AN31 SILABS [Silicon Laboratories], AN31 Datasheet - Page 3

• Manufacturer Part Number: AN31
• Description: INDUCTOR DESIGN FOR THE Si41XX SYNTHESIZER FAMILY
• Manufacturer: SILABS [Silicon Laboratories]

4. Checking the Value of L
Once the desired inductor has been implemented, and
the PCB has been fabricated, the value of L
be verified. This can be done by following the steps
listed below:
1. Measure the minimum operating frequency of the
VCO in open-loop mode. This is accomplished by
performing a sequence of register writes as
described below.
For the IF synthesizer:
synthesizer
For the RF1 synthesizer:
synthesizer
For the RF2 synthesizer:
synthesizer
After programming the VCO to its minimum open-
loop frequency, measure the value of f
this sequence of register writes leaves the device in
a test mode. All the registers described in the data
sheet should be re-written with normal values for
proper closed-loop operation.
A. 0x000062 (hexadecimal)—power IF
B. 0x00024F—test register.
C. 0x000F2D—test register.
D. 0x010010—set the test bit in the main
E. 0x07FF1D—set the VCO to its minimum
A. 0x000052 (hexadecimal)—power RF
B. 0x010003—dummy write to select RF1
C. 0x00024F—test register.
D. 0x000F2D—test register.
E. 0x010010—set the test bit in the main
F. 0x07FF0D—set the VCO to its minimum
A. 0x000052 (hexadecimal)—power IF
B. 0x010004—dummy write to select RF2
C. 0x00024F—test register.
D. 0x000F2D—test register.
E. 0x010010—set the test bit in the main
F. 0x07FF0D—set the VCO to its minimum
and reference amplifier.
configuration register.
frequency.
and reference amplifier.
synthesizer.
configuration register.
frequency.
and reference amplifier.
synthesizer.
configuration register.
frequency.
EXT
MIN
EXT
. Note that
should
Rev. 1.3
2. Measure the maximum operating frequency of the
3. Calculate the measured center frequency for the
VCO in open-loop mode. This is accomplished by
performing a sequence of register writes as
described below.
For the IF synthesizer:
synthesizer
For the RF1 synthesizer:
synthesizer
For the RF2 synthesizer:
synthesizer
After programming the VCO to its maximum open-
loop frequency, measure the value of f
this sequence of register writes leaves the device in
a test mode. All the registers described in the data
sheet should be re-written with normal values for
proper closed-loop operation.
synthesizer using Equation 7.
where f
A. 0x000062 (hexadecimal)—power IF
B. 0x00024F—test register.
C. 0x000F2D—test register.
D. 0x010010—set the test bit in the main
E. 0x00001D—set the VCO to its maximum
A. 0x000052 (hexadecimal)—power RF
B. 0x010003—dummy write to select RF1
C. 0x00024F—test register.
D. 0x000F2D—test register.
E. 0x010010—set the test bit in the main
F. 0x00000D—set the VCO to its maximum
A. 0x000052 (hexadecimal)—power IF
B. 0x010004—dummy write to select RF2
C. 0x00024F—test register.
D. 0x000F2D—test register.
E. 0x010010—set the test bit in the main
F. 0x00000D—set the VCO to its maximum
MEAS
f
and reference amplifier.
configuration register.
frequency.
and reference amplifier.
synthesizer.
configuration register.
frequency.
and reference amplifier.
synthesizer.
configuration register.
frequency.
MEAS
= measured center frequency
=
f
----------------------------- -
MIN
+
2
f
MAX
(Equation 7)
MAX
AN31
. Note that
3