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dc2391af

DEMO MANUAL DC2391A

NOTES ON TEST EQUIPMENT AND SETUP

QUICK START PROCEDURE

•  Use a high performance baseband signal genera-

tor with differential outputs, such as the Rohde & 

Schwarz SMJ100A vector signal generator or 

equivalent.

•  The LO harmonics can degrade image rejection 

severely. Third harmonic should be kept at least 6dB 

lower than the desired image rejection, or it should 

be compensated by adjusting the quadrature phase 

balance, register 0x05. In the extreme case of nearly 

square wave LO drive, large offset values may be 

required for registers 0x04 and 0x05.

•  Use narrow resolution bandwidth (RBW) and engage 

video averaging on the spectrum analyzer to lower 

the displayed average noise level (DANL). The trade-

off is increased sweep time.

•  Spectrum analyzers can produce significant internal 

distortion products if overdriven. Generally, spectrum 

analyzers are designed to operate their best with 

about –30 to –40dBm at their 1st mixer. Sufficient 

spectrum analyzer input attenuation should be used 

to avoid overdrive, but too much attenuation reduces 

sensitivity and dynamic range.

•  Before taking measurements, the system performance 

should be evaluated to ensure that: 1) clean baseband 

signals can be produced, 2) the LO harmonics and 

phase noise are minimized for CW LO drive, 3) the 

spectrum analyzer’s internal distortion is minimized, 

and noise floor is satisfactory.

1.  Remove the DC2391A from its protective packaging in 

an ESD-safe working area (see Figure 1). Make sure 

jumper JP1 is installed (V

CTRL

 = V

CC

).

2.  Set the baseband signal generator output DC common-

mode voltage to +1.4VDC, set the amplitude (V

emf

) = 1V 

diff, but do not yet connect the 4 cables to the DC2391A.

3.  Connect the DC power supply and increase voltage 

to +3.3V. Using a voltmeter, verify the voltage at the 

LTC5589 V

CC

 pin or JP1 is +3.3V. Adjust if necessary.

4. Apply 

3.3V to DC2391A’s enable input (EN).The enable 

voltage must never exceed the LTC5589’s V

CC

 supply 

voltage by 0.3V or drop below –0.3V.

5.  Verify the total V

CC

 supply current is approximately 

29mA. 

6.  Connect the RF output to the spectrum analyzer. 
7.  Connect the LO source to the LO input and apply a 

2560MHz, 0dBm CW LO signal.

8.  Configure the baseband signal source to provide a 

single CW carrier with 100kHz offset. I- and Q-channels 

should be in phase-quadrature and set for lower side-

band selection.

9.  Observe the modulator’s RF output on the spectrum 

analyzer at 2559.9MHz. Also observe the sideband 

suppression (aka Image Rejection) at 2560.1MHz, 

and the LO Leakage at 2560MHz.

10.  Up to this point, the I/Q Modulator has been at default 

center frequency and gain, with no trims. To change 

modulator center frequency, gain, etc., connect the 

Linduino to the DC2391A with the ribbon cable pro-

vided. Make sure jumper JP3 on the DC2026C is set 

to 3.3V.

11.  Run QuikEval

 to start the GUI associated with the I/Q 

modulator. 

12. Be sure to update the QuikEval to get latest software 

version that supports the LTC5589. LTC5589 GUI will 

automatically be installed on the computer for the 

first time when DC2391A is connected to Linduino 

DC2026C.

13. The turn off procedure is the reverse of the turn on 

procedure: Make sure V

EN

 is removed before V

CC

.

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Summary of Contents for DC2391A

Page 1: ...e can either be automatically triggered or entirely switched off L LT LTC LTM Linear Technology the Linear logo and Linduino are registered trademarks and QuikEval is a trademark of Linear Technology Corporation All other trademarks are the property of their respective owners Design files for this circuit board are available at http www linear com demo DC2391A Figure 1 Test Setup for RF Performanc...

Page 2: ...TRL VCC 2 SetthebasebandsignalgeneratoroutputDCcommon modevoltageto 1 4VDC settheamplitude Vemf 1V diff butdonotyetconnectthe4cablestotheDC2391A 3 Connect the DC power supply and increase voltage to 3 3V Using a voltmeter verify the voltage at the LTC5589 VCC pin or JP1 is 3 3V Adjust if necessary 4 Apply3 3VtoDC2391A senableinput EN Theenable voltage must never exceed the LTC5589 s VCC supply vol...

Page 3: ...fsets can be trimmed out as can SSB suppression via the controls on left side of form 6 In end applications Linduino C code is available to help user get from engineering units MHz dB gain mV dBanddegreesimbalance toregistervalues and vice versa 7 The LTC5589 registers reset to default while starting QuikEvalGUI whichdefaultsCLOENbit bit4 register 0x06 to 1 This allows for the automatic adjustment...

Page 4: ...OW SULLINS NRPN021PAEN RC 13 1 XJP5 SHUNT 2mm CTRS SAMTEC 2SN BK G 14 6 J1 J6 CONN SMA 50Ω EDGE LANCH E F JOHNSON 142 0701 851 15 0 J7 J8 CON OPT 16 1 L1 IND 4 7nH 0402HP COILCRAFT 0402HP 4N7XJLU 17 1 P1 HEADER 2X7PIN 0 079CC MOLEX 87831 1420 18 1 R1 RES CHIP 1 1 0402 VISHAY CRCW04021R00FKED 19 6 R7 R16 R17 R18 R19 R22 RES CHIP 1k 1 0402 VISHAY CRCW04021K00FKED 20 3 R13 R14 R15 RES CHIP 4 99k 1 04...

Page 5: ... 1 LOW POWER I Q MODULATOR 0 7GHz 3 8GHz AK ANDY M N A LTC5589IUF DEMO CIRCUIT 2391A SIZE DATE IC NO REV SHEET OF TITLE APPROVALS PCB DES APP ENG TECHNOLOGY Fax 408 434 0507 Milpitas CA 95035 Phone 408 432 1900 1630 McCarthy Blvd LTC Confidential For Customer Use Only CUSTOMER NOTICE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER SUPPLIED SPECIFICATIONS HOWEVER IT...

Page 6: ...RPOSE EXCEPT TO THE EXTENT OF THIS INDEMNITY NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES The user assumes all responsibility and liability for proper and safe handling of the goods Further the user releases LTC from all claims arising from the handling or use of the goods Due to the open construction of the product it is the user s respon...

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