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19-1715; Rev 0; 4/00
MAX2720/MAX2721 Evaluation Kits
General Description
The MAX2720/MAX2721 evaluation kits (EV kits) simplify evaluation of the MAX2720/MAX2721 direct I/Q modulator with variable gain amplifier (VGA) and power amplifier (PA) driver. The MAX2720 is optimized for RF frequencies between 1700MHz and 2100MHz, while the MAX2721 is optimized for RF frequencies between 2100MHz and 2500MHz. The EV kits are fully assembled and tested, allowing simple evaluation of all device functions. All signal ports utilize SMA connectors, providing a convenient interface to RF test equipment. o Easy MAX2720/MAX2721 Evaluation o All Critical Peripheral Components Included o SMA Input and Output Signal Connectors o RF Ports Matched to 1900MHz (MAX2720) o RF Ports Matched to 2315MHz (MAX2721) o Fully Assembled and Tested
Features
Evaluate: MAX2720/MAX2721
Ordering Information
PART MAX2720EVKIT MAX2721EVKIT TEMP. RANGE -40C to +85C -40C to +85C IC PACKAGE 20 TSSOP-EP* 20 TSSOP-EP*
*Exposed paddle
Components Common to MAX2720/MAX2721
DESIGNATION C1, C4, C8, C9, C14, C17 C2 C3, C10, C13 C6, C7, C15, C16, C22, C23, C24 C11 C18 C19 C20, C21 L1 L2 R1, R3 R2 QTY 6 1 3 DESCRIPTION 470pF 10% ceramic caps (0402) Murata GRM36X7R471K050A 2pF 0.25pF ceramic cap (0402) Murata GRM36COG020C050A 1000pF 10% ceramic caps (0402) Murata GRM36X7R102K050A 0.1F 10% ceramic caps (0603) Murata GRM39X7R104K016A 3.0pF 0.25pF ceramic cap (0402) Murata GRM36COG030C050A 47pF 5% ceramic cap (0402) Murata GRM36COG470J050A 10F 10% tantalum capacitor AVX TAJC106K010 Not installed Not installed 3.9nH 5% inductor Toko LL1608-FS3N9J 100k resistors (0402) 10k resistor (0402) None 1 MAX2720/MAX2721 data sheet DESIGNATION R4 R5, R7, R9, R11 R6, R8, R10, R45 J1, J3, J4, J5, J7, J8 J2, J6 J10, J11, J12 JU2 JU4, JU5 JU6 None None None QTY 1 4 4 6 0 3 0 2 1 3 1 1 DESCRIPTION 20k potentiometer Bournes Digi-Key 3296W-203-ND 1.00k 1% resistors (0603) 49.9 1% resistors (0603) SMA edge-mount connectors EFJohnson 142-0701-801 Not installed Test points Not installed 1x3-pin headers (0.1in center) 1x2-pin header (0.1in center) Shunts (JU4, JU5, JU6) MAX2720/MAX2721 PC board MAX2720/MAX2721 EV kit data sheet
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________________________________________________________________ Maxim Integrated Products
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MAX2720/MAX2721 Evaluation Kits Evaluate: MAX2720/MAX2721
MAX2720 EV Kit Specific Components
DESIGNATION QTY C5 C12 L3 L4 U1 1 1 1 1 1 DESCRIPTION 8.0pF 0.5pF ceramic cap (0402) Murata GRM36COG080D050A 0 resistor (0402) 1.5nH 5% inductor Toko LL1608-FS1N5J 1pF 0.25pF ceramic cap (0402) Murata GRM36COG010C050A MAX2720EUP, 20-pin TSSOP-EP U1 1 DESIGNATION QTY C5 C12 L3 L4 1 1 1 1
MAX2721 EV Kit Specific Components
DESCRIPTION 6.0pF 0.5pF ceramic cap (0402) Murata GRM36COG060D050A 27pF 5% ceramic cap (0402) Murata GRM36COG270J050A 1.2nH 5% inductor Toko LL 1608-FS1N2J 3.3nH 5% inductor Toko LL1608-FS3N3J MAX2721EUP, 20-pin TSSOP-EP
Component Suppliers
SUPPLIER AVX EFJohnson Murata Toko PHONE FAX WEB www.avxcorp. com www.efjohnson. com www.murata. com www.tokoam. com 843-448-9411 843-448-1943 402-474-4800 402-474-4858 800-831-9172 814-238-0490 800-pik-toko 708-699-1194
* (Optional) A second power supply for varying the gain of the modulator
