DC2091A Analog Devices

DEMO MANUAL DC2091A LTC5599 30MHz to 1300MHz Low Power Direct Quadrature Modulator Description Demonstration circuit 2091A is optimized for evaluation gain, and allows optimization of the LO carrier feedthrough of the LTC 5599 low power direct quadrature modulator. and side-band suppression. The balanced I and Q baseband input ports can be either Design files for this circuit board are available at AC- or DC-coupled to a source with a common mode volt- DEMO MANUAL DC2091A a Maxi Mu M i r Supply Voltage .........................................................3.8V Case Operating Temperature Range ....... 40C to 105C Common Mode Level of BBPI, BBMI, Storage Temperature Range .................. 65C to 150C and BBPQ, BBMQ ...................................................2V CAUTION: ThIS PART IS SeNSITIve TO ele CTRO- LOL, LOC DC Voltage ............................................. 0.1V STATIC DISChARge (eSD). ObSeRve PROPeR eSD LOL, LOC Input Power .........................................20dBm PReCAUTIONS whe N hANDl INg The l TC5599. Voltage on Any Pin ...........................0.3V to V + 0.3V CC T .................................................................... 150C JMAX n t e M D s Use high performance signal generators with fully Before taking measurements, the system performance configurable differential I and Q outputs, such as the should be evaluated to ensure that: Rohde & Schwarz SMJ100A vector signal generator or 1) clean input signals can be produced equivalent. 2) the spectrum analyzers internal distortion is mini- Use narrow resolution bandwidth (RBW) and engage mized video averaging on the spectrum analyzer to lower the 3) the spectrum analyzer has enough dynamic range displayed average noise level (DANL) in order to improve and sensitivity sensitivity and to increase dynamic range. The trade-off is increased sweep time. 4) the system is accurately calibrated for power and frequency. Spectrum analyzers can produce significant internal dis- tortion products if they are overdriven. Generally, spectrum Digital modulation often requires DC coupling and flat analyzers are designed to operate at their best with about frequency response. For best EVM performance with 30dBm to 40dBm at their input filter or preselector. complex modulation, the RC networks at the baseband Sufficient spectrum analyzer input attenuation should be I/Q inputs are not required. used to avoid saturating the instrument, but too much attenuation reduces sensitivity and dynamic range. q s p D 1. Remove the demonstration circuit from its protective 7. Verify the total V supply current is approximately CC packaging in an ESD-safe working area. 28mA. The demonstration circuit is now turned on and is ready for measurements. 2. Turn off the DC power supply as well as the baseband and LO signal sources outputs. 8. Turn on the output of the LO source and apply a 492.8MHz, 0dBm CW Signal. 3. Connect all test equipment as show in Figure 1. 9. Set the baseband signal source to provide a 100kHz, 4. Make sure jumper JP1 is installed and the jumper JP2 200mV baseband input signal. The I and Q P-P(DIFF) is installed at the 1-2 position. channels should be 90 shifted and set for lower 5. Slowly increase the supply voltage to 3.3V. Do not sideband selection. exceed 3.8V. 10. Measure the modulators RF output on the Spectrum 6. Turn on the baseband signal source. Set the baseband Analyzer at 492.7MHz. common mode bias to 1.4V. dc2091afa 2 ure roce tart uick etup an ent quip est on otes atings nput bsolute