Abstract: The MAX2682 miniature, low-cost, low-noise downconverter is designed for low-voltage operation and is ideal for use in portable communications equipment. Signals at the RF input port are mixed with signals at the local oscillator (LO) port using a double-balanced mixer. This downconverter operates with RF input frequencies between 400MHz and 2500MHz, and downconverts to IF output frequencies between 10MHz and 500MHz Additional Information: Wireless Product Line Page MAX2680/MAX2681/MAX2682 The MAX2140 Complete SDARS Receiver The MAX2472/MAX2473 500MHz to 2500MHz VCO Buffer Amplifiers Applications Technical Support This application note presents measured performance for the MAX2682 low noise downconverter when it is tuned for a satellite receiver system. The radio frequency (RF) is 2642.5MHz, and the intermediate frequency (IF) is 402.5MHz. High side injection is used, placing the local oscillator (LO) at 3.045GHz. Return loss for each port is given, along with a table of gain and noise figure. With – 5dBm LO drive level, the gain is 6.56dB and the noise figure is 13.3dB. MAX2682 Description The MAX2682 is a miniature, low-cost, low-noise downconverter designed for low-voltage operation and is ideal for use in portable communications equipment. Signals at the RF input port are mixed with signals at the LO port using a double-balanced mixer. This downconverter operates with RF input frequencies between 400MHz and 2500MHz, and downconverts to IF output frequencies between 10MHz and 500MHz. The MAX2682 downconverter operates from a single +2.7V to +5.5V supply, ideal for hand held applications. Each downconverter features a low-power shutdown mode in which it typically draws less than 0.1µA of supply current. The MAX2682 downconverter is manufactured on a high-frequency, low-noise, advanced silicon-germanium process and is offered in the space-saving 6-pin SOT23 package. Figure 1. Typical operating circuit (the values of matching components C2, L1, R1, Z1, Z2, and Z3 depend on the IF and RF frequency and downconverter). The MAX2682 mixer has been retuned for the following parameters: 1. RF = 2642.5MHz 2. IF = 402.5MHz 3. LO frequency = 3045MHz 4. BW (bandwidth) = 25MHz 5. Vcc = 3.3V Figure 2 shows the matching networks used to make all measurements in this report. Figure 2. Matching network for 2642.5MHz satellite radio. Measured Performance Figure 3. LO port return loss. Figure 4. RF port return loss. Figure 5. IF port return loss. Figure 6. Return loss measurement set up. Figure 7 shows very flat gain, down only 0.2dB at 12.5MHz band edge. Figure 7. Gain flatness. Isolation LO – IF = 10.67dB LO – RF = 16.67dB Below is the raw data taken for the isolation measurement. LO IF Isolation -5dBm -15.67dBm 10.67dB       LO RF Isolation -5dBm -21.67dBm 16.67dB Figure 8. Test set up used for isolation measurement. Table 1 below contains the noise figure data for the MAX2682 versus LO power level. Table 1. Noise Figure Data LO Power (dBm) Gain (dB) NF (dB) 0 7.3 11.86 -1 7.26 12.1 -2 7.17 12.36 -3 7.05 12.64 -4 6.86 12.97 -5 6.56 13.3 -6 6.2 13.73 Figure 9. Noise figure test set up. The signal generator used to provide the LO (3.045GHz) is the HP8638C. 相关型号   APP 1826: Jan 09, 2003 MAX2682 400MHz至2.5GHz、低噪声、SiGe下变频混频器 完整的数据资料 (PDF, 200kB) 免费样品 自动更新 需要自动接收最新发布的应用笔记吗？请订阅EE-Mail™ (English only)。 我们期待您的反馈！ 喜欢？不喜欢？有待改善？或为我们提供建议？请与我们联系 — 我们将根据您的意见或建议改善我们的工作。 网页评价或提供建议   下载，PDF格式 (76kB)  AN1826, AN 1826, APP1826, Appnote1826, Appnote 1826