MICRF505DEV1 Micrel Inc, MICRF505DEV1 Datasheet - Page 15

• Manufacturer Part Number: MICRF505DEV1
• Description: KIT DEV RADIOWIRE 850-950MHZ
• Manufacturer: Micrel Inc
• Series: RadioWire®r
• Type: Transceiver, ISMr

Specifications of MICRF505DEV1

• Frequency: 850MHz ~ 950MHz
• For Use With/related Products: MICRF505
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-1606

Frequency Synthesizer
The MICRF505 frequency synthesizer consists of a
voltage-controlled
oscillator, dual modulus prescaler, programmable
frequency dividers and a phase-detector. The loop-
filter is external for flexibility and can be a simple
passive circuit. The phase detector compares
frequencies of two signals and produces an error
signal which is proportional to the difference
between the input frequencies. The error signal is
used to control a voltage-controlled oscillator (VCO)
which creates an output frequency. The output
frequency is fed through a frequency divider back to
the input of the phase detector, producing a
feedback loop. If the output frequency drifts, the
error signal will increase, driving the frequency in the
opposite direction so as to reduce the error. Thus,
the output is locked to the frequency at the other
input. This input is called the reference and is
October 2006
0001010
0001011
0001100
0001101
0001110
0001111
0010000
0010001
0010010
0010011
A6…A0
M0_7
M1_7
N0_7
N1_7
D7
-
-
-
-
-
-
oscillator
M0_6
M1_6
N0_6
N1_6
D6
-
-
-
-
-
-
(VCO),
N0_5
M0_5
N1_5
M1_5
A0_5
A1_5
a
D5
-
-
-
-
crystal
M0_4
M1_4
N0_4
N1_4
A0_4
A1_4
15
D4
-
-
-
-
derived from a crystal oscillator, which is very stable
in frequency. The block diagram below shows the
basic elements and arrangement of a PLL-based
frequency synthesizer. The MICRF505 has a dual
modulus
resolution. In a dual modulus prescaler the main
divider is split into two parts, the main part N and an
additional divider A, where A < N. Both dividers are
clocked from the output of the dual-modulus
prescaler, but only the output of the N divider is fed
into the phase detector. The prescaler will first divide
by 16. Both N and A count down until A reaches
zero, at which point the prescaler is switched to a
division ratio 16+1. At this point, the divider N has
completed A counts. Counting continues until N
reaches zero, which is an additional N-A counts. At
this point the cycle repeats.
M0_11
M1_11
N0_11
N1_11
M0_3
M1_3
A0_3
N0_3
A1_3
N1_3
D3
prescaler
N0_10
M0_10
N1_10
M1_10
M0_2
M1_2
A0_2
N0_2
A1_2
N1_2
D2
for
increased
M0_9
M0_1
M1_9
M1_1
A0_1
N0_9
N0_1
A1_1
N1_9
N1_1
D1
[phone]
M9999-103106
frequency
M0_8
M0_0
M1_8
M1_0
N0_8
N0_0
N1_8
N1_0
A0_0
A1_0
D0