT+ REF_IN
J12 VGA_OUT+ SMA J11 VGA_OUTSMA
C26 0.015F C25 0.015F
R16 2k
J10 SMA FGA_IN+ J9 FGA_INSMA
C24 0.015F R17 2k C23 0.015F
12 VCC_VCO GND_VCO GND_VCO GLS_OUT GND_DIG DOWN GND_DIG VCC_DIG
J8 SMA FGA_OUT+
13
14
15
16
17
18
UP
19
20
21
22
23
R20 15k C13 100pF D1 SIEMENS BBY 51-03W C3 12pF C44 2pF J4 SMA
L10 1.8nH C20 1000pF R19 453 J5 SMA GLS_OUT J6 SMA REF_IN C21 1000pF
FGAN_OUT 24
FGA_OUTC22 0.015F R18 2k J7 SMA FGA_OUT_
TANK
C9 OPEN
C16 0.015F C17 100pF L5 220nH JU7
TANK
+3VA R9 2.74k R4 100 +3VA 5 MAX4122 R5 12.1k U2 R8 12.1k C18 1000pF R6 2.74k C15 100pF R7 2.74k C19 100pF R10 2.74k
24
+3 -
C14 1000pF
Figure 1. MAX2740 EV Kit Schematic
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GND
5
MAX2740 Evaluation Kit Evaluates: MAX2740
1.0"
1.0"
Figure 2. MAX2740 EV Kit PC Board Layout--Component Side
Figure 3. MAX2740 EV Kit PC Board Layout--Ground Plane
1.0"
Figure 4. MAX2740 EV Kit PC Board Layout--Power Plane 6 _______________________________________________________________________________________
MAX2740 Evaluation Kit Evaluates: MAX2740
NOTES
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7
MAX2740 Evaluation Kit Evaluates: MAX2740
NOTES
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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