SP5070 Datasheet, PDF (3/7 Pages) Mitel Networks Corporation – 2.GHz Fixed Modulus Frequency Synthesiser

FUNCTIONAL DESCRIPTION
The SP5070, when used with a voltage controlled
oscillator, forms a complete phase locked loop frequency
synthesiser.
The phase comparator comparison frequency is
obtained by dividing the reference frequency. This may be
generated on-chip by means of an external crystal, or from
an external reference oscillator.
The output of the prescaler is divided by the fixed
modulus divider, producing an output frequency which is
phased locked to the comparison frequency.
The divider stages are arranged to give a fixed ratio
between the synthesised frequency and the reference of
256:1. Any frequency within the range of 300MHz to 2.4GHz
may be achieved by using the appropriate reference or
crystal frequency.
SP5070
A single external transistor, driven from the charge
pump output, provides the output drive necessary for the
oscillator varicap line.
A test facility which disables the charge pump is also
provided. This is activated when a negative voltage is
applied to pin 11, see electrical characteristics above. When
the device is in this mode, F_COMP and F_DIV are also available
at outputs TEST1 and TEST2 respectively. These are open
collector outputs and are each capable of sinking a minimum
of 1mA. In normal mode of operation these outputs are high
impedance.
For compatibility with SP5060/SP5062, pin 11 may be
connected toV_CC
FROM
VCO
+5V
1n
1
14
1n
2 _S 13
3 P 12
4
5
0
11
5 7 10
6⁰9
7
8
180n _+30V
47n
4MHz
68p
REFERENCE
CRYSTAL
47P
22K
2N3904
22K
10K
VARICAP
47K ^{INPUT VCO}
10n
Fig.3 Typical application and test circuit (1024MHz with 4MHz reference crystal)
+5V
FROM
VCO
1n
1
14
1n
2 _S 13
3 P 12
4
5
0
11
100p
FROM
5 7 10
REFERENCE
0
OSCILLATOR
6
9
180n _+30V
7
8
47n
DP
22K
2N3904
22K
10K
VARICAP
VCO
47K ^INPUT
10n
Fig.4 Application using external reference oscillator
3