micrf112 Micrel Semiconductor, micrf112 Datasheet - Page 12

• Manufacturer Part Number: micrf112
• Description: Qwikradio Uhf Ask/fsk Transmitter
• Manufacturer: Micrel Semiconductor

Functional Description
Figure 3 shows a functional block diagram of the
MICRF112 transmitter. The MICRF112 can be best
described as a phase locked transmitter. The system
can be partitioned into six functional blocks; crystal
oscillator, PLL×32, power amplifier, enable control,
under voltage detect and open drain switch for FSK
operation.
Crystal Oscillator
The
configuration. It is designed to accept crystals with
frequency from 9.375MHz to 14.0625MHz.
Crystal Oscillator Parameters for ASK Operation
Figure
configuration for ASK operation. The reference oscillator
is capable of driving crystals with ESR range from 20Ω
to 300Ω.
When the ESR of crystal is at 20Ω, the crystal parameter
limits are:
Functional Diagram
Micrel, Inc.
March 2008
ESR 20Ω
C
C
PAR
MO
reference
10 to 40fF
4
2 to 10pF
shows
oscillator
a
Figure 3. Functional Block Diagram MICRF112 10 Pin ASK / FSK Version
reference
is
crystal-based
oscillator
Pierce
circuit
12
When the ESR of crystal is at 300Ω, the crystal
parameter limits are:
ESR
C
C
C
PAR
MO
LOAD
Figure 4. Reference Oscillator ASK Operation
300Ω
2 to 5pF
10 to 40fF
10 to 30pF
[phone]
M9999-031008
MICRF112