Wireless MCUのトピックFxth 8700 https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356584#M146 <HTML><HEAD></HEAD><BODY><P> Hi,</P><P></P><P>I'm using the chip Fxth8700 for a TPMS project.</P><P></P><P>I need help to design the matching network for the antenna (433MHz) , because I'm not expert on that field.</P><P></P><P>Q1) Why there is L1 between Vdd and the RF pin? Which value should it have?</P><P>Q2) Has the RF pin a source impedance of 50 ohms? </P><P></P><P>Thanks,</P><P>Riccardo</P></BODY></HTML> Sat, 07 Feb 2015 16:05:40 GMT riccardocescato 2015-02-07T16:05:40Z Fxth 8700 https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356584#M146 <HTML><HEAD></HEAD><BODY><P> Hi,</P><P></P><P>I'm using the chip Fxth8700 for a TPMS project.</P><P></P><P>I need help to design the matching network for the antenna (433MHz) , because I'm not expert on that field.</P><P></P><P>Q1) Why there is L1 between Vdd and the RF pin? Which value should it have?</P><P>Q2) Has the RF pin a source impedance of 50 ohms? </P><P></P><P>Thanks,</P><P>Riccardo</P></BODY></HTML> Sat, 07 Feb 2015 16:05:40 GMT https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356584#M146 riccardocescato 2015-02-07T16:05:40Z Re: Fxth 8700 https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356585#M147 <HTML><HEAD></HEAD><BODY><P>Hello Ricardo,</P><P></P><P>Please refer to Xtrinsic FXTH87 Family Evaluation Design Reference Manual (<A href="http://cache.freescale.com/files/sensors/doc/ref_manual/FXTH87EDRM.pdf">http://cache.freescale.com/files/sensors/doc/ref_manual/FXTH87EDRM.pdf</A> ).</P><P></P><P>In chapter 3.2.2. you will find recommended values of components in matching network.</P><P></P><P>Regarding your question: in simplest words the function of L1 is to "separate" RF from Vdd at working frequency (315 or 432 MHz).</P><P></P><P>Regards,</P><P>Wlodek</P></BODY></HTML> Mon, 09 Feb 2015 12:47:36 GMT https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356585#M147 Wlodek_D_ 2015-02-09T12:47:36Z Re: Fxth 8700 https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356586#M148 <HTML><HEAD></HEAD><BODY><P>I design the PCB as the referenc, but the matching is not good....</P><P>Set the input power to 0dm,&nbsp;&nbsp; connect it to Spectrum Analyzer by coaxial directly , just -40dBm power is tested.</P><P>It sugest the matching is so bad...</P><P></P><P>How to improve?</P></BODY></HTML> Thu, 10 Mar 2016 14:58:04 GMT https://community.nxp.com/t5/Wireless-MCU/Fxth-8700/m-p/356586#M148 yapingwang 2016-03-10T14:58:04Z