UMA1016XT Datasheet, PDF (12/16 Pages) NXP Semiconductors – Frequency synthesizer for radio communication equipment

Philips Semiconductors
Frequency synthesizer for
radio communication equipment
Product specification
UMA1016xT
APPLICATION INFORMATION
In a typical single-synthesizer application, the circuit is
connected as shown in Fig.6. Both analog and digital
supplies are decoupled to ground with HF and LF filter
capacitors. Correct oscillator operation requires capacitors
both to ground and to provide feedback across the
amplifier. Five signals are shown fed from a
microcontroller to provide serial programming, control
TDD frequency selection and initiate the power-down
mode. Other system logic may also be clocked by a crystal
frequency output from the synthesizer.
A passive 2nd-order loop filter giving a 3rd-order system
response is shown in Fig.6. Indicated values are intended
for rapid frequency switching (500 µs), 200 kHz channel
spacing (reference ÷27) and breakthrough levels below
−60 dB. The VCO output shows a power splitter supplying
both the synthesizer RF input and drive buffer for other
system components (RF amplifier in transmit mode, input
mixer in receive mode). The minimizing of loop filter node
leakage currents requires careful board layout.
handbook, full pagewidth
68 pF
220
pF
33 pF
5.4 MHz
VP
33
Ω
VP
REFCK
47
10 nF
µF
1
nF
100
Ω
RFout ^{12 Ω}
82 Ω
12 Ω
1
16
2
15
3
14
4
13
UMA1016XT
5
12
P4
6
11
P3
7
10
P2
8
9
P1
10
47
nF
µF
VCO
P0
18 kΩ
330 pF
4.7
nF
MGA197 - 2
1995 Jul 12
Fig.6 Application diagram.
12