application note nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 1 of 10 february 2000 NRF402 rf and antenna layout 1. general gerber files for rf layouts have been made for nordic vlsi?s NRF402 single chip 433mhz rf transmitter [1]. three different loop antennas for 433mhz have also been made available. the gerber files for each layout are compressed into the zip archive format. the zip archive files includes a file named readme.wri that must be read before importing the gerber files into the pcb editor. all described layouts should be fabricated on standard 1.6mm double-sided fr4 printed circuit board. 2. rf layout for NRF402 the rf layouts include all necessary circuitry to design the radio frequency part of a short range communication system based on NRF402 . the transmitter data and control lines din, cs and pwr_up are available at the perimeter of the rf layout and should be connected to the digital part of a customer?s application. +3v and gnd are also available at the perimeter of the rf layout. the +3v for the rf part of the application circuit should be filtered separately from the supply voltages of any digital circuitry. star routing is strictly recommended from the +3v supply source to the rf, digital or other parts of the application circuit. all rf layouts presented below are equal except for the antenna connection circuitry. solutions for differential connection to loop antenna and single ended connection to 50 w antenna are presented. 2.1. differential connection to loop antenna figure 1 shows the schematics for rf layout with differential connection to a loop antenna. the pcb layout is shown in figure 2. the loop antenna layouts described in chapter 3 can easily be placed together with this rf layout. the connection points numbered 1, 2 and 3 on the loop antenna layouts should be connected exactly to the corresponding connection points numbered 1, 2 and 3 on the rf layout. if the loop antenna of practical reasons has to be connected further away from the NRF402 , the connection has to be symmetrical and the length of the pcb tracks must not exceed about 6cm. since the loop antenna is a tuned antenna, the tuning of the antenna has to be checked in this case. the gerber files zip archive filename is pcb_NRF402_diff.zip . nan400-06
application note NRF402 rf and antenna layout nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 2 of 10 february 2000 the recommended external components are as given in table 1 . component description size value tolerance units c1 np0 ceramic chip capacitor, (crystal oscillator) 0603 22 pf c2 np0 ceramic chip capacitor, (crystal oscillator) 0603 22 pf c3 x7r ceramic chip capacitor, (supply decoupling) 0603 4.7 nf c4 np0 ceramic chip capacitor, (supply decoupling) 0603 100 pf c5 x7r ceramic chip capacitor, (supply decoupling) 1206 2.2 m f c6 np0 ceramic chip capacitor, (supply decoupling) 0603 100 pf l1 vco inductor, q>45 @ 433 mhz 0603 22 2% nh r1 1/8w chip resistor, (crystal oscillator) 0603 1.0 m w r3 1/8w chip resistor, (transmitter power setting) 0603 22 1) k w x1 crystal - 4.000 2) mhz table 1 recommended external components. 1) see [1]. 2) see [1]. 2.2. single ended connection to 50 w w antenna by using a differential to single ended matching network figure 3 shows the schematics for rf layout with single ended connection to 50 w antenna by using a differential to single ended matching network. the pcb layout is shown in figure 4. the antenna connection point should be as close as possible to the output of the matching network. if the pcb track between the output of the matching network and the antenna connection point of practical reasons has to exceed about 3cm, this track should be carried out as a 50 w microstrip line. for a standard fr4 printed circuit board with 1.54mm substrate thickness and relative dielectric constant e r ? 4.45 at 433mhz, the width of the microstrip line should be 3mm. the gerber files zip archive filename is pcb_NRF402_single_netw-1_1.zip . the recommended external components are as given in table 1 , except for the supply decoupling capacitor c6, with addition of the components in the differential to single ended matching network as given in table 2 . component description size value tolerance units c6 x7r ceramic chip capacitor, (supply decoupling) 0603 1 nf c7 np0 ceramic chip capacitor 0603 1.8 < 0.25 pf c8 np0 ceramic chip capacitor 0603 470 pf c9 np0 ceramic chip capacitor 0603 1.5 < 0.1 pf l2 chip inductor, srf>433 mhz 3) 0603 180 10% nh l3 chip inductor, q>45 @ 433 mhz 0603 22 2% nh l4 chip inductor, q>45 @ 433 mhz 0603 22 2% nh l5 chip inductor 0603 22 2% nh table 2 recommended components in the differential to single ended matching network 3) see [1].
