OP183_05 Datasheet, PDF (15/16 Pages) Analog Devices – 5 MHz Single-Supply Operational Amplifier

OP183
LOW VOLTAGE FREQUENCY SYNTHESIZER FOR
WIRELESS TRANSCEIVER
The low noise and low voltage operation capability of the
OP183 serves well for the loop filter of a frequency synthesizer.
Figure 39 shows a typical application in a radio transceiver. The
phase noise performance of the synthesizer depends on low
noise contribution from each component in the loop as the
noise is amplified by the frequency division factor of the
prescaler.
The resistors used in the low-pass filter should be of low to
moderate values to reduce noise contribution due to the input
bias current as well as the resistors themselves. The filter cutoff
frequency should be chosen to optimize the loop constant.
CRYSTAL
REFERENCE
OSCILLATOR
PHASE
DETECTOR
3V
OP183
÷
PRESCALER
RF ^VCONTROL
OUT ^VCO
900MHz
Figure 39. Low Voltage Frequency Synthesizer for a Wireless Transceiver
7
QB5A
QB4
B
A
QB2
RB2 RB1
QB9
RB3
R1
JB1
Q1
2
QB3
QB1
CB1
1
R10
R3A
R3AT
R3LT
R3B
QB10
R2
Q2
3
Z1
5
R4A
R11
CC1
R4AT
R4B R4LT
RB4
RB5
QB6
QB7
QD1
Q3
QB12
RB6
Q7
QB8
Q5
CF1
Q4
QB13
QB11
Q8
R9
Q12
QD2
Q6
CC3
R5
CC2
R8
6
QD3
CO
R7
Q11
Q10
QB14
4
Figure 40. OP183 Simplified Schematic
Rev. D | Page 15 of 16