QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1233A-X 1.5GHZ TO 3.8GHZ HIGH LINEARITY UPCONVERTING MIXER LT5579 DESCRIPTION Demonstration circuit 1233A-x is a high linearity up- The DC1233A-x series of demonstration circuits are converting mixer featuring the LT5579. designed for evaluating the LT5579 IC at several com- mon frequency ranges: The LT 5579 is a high performance upconverting mixer IC optimized for output frequencies in the 1.5GHz to VERSION APPLICATION IF INPUT LO INPUT RF OUTPUT 3.8GHz range. It features single-ended LO input and RF -A WiMAX 456MHz Low-side 3.6GHz output ports to simplify board layout and to reduce sys- -B WiMAX 456MHz High-side 2.6GHz tem cost. -C UMTS 240MHz High-side 2.14GHz -D PCS 240MHz Low-side 1.95GHz The LT5579 offers a superior alternative to passive mix- ers. Unlike passive mixers which have conversion loss and require high LO drive levels, the LT5579 delivers Demonstration circuit 1233A-x can be easily optimized conversion gain at significantly lower LO input levels for operations at other frequencies. Refer to the Appli- and is less sensitive to LO power level variations. Only cation Note section and the LT5579 data sheet for de- -1dBm of LO power is needed, and the balanced design tails. results in low LO signal leakage to the RF output. The Design files for this circuit board are available. Call lower LO drive level requirements, combined with the the LTC factory. excellent LO leakage performance, translate into lower , LT, LTC, and LTM are registered trademarks of Linear Technology Corp. LO signal contamination of the output signal. All other trademarks are the property of their respective owners. Table 1. Typical Demo Circuit Performance Summary (T = 25C, V = 3.3V, P = -5dBm (-5dBm/tone for 2-tone tests, f = 1MHz), A CC IF P = -1dBm, unless otherwise noted. Low side LO for 1950MHz and 3600MHz. High side LO for 2140MHz and 2600MHz.) LO PARAMETER CONDITIONS TYPICAL PERFORMANCE Supply Voltage 3.3V Supply Current 226mA LO Input Frequency Range 1.1GHz to 4GHz LO Input Power -5 to +2dBm 1233A-A 1233A-B 1233A-C 1233A-D WiMAX 3.6GHz WiMAX 2.6GHz UMTS PCS IF Input Frequency Range 12dB Return Loss, LO applied 330 to 505MHz 330 to 505MHz 174 to 263MHz 174 to 263MHz RF Output Frequency Range 10dB Return Loss, LO applied 3170 to 4100MHz 2260 to 2780MHz 2035 to 2285MHz 1840 to 2020MHz Conversion Gain -0.5dB 1.3dB 2.6dB 1.9dB Conversion Gain vs. Temperature T = -40C to 85C -0.027dB/C -0.027dB/C -0.020dB/C -0.020dB/C A Output 3rd Order Intercept 23.2dBm 26.2dBm 27.3dBm 28dBm Output 2nd Order Intercept 54dBm 45dBm 42dBm 40dBm Single Sideband Noise Figure 12dB 12dB 9.9dB 9.9dB Output Noise Floor P = -5dBm -155.5dBm/Hz -157.5dBm/Hz -158.1dBm/Hz -158.1dBm/Hz OUT Output 1dB Compression 10.7dBm 13.7dBm 13.9dBm 13.6dBm IF to LO Isolation 73dB 74dB 81dB 80dB LO to IF Leakage -22dBm -26dBm -28dBm -25dBm LO to RF Leakage -35dBm -36dBm -35dBm -34dBm 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1233A-X 1.5GHZ TO 3.8GHZ HIGH LINEARITY UPCONVERTING MIXER APPLICATION NOTE 3. The 70 microstrip transmission line TL1 and TL2 ABSOLUTE MAXIMUM RATINGS provide inductances required for matching. At lower Supply Voltage......................................................3.6V frequencies, external inductors are necessary. LO Input Power.............................................. +10dBm 4. R1 and R2 set the DC current in the mixer core to the LO Input DC Voltage .................... -0.3V to V + 0.3V CC optimum level of 50mA per side. Their values should RF Output DC Current........................................ 60mA be well matched for best LO leakage performance. IF Input Power (Differential).......................... +13dBm 0.1% tolerance is recommended. + - IF , IF DC Currents ........................................... 60mA T .................................................................150C 5. L1 and L2 reduce the loading effect of R1 and R2. JMAX Operating Temperature Range.............. -40C to 85C Their self-resonant frequency should be at least sev- Storage Temperature Range............... -65C to 150C eral times the IF frequency. High quality wire-wound type inductors are recommended. The DC resis- tances of L1 and L2 need to be accounted for in the IF INPUT INTERFACE selection of R1 and R2. The standard demonstration circuit 1233A-x can be re- configured for other IF input frequencies. The details of LO INPUT INTERFACE the matching circuit are omitted in this guide, since the LT5579 datasheet presents in depth explanations and The LT5579s LO input port is internally matched from the ICs IF input differential impedance. Matching com- 1.1GHz to 4GHz, with a minimum return loss across ponent values for several common IF input frequencies this range of about 9dB at 2.3GHz. External matching are listed in Table 2. Refer to the demonstration circuit should be used for lower LO frequencies for best per- schematic in Figure 3. formance. Refer to the LT5579 datasheet for more in- formation and impedance data. Table 2. IF Input Component Values R1,R2 IF Freq. C1,C2 C9 (1) C3 TL1,TL2 L1,L2 RF OUTPUT INTERFACE (MHz) (pF) (pF) (pF) (3) (nH) () The LT5579 utilizes an internal RF transformer to step 70 1000 120 (2) 4.7nH 100 9.1 down the mixer core output impedance to simply RF output matching. Matching component values for sev- Z =70 140 1000 120 (2) 100 9.1 0 eral common RF output frequencies are listed in Table Z =70 240 82 33 (2) 40 11 0 3. High quality precision microwave capacitors, such 450 33 33 (2) Z =70 40 11 as the AVX Accu-p series, should be used for C8 to 0 minimize parasitics. NOTE: 1. Center of C9 is 3mm from the edge of the IC package Table 3. RF Output Component Values for all cases. RF Frequency (MHz) C8 (pF) L3 (nH) 2. C3 is a small-valued capacitor used to improve the 1650 1.5 6.8 LO-RF leakage in some applications, and it has little 1750 1.2 6.8 effect on impedance matching. C3s value and loca- 1950 1 4.7 tion depend on LO and RF frequencies and are de- 2140 termined experimentally. In certain instances, two 0.45 3.9 common-mode capacitors to ground instead of one 2600 - 1.0 single differential capacitor may provide better leak- 3600 0.7 0 age suppression. 2