QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1027A LOW POWER ACTIVE MIXER LT5560 DESCRIPTION Demonstration circuit 1027A is optimized for down- which allow the LT 5560 to be used as an up- or converting mixer tests & measurements for input down-conversion mixer in a wide variety of frequency range of 79MHz to 300MHz and an output applications. frequency range of 3MHz to 67MHz, (for 12dB return loss). The LO port frequency range is 176MHz to The LT 5560 is characterized with a supply current of 316MHz (10dB return loss). Demo circuit 1027A can 10mA however, the DC current is adjustable, which also be optimized for HF, VHF up-converting allows the performance to be optimized for each applications. application by changing the value of resistor R1. For The LT 5560 is a 0.01MHz to 4000MHz low power, Icc=10mA the value of R1=3 Ohm. Operation at a high performance broadband Up/Down-converting lower supply current will, however, degrade linearity. active mixer. This double-balanced mixer can be Design files for this circuit board are available. Call driven by a single-ended LO source and requires 2dBm of LO power. The signal ports can be the LTC factory. LT is a registered trademark of Linear Technology Corporation. impedance matched to a broad range of frequencies, Table 1. Typical Performance Summary (T = 25C) A PARAMETER CONDITION (f = 250MHz, f =260MHz) 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 2.7dB INPUT LO SSB Noise Figure P = -2dBm 8.8dB LO rd Input 3 Order Intercept 2-Tone, -20dBm/Tone, delta f = 1MHz, P = -2dBm +9.6dBm LO nd Input 2 Order Intercept +46dBm 2-Tone, -20dBm/Tone, delta f = 1MHz, P = -2dBm LO Input 1dB Compression P = -2dBm 0.4dBm LO LO to IN leakage P = -2dBm -63dBm LO LO to OUT leakage P = -2dBm -44dBm LO 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1027A LOW POWER ACTIVE MIXER QUICK START PROCEDURE rd 6. To measure 3 order distortion and conversion Demonstration circuit 1027A is easy to set up to gain, set the Spectrum Analyzer start and stop evaluate the performance of the LT 5560. Refer to frequencies to 7MHz and 12MHz, respectively. Figure 1 for proper measurement equipment setup Sufficient spectrum analyzer input attenuation and follow the procedure below: should be used to avoid distortions in the NOTE: instrument. a. Use high performance signal generators with rd 7. The 3 order intercept point is equal to (P P ) / low harmonic output. Otherwise, low-pass 1 3 2 + P , where P is the power level of the two filters at the signal generator outputs should be in 1 nd fundamental output tones, at 9MHz and 10MHz, used to suppress harmonics, particularly the 2 rd P is the 3 order distortion products at 8MHz or harmonic. 3 11MHz, and P is the input power (in this case in b. High quality combiners that provide a 50 Ohm minus 20dBm). All units are in dBm. termination on all ports and have good port-to- 8. Using the same signal generator settings, output port isolation should be used. Attenuators on IM2 product can be measured at 1MHz, which is a the outputs of the signal generators are difference between two input frequencies recommended to further improve source (250MHz and 251MHz). However we recommend isolation and to reduce reflection into the increasing the frequency of the second signal sources. generator from 251MHz to 253MHz and measure 1. Connect all test equipment as shown in Figure 1. the output IM2 product at 3MHz frequency 2. Set the DC power supplys current limit to 15mA, (253MHz-250MHz=3MHz). At 3MHz the mixer and adjust output voltage to 3V. output matching circuit has good return loss. To nd measure input 2 order distortion, set the 3. Connect Vcc to the 3V DC supply, and then Spectrum Analyzer center frequency to 3MHz. connect EN to 3V the Mixer is enabled (on). nd 9. The 2 order intercept point is equal to P P + 1 2 4. Set Signal Generator 1 to provide a 260MHz, P , where P is the power level of the fundamental in 1 -2dBm, CW signal to the demo board LO input nd output tone at 7MHz, P is the 2 order product at 2 port. 3MHz, and P is the input power (in this case in 5. Set the Signal Generators 2 and 3 to provide minus 20dBm). two -20dBm CW signals to the demo board RF input portone at 250MHz, and the other at 251MHz. 2