CMOSTEK CMT2210A Скачать руководство пользователя страница 4

Страница: 4 / 10

AN107

Rev 1.0 | Page 4/10

www.hoperf.com

3. CMT2210A PCB Layout Recommendations

The following PCB layout design guidelines take the CMT2210A-EM as an example.

CMT2210A-EM is a 2-layer PCB using FR4 PCB material. The thickness of the PCB is 0.8 mm; the thickness for

the copper is 1 ounce (0.0356mm); the separation between ground pour copper and traces/pads is 0.3 mm; the

dielectric constant (Er) for the FR4 material is 4.4. In general, the impedance of the coplanar transmission line is in

proportion to the thickness of the PCB and the distance between the routing and grounding around it. It is in inverse

proportion to the width/thickness of the routing and the dielectric constant (Er). Using a conventional transmission

line calculator (such as Txline), a 1-

mm width of the 50 Ω coplanar transmission line can be obtained.

3.1 CMT2210A-EM PCB Layout

The PCB layout as shown in Figure 2 has six sections. They are RF Input, Power Supply Decoupling, XTAL Circuit,

VCO Tank Circuit, Digital Signals Routing, and Grounding.

RF Input

Power Supply
Decoupling

VCO Tank

Grounding

XTAL

Routing Digital
Signals

Figure 2. CMT2210A-EM PCB Layout

Содержание CMT2210A

Страница 1: ...reless applications The chip is part of the CMOSTEK NextGenRFTM family which includes a complete line of transmitters receivers and transceivers To give the CMT2210A schematic design guidelines an exa...

Страница 2: ...d be within 60 in order to ensure a reliable start up The total tolerance is 20 ppm typically which include initial tolerance crystal loading aging and temperature dependence The acceptable tolerance...

Страница 3: ...ce clock input 10 nRSTO O Active low power on reset output to reset an external MCU 11 VCOP IO VCO tank connected to an external inductor 12 VCON 13 15 GND I Ground 14 RFIN I RF input 16 VDD I Power s...

Страница 4: ...transmission line is in proportion to the thickness of the PCB and the distance between the routing and grounding around it It is in inverse proportion to the width thickness of the routing and the di...

Страница 5: ...ignal routing should be smooth to avoid the impedance variation on the transmission lines which will result in RF signal reflection and performance inconsistency in mass production Wherever possible t...

Страница 6: ...d as this may shift the crystal DC operating point and result in duty cycle variation The XTAL circuit is shown in the figure below Figure 5 XTAL Circuit Layout 3 1 4 Digital Signals Routing The digit...

Страница 7: ...his port To minimize the radiation from the VCO circuit and maintain the high Q factor of the VCO tank L2 should be placed as close as possible to the CMT2210A The VCO tank is surrounded by a solid gr...

Страница 8: ...us ground plane metallization as possible 2 Place a series of ground vias along the PCB edges if possible The maximum distance between the vias should be less than 10 This is required to reduce the PC...

Страница 9: ...AN107 Rev 1 0 Page 9 10 www hoperf com 4 Document Change List Table 3 Document Change List Rev No Chapter Description of Changes Date 0 9 Initial released version 2014 06 14 1 0 2014 06 30...

Страница 10: ...is assumed for inaccuracies and specifications within this document are subject to change without notice The material contained herein is the exclusive property of CMOSTEK and shall not be distribute...