I/Q Modulator Connections and Setup
1) DC Power Supply: Set the power-supply voltage to +3V, and connect it to VCC and GND on the EV kit. If desired, place an ammeter in series with the power supply to measure supply current and a voltmeter in parallel with VCC and GND to measure the supply voltage delivered to the EV kit. Short jumper JU4 to VCC to enable the device. Short jumper JU6 to allow the potentiometer to vary the modulator gain; turn the potentiometer until V PC = 2.5V. If desired, open jumper JU6 and connect to an additional voltage supply to control the modulator gain. 2) LO Signal Source: The MAX2720/MAX2721 LO port can be driven at full or half frequency. Connect jumper JU5 (X2 ENB) to GND to enable the internal LO frequency doubler, allowing the external LO signal source to operate at half frequency. Set the LO signal source operating frequency to 950MHz (MAX2720) or 1157.5MHz (MAX2721) at an output power of -13dBm. Connect jumper JU5 (X2 ENB) to VCC to disable the internal LO frequency doubler, and run the external LO source at the fundamental frequency. Set the LO signal source frequency to 1900MHz (MAX2720) or 2315MHz (MAX2721) at an output power of -13dBm. Connect the LO signal generator to the LO port SMA connector using a 50 SMA cable. 3) I/Q Signal Source: Configure the dual-output function generator for a 500kHz IF frequency, with a 300mVp-p amplitude and a 90 phase difference between channels. Connect a 50 cable from the I/Q signal source to the EV kit's I+ and Q+ inputs. The EV kit inputs are terminated with a 50 resistor shunted to ground and a 1k resistor in series with
Quick Start
Test Equipment Required
* One low-noise RF-signal generator (50 source) capable of delivering at least -10dBm of output power over 1.7GHz to 2.5GHz (HP 8648C, for example) * One I/Q generator capable of producing two 500kHz sine waves, 90 out of phase with each other, with an amplitude of 300mVp-p (HP 8904A with option 2, for example) * One dual-channel oscilloscope with a 100MHz minimum bandwidth * Two low-capacitance (<3.0pF) oscilloscope probes (Tektronix P6201, for example) * One spectrum analyzer capable of covering the MAX2720/MAX2721 RF frequency range of the HP 8561E, for example * Two 50 BNC-to-SMA cables * Two 50 SMA cables * One power supply capable of providing a minimum of 150mA of supply current at +3V * (Optional) Digital multimeters (DMMs) to monitor DC supply voltage and supply current
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VCC VCC 3 C23 0.1F 2 PC J11 1 1 JU2 1 R4 20k 2 2 JU6 C24 0.1F JU4 3 SHDN JU5 3 X2_ENB
VCC
VCC
VCC
J10
J12
C19 C22 10F 0.1F
J1 VCC L2 3.9nH 1 GND DRIN GND PC MODOUT 17 16 15 14 13 12 11 C15 0.1F C21 OPEN R9 1k C14 470pF VCC X2_ENB L3 1.5nH (1.2nH*) 18 19 C10 1000pF DROUT SHDN VCC GND ENX2 VCC QQ+ VCC LO VCC II+ VCC GND 20 2 3 4 5 6 7 C6 0.1F 8 VCC 9 10 R2 10k C11 3.0pF L1 OPEN J4 SMA
C1 470pF
Figure 1. MAX2720/MAX2721 EV Kits Schematic
C2 2.0pF C3 1000pF PC J5 SMA L4 C12 1pF (3.3nH*) 0 (27pF*)
SMA
SHDN
R1 VCC 100k
VCC
U1 MAX2720 MAX2721
C4 470pF R3 100k VCC C13 C9 1000pF 470pF
J6 SMA R8 49.9 R10 49.9 J7 SMA
C5 8pF (5pF*)
J2
R5 1k
SMA C8 470pF
R45 49.9 C16 0.1F C18 47pF
C20 OPEN
J3
R7 1k
R11 1k
VCC
SMA
C17 470pF
R6 49.9
C7 0.1F
J8
SMA
Evaluate: MAX2720/MAX2721
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*COMPONENT VALUES ARE FOR MAX2721 ONLY.
