AMIS-52000 Datasheet, PDF (11/15 Pages) AMI SEMICONDUCTOR – Single-Chip Radio Transceiver

AMIS-52000 Single-Chip Radio Transceiver
Data Sheet
VCO1, VCO2, VCO Tuning
The AMIS-52000 has an internal Voltage Controlled
Oscillator (VCO). A parallel LC circuit (tuned to twice the
desired RF frequency) is connected between the VCO1 and
VCO2 pins to set the frequency of the VCO.
There is a secondary requirement in the selection of the
components for this function. When the component values
meet the above resonant requirements, the loop
filter voltage should be about in the mid range of the
Figure 6 – Frequency Tuning Components for 433.92MHz
supply voltage (Vloopfilter = (1/2) the VCC supply).
Different combinations of the L and C should be tried until
this secondary requirement is also met.
This circuit is sensitive to the PCB board layout. The
components should be located as close as possible to the
AMIS-52000 part.
The parallel LC circuit tunes the internal VCO frequency.
The frequency is determined by the following:
Frequency = (2) * (Rxfreq) MHz
ctot = CAP + 2.25 pF
INDUCTOR = 1/((Ctot) * ((2πF)^2)))
More detailed information on this function is found in the
AMIS application note, “AMIS-52000 Extending the AMIS-
52000 Frequency Range Beyond the 433MHz Target.”
LPFFILT
The AMIS-52000 uses a Phase Locked Loop to set the
frequency stability of the oscillators. This circuit requires an
external LOOP FILTER connected to pin LPF. The following
second order loop filter is suggested. The components for
this filter should be located as close to the AMIS-52000 part
as possible in the PCB layout. More detailed information on
the design of this filter is found in the AMIS application
note, “AMIS-52000 Extending the AMIS-52000 Frequency
Range Beyond the 433MHz Target.”
Figure 7 – Typical Loop Filter Design
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