[问答]

噪声系数测量问题

问答对人有帮助，内容完整，我也想知道答案 0 美好的一天，我有N9875A与N4002A。我需要测量上变频器NF，但RF频率为30 - 31 GHz。 IF为1 - 2 GHz。（LO = 29 GHz）现在我正在使用无源混频器混频到IF，即1 - 2 GHz。所以我选择了“放大器”测量。对于校准，我只是测量了损耗并将其添加到输出损耗参数中 - 在测量设置中。输出上没有过滤器或任何东西。噪声源直接连接到DUT输入。更具体：UUT的增益约为34 dB。混频器损耗约为10 dB。电缆损耗约为1 dB。 UUT的功率为~0dBm。我的值高于预期值 - 应该是~10-11 dB，我得到~13 - 15 dB。有什么我在这里俯瞰的吗？我应该以某种方式直接校准混频器（和电缆等）吗？我需要在调音台的输出上使用滤波器吗？我唯一能通过完整的1 - 2 GHz频段的滤波器是低通滤波器。我将不胜感激。布鲁斯以上来自于谷歌翻译以下为原文 Good day, I have N9875A with N4002A. I need to measure upconverter NF but the RF is at 30 - 31 GHz. IF is 1 - 2 GHz. (LO =29 GHz) Right now I am using a passive mixer to mix down to the IF, i.e. 1 - 2 GHz. So I have select "amplifier" measurement. For calibration, I have simply measured the loss and added that into the output loss parameter - in the measurement setup. No filters or anything on the output. Noise source is connected directly to the DUTs input. More specifics: Gain of UUT is about 34 dB. Loss of mixer is about 10 dB. Cable loss is about 1 dB. Power out of UUT is ~ 0dBm. I am getting higher than expected values - should be ~10-11 dB, I am getting ~13 - 15 dB. Is there something I am overlooking here? Should I be calibrating out the mixer (and cables, etc.) directly somehow? Do I need a filter on the output of the mixer? The only filter I have that will pass the full 1 - 2 GHz band is low pass. I would appreciate any assistance on this. Bruce 0
2019-2-14 16:26:04　　评论淘帖0 邀请回答您可以邀请以下用户，快速回答问题 × kingnet_52040 该类别下有 195 个回答。邀请回答 60user7 该类别下有 81 个回答。邀请回答蓝色冰汐该类别下有 45 个回答。邀请回答醉狼工作室该类别下有 41 个回答。邀请回答 ianwhoani 该类别下有 30 个回答。邀请回答 dkhwakd 该类别下有 25 个回答。邀请回答 aaabbb567 该类别下有 23 个回答。邀请回答 e08506806 该类别下有 20 个回答。邀请回答 szzjfyp 该类别下有 18 个回答。邀请回答 sonia87 该类别下有 16 个回答。邀请回答 ningee 该类别下有 16 个回答。邀请回答 zouqinxiang 该类别下有 15 个回答。邀请回答 xj5548 该类别下有 15 个回答。邀请回答 derek88 该类别下有 14 个回答。邀请回答 daichuangs 该类别下有 14 个回答。邀请回答 hzmbs2016 该类别下有 12 个回答。邀请回答 JST2006 该类别下有 12 个回答。邀请回答 www037 该类别下有 11 个回答。邀请回答 ToGoodSoft 该类别下有 11 个回答。邀请回答 juujwfdf 该类别下有 11 个回答。邀请回答举报周静相关推荐 • 测量噪声系数的方法有哪些？ 1417 • 如何进行噪声系数测量？ 2308 • 请问怎样设计一种在片噪声系数测量系统？ 1180 • 噪声系数测量方法 2563 • 附加天线的LNA噪声系数如何测量 2800 • 射频器件噪声系数有什么测量方法？ 2001 • 利用频谱仪来测量噪声系数 3461 • 噪声系数的含义和测量方法全面介绍 2866 • 多通道射频接收机测量噪声系数的方法 1831 • 手机接收通道噪声系数测试的方法 2178 2个回答

答案对人有帮助，有参考价值 0 我认为你的问题是相反的边带。如果你不删除这个其他边带，你将获得3dB更高的NF。问候Jens 以上来自于谷歌翻译以下为原文 I think your problem is the opposite sideband. If you don't remove this other sideband you'll get 3dB higher NF. Regards Jens

2019-2-14 16:32:59 评论举报陈桂兰

答案对人有帮助，有参考价值 0 zhihuaczh 发表于 2019-2-14 20:51 我认为你的问题是相反的边带。如果你不删除这个其他边带，你将获得3dB更高的NF。问候Jens > {quote：title = sm7ovk写道：} {quote}>我认为你的问题是相反的边带。如果你不删除这个其他边带，你将获得3dB更高的NF。 >问候> Jens实际上，增加的边带使测得的噪声系数低3 dB。这是因为NF测量值是NF =（输出端的噪声功率）/增益通过测量DUT输出端噪声源的噪声功率来测量增益。在这种情况下，噪声源会在所需的和不足的边带处产生功率，因此增益测量为3 dB太高，而nf为3 dB太低（这不完全正确，但足够多）。当然，冷噪声测量是测量混合器中的总噪声，输入仅为50欧姆（与噪声源关闭或冷噪声相同）。输出端的任何双边带噪声都是真实的，需要包括在内。但很可能在LO输出信号的IF BW内，本地振荡器上存在过多的噪声，这些噪声会混合到输出端。这是测量原始混频器的一个非常常见的问题（与转换器相比，转换器通常仅因此而具有LO滤波器）。在这种情况下，无需过滤LO。以上来自于谷歌翻译以下为原文 > {quote:title=sm7ovk wrote:}{quote} > I think your problem is the opposite sideband. If you don't remove this other sideband you'll get 3dB higher NF. > Regards > Jens Actually, the added sideband makes the measureed noise figure appear 3 dB lower. That is because the NF measurement is NF=(Noise power at the output)/Gain The gain is measured by measuring the noise power of the noise source at the output of the DUT. In this case, the Noise Source produces power at both desired and undersired sidebands, and so the gain is measured 3 dB too high, and the nf is 3 dB too low (this is not exactly correct, but cloes enough). Of course, the cold-noise measurement is the measurement of total noise out of the mixer with just 50 ohms on the input (which is the same as noise source off, or cold noise). Any double side-band noise at the output is real, and needs to be included. But most likely there is excess noise on the local oscillator, within the IF BW of the LO output signal, that is getting mixed down to the output. This is a very common problem measuring raw mixers (in contrast to converters, which often have LO filters just for this reason). Nothing to do but filter the LO in this case.

2019-2-14 16:40:48 评论举报孔德羲