1995 Jun 27
2
Philips Semiconductors
Product specification
Low-voltage dual frequency
synthesizer for radio telephones
UMA1018M
FEATURES
Low current from 3 V supply
Fully programmable RF divider
3-line serial interface bus
Second synthesizer to control first IF or offset loop
frequency
Independent fully programmable reference dividers for
each loop, driven from external crystal oscillator
Dual phase detector outputs to allow fast frequency
switching
Integrated digital-to-analog converter
Dual power-down modes.
APPLICATIONS
900 MHz mobile telephones
Portable battery-powered radio equipment.
GENERAL DESCRIPTION
The UMA1018M BICMOS device integrates prescalers,
programmable dividers, and phase comparators to
implement two phase-locked loops. The device is
designed to operate from 3 NiCd cells, in pocket phones,
with low current and nominal 5 V supplies.
The principal synthesizer operates at RF input frequencies
up to1.25 GHz the auxiliary synthesizer operates at
300 MHz. The auxiliary loop is intended for the first IF or to
transmit offset loop-frequency settings. Each synthesizer
has a fully programmable reference divider. All divider
ratios are supplied via a 3-wire serial programming bus.
Separate power and ground pins are provided to the
analog and digital circuits. The ground leads should be
externally short-circuited to prevent large currents flowing
across the die and thus causing damage. Digital supplies
V
DD1
and V
DD2
must also be at the same potential. V
CC
must be equal to or greater than V
DD
(i.e. V
DD
= 3 V and
V
CC
= 5 V for wider tuning range).
The principal synthesizer phase detector uses two charge
pumps, one provides normal loop feedback, while the
other is only active during fast mode to speed-up
switching. The auxiliary loop has a separate phase
detector. All charge pump currents (gain) are fixed by an
external resistance at pin I
SET
(pin 14). Only passive loop
filters are used; the charge-pumps function within a wide
voltage compliance range to improve the overall system
performance. An on-chip 7-bit DAC enables adjustment of
an external function, such as the temperature
compensation of a crystal oscillator in Global System for
Mobile communications (GSM).
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
V
CC
≥
V
DD
auxiliary synthesizer in
power-down mode
principal and auxiliary
synthesizers ON
MIN.
TYP.
MAX.
UNIT
V
CC
, V
DD
I
CC
+ I
DD
supply voltage
principal synthesizer supply current
2.7
7.7
5.5
V
mA
principal and auxiliary synthesizer
supply current
I
CCPD
, I
DDPD
current in power-down mode per supply
f
VCO
principal input frequency
f
AI
auxiliary input frequency
f
XTAL
crystal reference input frequency
f
PPC
principal phase comparator frequency
f
APC
auxiliary phase comparator frequency
T
amb
operating ambient temperature
10
mA
50
20
3
30
12
200
200
1250
300
40
+85
μ
A
MHz
MHz
MHz
kHz
kHz
°
C