Circuit For Expanding Antenna Tuning Range To Higher Values; Capacitor Values For Expanding Antenna Tuning Range To Lower Values - Texas Instruments 2000 Series Reference Manual

Appendix A
The antenna tuning inductance range can be increased to 37.6 µH in 7 ranges, as shown in
and Table A-2.
As shown, three capacitors (C1, C2, C3) are connected in series with the antenna coil. The specification
for these capacitors is listed below:
Capacitor type:
• Polypropylene film capacitor
• Minimum 1250 VDC operating voltage
• Capacitance: 47 nF ±2.5%
• Type: SIEMENS "KP" or WIMA "FKP1"
In addition to C1, C2 and C3, the capacitor C4 must be connected in parallel to the RFM antenna
terminals. Different capacitor values are used for each range, the values being given in
ANT 2
ANT 1
Figure A-2. Circuit for Expanding Antenna Tuning Range to Higher Values
34 Expanding Antenna Tuning Inductance Range
Table A-1. Capacitor Values for Expanding Antenna
Tuning Range to Lower Values
Antenna inductance range
24.1 µH to 25.9 µH
22.3 µH to 24.0 µH
20.4 µH to 22.2 µH
18.4 µH to 20.3 µH
16.5 µH to 18.3 µH
13.7 µH to 16.4 µH
Capacitor value
C1, C2, C3, C4 = 3.3 nF
C1, C2, C3, C4 = 6.8 nF
C1, C2, C3, C4 = 11 nF
(10 nF and 1 nF in parallel)
C1, C2, C3, C4 = 16 nF
C1, C2, C3, C4 = 22 nF
C1, C2, C3, C4 = 32 nF
C1
C4
C2
C3
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Figure A-2
Table A-2.
SCBU022 – November 2002
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