application note NRF402 rf and antenna layout nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 3 of 10 february 2000 c1 22pf 0603 r3 22k 0603 x1 4.000 mhz r1 1m 0603 reference xc1 1 vss 2 vdd 3 vco1 4 vco2 5 lpf 6 ant2 10 ant1 11 vss 12 pwr_up 13 xc2 14 cs 7 rf_pwr 8 din 9 u1 NRF402 433mhz single chip rf transmitter ssoic14 c2 22pf 0603 l1 22nh 0603 c6 100pf 0603 +3v c5 2.2uf 1206 c4 100pf 0603 cs aaaaaaaa din pwr_up 1 2 3 loop antenna connection c3 4.7nf 0603 figure 1 . schematics for rf layout with differential connection to a loop antenna top silk screen bottom silk screen top view bottom view figure 2. rf layout with differential connection to a loop antenna
application note NRF402 rf and antenna layout nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 4 of 10 february 2000 c1 22pf 0603 r3 22k 0603 x1 4.000 mhz r1 1m 0603 reference xc1 1 vss 2 vdd 3 vco1 4 vco2 5 lpf 6 ant2 10 ant1 11 vss 12 pwr_up 13 xc2 14 cs 7 rf_pwr 8 din 9 u1 NRF402 433mhz single chip rf transmitter ssoic14 c2 22pf 0603 l1 22nh 0603 +3v c5 2.2uf 1206 c4 100pf 0603 cs din pwr_up c3 4.7nf 0603 rf out 50 ohm aaaaaaaa l2 180nh 0603 c7 1.8pf 0603 c8 470pf 0603 l3 22nh 0603 l4 22nh 0603 +3v c6 1nf 0603 c9 1.5pf 0603 l5 22nh 0603 figure 3. schematics for rf layout with single ended connection to 50 w antenna by using a differential to single ended matching network top silk screen bottom silk screen top view bottom view figure 4. rf layout with single ended connection to 50 w antenna by using a differential to single ended matching network
application note NRF402 rf and antenna layout nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 5 of 10 february 2000 3. loop antenna layouts a loop antenna with t-match [2] is a good solution for low cost and small size radio modules. three different layout solutions for small rectangular loop antennas are described below. figure 5 shows the geometry of the designed rectangular loop antennas. c1 a 2 a 1 d c2 r q 1 2 3 figure 5. geometry of rectangular loop antenna the loop antenna physical parameters are a 1 = loop antenna length [mm] a 2 = loop antenna width [mm] d = feed length [mm] b = width of loop conductor each antenna is tuned to a resonance frequency of 433mhz with chip capacitors c1 and c2 . for the designed loop antennas, these capacitors should have tolerances better then 5%. the resistor r q controls the q -value of the antenna. all loop antennas are tuned to approximately 400 w with a t-match. the width of the loop conductor for all of the loop antennas is 1mm. there is no ground plane beneath the antennas. table 3 shows a summary of the designed loop antennas. c1 c2 loop antenna a 1 x a 2 [mm] feed length d [mm] value [ pf] tolerance [ pf] value [ pf] tolerance [ pf] r q 4) [k w w ] q-value zo [ w w ] 18x10 22 5.6 0.25 10 0.25 18 55 400 25x15 21.5 3.3 0.1 5.6 0.25 18 55 400 35x20 22.5 1.8 0.1 4.7 0.1 68 68 380 table 3 summary of the loop antennas 4) thick film chip resistor with resistance tolerance 5% or better.
application note NRF402 rf and antenna layout nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 6 of 10 february 2000
application note NRF402 rf and antenna layout revision: 1.1 page of february 2000 4. references 1. product specification NRF402 , ?433mhz single chip rf transmitter?, nordic vlsi asa. 2. application note nan400-03 , ?small loop antennas?, nordic vlsi asa.
application note NRF402 rf and antenna layout nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 page 8 of 10 february 2000 liability disclaimer nordic vlsi asa reserves the right to make changes without further notice to the product to improve reliability, function or design. nordic vlsi does not assume any liability arising out of the application or use of any product or circuits described herein. life support applications these products are not designed for use in life support appliances, devices, or systems where malfunction of these products can reasonably be expected to result in personal injury. nordic vlsi asa customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify nordic vlsi asa for any damages resulting from such improper use or sale. application note. revision date : 29.02.2000. application note order code : 290200-nan400-06 all rights reserved ?. reproduction in whole or in part is prohibited without the prior written permission of the copyright holder.
application note nordic vlsi asa - vestre rosten 81, n-7075 tiller, norway - phone +47 72 89 89 00 - fax +47 72 89 89 89 revision: 1.1 9 10 february 2000 your notes
application note nordic vlsi - world wide distributors main office: vestre rosten 81, n-7075 tiller, norway phone: +47 72 89 89 e-mail: nrf@nvlsi.no visit the nordic vlsi asa website at http://www.nvlsi.no
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