QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC991A LOW POWER ACTIVE DOWN-CONVERTING MIXER LT5560 DESCRIPTION Demonstration circuit DC991A is optimized for a an up- or down-conversion mixer in a wide variety of down-converting mixer tests & measurements for applications. input frequency range of 700MHz to 1680MHz, an output frequency range of 110 MHz to 170MHz (12 The LT 5560 is characterized with a supply current of dB return loss BW). The LO port frequency range is 10mA however, the DC current is adjustable, which 515 to 915MHz (10 dB return loss BW). allows the performance to be optimized for each application by changing the value of resistor R1. For The LT 5560 is a high performance broadband Icc=10mA the value of R1=3-ohm. Operation at a Up/Down-converting active mixer. This double- lower supply current will, however, degrade linearity. balanced mixer can be driven by a single-ended LO source and requires 2dBm of LO power. The signal Design files for this circuit board are available. Call ports can be impedance matched to a broad range of the LTC factory. frequencies, which allow the LT 5560 to be used as LT is a registered trademark of Linear Technology Corporation. Table 1. Typical Performance Summary (T = 25C) A PARAMETER CONDITION (f = 900MHz, f =760MHz) VALUE INPUT LO Supply Voltage 2.7V to 5.3V Supply Current V = 3V, EN = High, R1=3 10mA CC Maximum Shutdown Current V = 3V, EN = 0.3V 10A CC Signal Input Frequency Range Requires External Matching < 4000 MHz LO Signal Frequency Range Requires External Matching < 4000 MHz Signal Output Frequency Range Requires External Matching < 4000 MHz IF Input Return Loss Z = 50, with External Matching 15dB 0 LO Input Return Loss Z = 50, with External Matching 15dB 0 RF Output Return Loss Z = 50, with External Matching 15dB 0 LO Input Power -6dBm to 1dBm Conversion Gain P = -20dBm, P = -2dBm 2.6dB INPUT LO P = -2dBm SSB Noise Figure 10.1dB LO rd Input 3 Order Intercept 2-Tone, -20dBm/Tone, Df = 1MHz, P = -2dBm +9.7dBm LO nd Input 2 Order Intercept 2-Tone, -20dBm/Tone, Df = 1MHz, P = -2dBm +47dBm LO Input 1dB Compression P = -2dBm 0dBm LO LO to IN leakage P = -2dBm -57dBm LO LO to OUT leakage P = -2dBm -63dBm LO 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC991A LOW POWER ACTIVE DOWN-CONVERTING MIXER QUICK START PROCEDURE Demonstration circuit DC991A is easy to set up to input portone at 900MHz, and the other at evaluate the performance of the LT 5560. Refer to 901MHz. Figure 1 for proper measurement equipment setup rd 6. To measure 3 order distortion and conversion and follow the procedure below: gain, set the Spectrum Analyzer start and stop NOTE: frequencies to 138MHz and 143MHz, respectively. Sufficient spectrum analyzer input attenuation a. Use high performance signal generators with nd rd should be used to avoid distortion in the low harmonic output for 2 & 3 order instrument. distortion measurements. Otherwise, low-pass rd filters at the signal generator outputs should be 7. The 3 order intercept point is equal to (P P ) / 1 3 nd used to suppress harmonics, particularly the 2 2 + P , where P is the power level of the two in 1 harmonic. fundamental output tones at 140MHz and rd 141MHz, P is the 3 order product at 139MHz 3 b. High quality combiners that provide a 50 Ohm and 142MHz, and P is the input power (in this in termination on all ports and have good port-to- case, -20dBm). All units are in dBm. port isolation should be used. Attenuators on the outputs of the signal generators are 8. Using the same signal generators settings, output recommended to further improve source IM2 product can be measured at 1MHz, which is a isolation and to reduce reflection into the difference between two input frequencies (900 sources. and 901MHz). However we recommend increasing the frequency of the second signal 1. Connect all test equipment as shown in Figure 1. generator from 901MHz to 1045MHz and measure 2. Set the DC power supplys current limit to 15mA, OIM2 product at 145MHz frequency (1045MHz- and adjust output voltage to 3V. 900MHz=145MHz). At 145MHz the mixer output matching circuit has good return loss. To measure 3. Connect Vcc to the 3V DC supply, and then nd input 2 order distortion, set the Spectrum connect EN to 3V the Mixer is enabled (on). Analyzer center frequency to 145MHz. 4. Set Signal Generator 1 to provide a 760MHz, nd 9. The 2 order intercept point is equal to P P + 1 2 -2dBm, CW signal to the demo board LO input P , where P is the power level of the fundamental in 1 port. nd output tone at 140MHz, P is the 2 order product 2 5. Set the Signal Generators 2 and 3 to provide at 145MHz, and P is the input power (in this case in two -20dBm CW signals to the demo board RF -20dBm). 2