MAX2720/MAX2721 Evaluation Kits
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MAX2720/MAX2721 Evaluation Kits Evaluate: MAX2720/MAX2721
the baseband input of the MAX2720/MAX2721, which has a 2k (typ) input impedance. This voltage divider results in a 200mVp-p signal applied to the MAX2720/MAX2721s' I+ and Q+ inputs. Use the oscilloscope and its two probes to verify that the amplitude difference between the two signals at the I and Q inputs is at a minimum and the phase difference is 90. 4) Spectrum Analyzer: Connect the spectrum analyzer to the MODOUT SMA connector using a 50 SMA cable. Set the spectrum analyzer's center frequency to 1900MHz (MAX2720) or 2315MHz (MAX2721). Set the spectrum analyzer's reference level to 0dBm and the span to 1.2MHz. power supply to measure supply current and a voltmeter in parallel with the VCC and GND connections to measure the supply voltage delivered to the EV kit. Short jumper JU4 to VCC to enable the device. 2) Spectrum Analyzer: Connect the spectrum analyzer to the DROUT SMA connector using a 50 SMA cable. Set the spectrum analyzer's center frequency to 1900MHz (MAX2720) or 2315MHz (MAX2721). Set the spectrum analyzer's reference level to 10dBm and the span to 1MHz. 3) RF Signal Source: Set the signal generator to an output power of -12dBm at a frequency of 1900MHz (MAX2720) or 2315MHz (MAX2721). Connect the signal generator to the DRIN SMA connector using a 50 SMA cable.
I/Q Modulator Analysis
Turn on the power supply and the LO and I/Q signal generators. The ammeter should read approximately 77mA (MAX2720) or 86mA (MAX2721) with the LO doubler enabled, or 72mA (MAX2720) or 81mA (MAX2721) with the LO doubler disabled. Using the spectrum analyzer, observe the modulator output spectrum. Notice three tones: the carrier, and the lower and upper sidebands 500kHz below and above the carrier. In its peak power setting (V PC = 2.5V), the desired sideband will have an amplitude of -8.5dBm (MAX2720) or -5.0dBm (MAX2721). The carrier suppression is typically 33dB (MAX2720) or 31dB (MAX2721), while the sideband suppression is typically 40dB (MAX2720) or 35dB (MAX2721). Phase and amplitude differences at the I and Q inputs result in degradation of the carrier and sideband suppression. Be sure to take into account board losses (0.3dB) when calculating the output power of the device.
PA Driver Analysis
Turn on the power supply and RF signal generator. The spectrum analyzer should measure an output power of +1.5dBm (13.5dB gain) for the MAX2720 or -0.5dBm (11.5dB gain) for the MAX2721. Be sure to take into account board losses (0.3dB at the input, 0.3dB at the output) when calculating the output power of the device.
Layout and Bypassing
Good PC board layout is an essential aspect of RF circuit design. The MAX2720/MAX2721 EV board can serve as a guide for layout of your board. Make sure the input traces to the I and Q input pins are of equal length and in the same environment as much as possible to keep the I and Q signals in quadrature for maximum sideband rejection at the modulated output. Keep PC board trace lengths as short as possible to minimize parasitics and losses. Keep bypass capacitors as close to the device as possible with low-inductance connections to the ground plane.
PA Driver Connections and Setup
1) DC Power Supply: Set the power-supply voltage to +3V, and connect it to VCC and GND on the EV kit. If desired, place an ammeter in series with the
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MAX2720/MAX2721 Evaluation Kits Evaluate: MAX2720/MAX2721
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Figure 2. MAX2720/MAX2721 EV Kits PC Board Layout-- Component Placement Guide
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Figure 3. MAX2720/MAX2721 EV Kits PC Board Layout-- Component Side (Layer 1, Top)
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Figure 4. MAX2720/MAX2721 EV Kits PC Board Layout-- Ground Plane (Layer 2)
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MAX2720/MAX2721 Evaluation Kits Evaluate: MAX2720/MAX2721
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Figure 5. MAX2720/MAX2721 EV Kits PC Board Layout-- Power Plane (Layer 3)
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Figure 6. MAX2720/MAX2721 EV Kits PC Board Layout-- Power Plane (Layer 4, Bottom)
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.
6 _____________________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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