EVAL-ADF7021DBZ5 Datasheet, PDF (48/64 Pages) Analog Devices – High Performance Narrow-Band Transceiver IC

ADF7021
REGISTER 1—VCO/OSCILLATOR REGISTER
VCO_BIAS
Data Sheet
XTAL_
BIAS
CLOCKOUT_
DIVIDE
R_COUNTER
ADDRESS
BITS
VA2 VA1
VCO CENTER
FREQ ADJUST
0
0
NOMINAL
0
1
VCO ADJUST UP 1
1
0
VCO ADJUST UP 2
1
1
VCO ADJUST UP 3
RFD1 RF DIVIDE BY 2
0 OFF
1 ON
VCO BIAS
VB4 VB3 VB2 VB1 CURRENT
0
0
0
1
0.25mA
0
0
1
0
0.5mA
.
.
.
.
1
1
1
1
3.75mA
VCL1 VCO
0 INTERNAL L VCO
1 EXTERNAL L VCO
LOOP
VE1 CONDITION
0 VCO OFF
1 VCO ON
CL4 CL3
0
0
0
0
0
0
.
.
.
.
.
.
1
1
XTAL
D1 DOUBLER
0 DISABLE
1 ENABLED
CP1 ^{ICP (mA)}
CP2 RSET 3.6kΩ
0
0
0.3
0
1
0.9
1
0
1.5
1
1
2.1
X1 XTAL OSC
0 OFF
1 ON
XB2 XB1
00
01
10
11
XTAL
BIAS
20µA
25µA
30µA
35µA
Figure 63. Register 1—VCO/Oscillator Register Map
RF R COUNTER
R3 R2 R1 DIVIDE RATIO
0011
0102
....
....
....
1117
CLKOUT
CL2 CL1 DIVIDE RATIO
0
0
OFF
0
1
2
1
0
4
.
.
.
.
.
.
.
.
.
1
1
30
The R_COUNTER and XTAL_DOUBLER relationship is
expressed as follows:
If XTAL_DOUBLER = 0,
PFD = ^XTAL
R _ COUNTER
If XTAL_DOUBLER =1,
PFD = ^{XTAL × 2}
R _ COUNTER
The CLOCKOUT_DIVIDE is a divided-down and inverted
version of the XTAL and is available on Pin 36 (CLKOUT).
Set XOSC_ENABLE high when using an external crystal. If
using an external oscillator (such as TCXO) with CMOS-level
outputs into Pin OSC2, set XOSC_ENABLE low. If using an
external oscillator with a 0.8 V p-p clipped sine wave output
into Pin OSC1, set XOSC_ENABLE high.
The VCO_BIAS bits should be set according to Table 9.
The VCO_ADJUST bits adjust the center of the VCO operating
band. Each bit typically adjusts the VCO band up by 1% of the
RF operating frequency (0.5% if RF_DIVIDE_BY_2 is enabled).
Setting VCO_INDUCTOR to external allows the use of the
external inductor VCO, which gives RF operating frequencies of
80 Hz to 650 MHz. If the internal inductor VCO is being used
for operation, set this bit low.
Rev. B | Page 48 of 64