TI TRF2050PW

TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
D
D
D
D
D
D
D
D
1.2-GHz Operation
Two Operating Modes:
– Philips SA7025 Emulation Mode
Pin-for-Pin and Programming
Compatible
– Extended Performance Mode (EPM)
Dual RF – IF Phase-Locked Loops
Fractional-N or Integer-N Operation
Programmable EPM Fractional
Modulus of 1–16
Normal, Speed-Up, and Fractional
Compensation Charge Pumps
2.9-V to 5.1-V Operation
Low-Power Consumption
PW PACKAGE
(TOP VIEW)
CLOCK
DATA
STROBE
VSS
RFIN
RFIN
VCCP
REFIN
RA
AUXIN
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VDD
TSETUP
LOCK/TEST
RF
RN
VDDA
PHP
PHI
VSSA
PHA
description
The TRF2050 is a low-voltage, low-power consumption 1.2-GHz fractional-N/integer-N frequency synthesizer
component for wireless applications. Fractional-N division and an integral speed-up charge pump are used to
achieve rapid channel switching. Two operating modes are available: 1) SA7025 emulation mode in which the
part emulates the Philips SA7025 fractional-N synthesizer and 2) extended performance mode (EPM), which
provides additional features including fractional accumulator modulos from 1 to 16 (compared to only 5 or 8 for
the SA7025) and programmable control of the speed-up mode duration (compared to the SA7025 method of
holding the strobe line high).
Along with external loop filters, the TRF2050 provides all functions necessary for voltage-controlled oscillator
(VCO) control in a dual phase-locked loop (PLL) frequency synthesizer system. A main channel is provided for
radio frequency (RF) channels and an auxiliary channel for intermediate frequency (IF) channels. The
current-output charge pumps directly drive passive resistance-capacitance (RC) filter networks to generate
VCO control voltages. Rapid main-channel frequency switching is achieved with a charge pump arrangement
that increases the current drive and alters the loop-filter frequency response during the speed-up mode portion
of the switching interval.
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright  1998, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
functional block diagram†
DATA
CLOCK
STROBE
2
1
Serial Control Shift Registers
3
Common Registers
EPM Registers
7025 Registers
Conversion and Selection‡
FMOD
RFIN
NF
Control Lines
4
Fraction
Compensation
Fraction
Accumulator
EM
RFIN
5
Compensation
Charge Pump
17
RF
5
N
6
CN
18
8
CL
2
14
32/33 †
Prescaler
Phase
Detector
Main Divider
(N/N+1)
Proportional
Charge Pump
16
PHP
RN
SM
CN
2
NR
EM+EA
REFIN
12
8
Select
1 2 4 8
Reference
Divider
SA
EA
AUXIN
10
PA
4/1
NA
2
8
CL
2
Integral
Charge Pump
CK
13
4
18
Select
12
Phase
Detector
Auxiliary
Divider
Auxiliary
Charge Pump
9
11
† Terminals 4, 7, 12, 15, and 20 are for supply voltage. Terminal 19 is for testing. These terminals are not shown.
‡ Conversion and selection block provides emulation of SA7025 64/65/72 triple-modulus prescaler operation using the TRF2050 32/33
dual-modulus prescaler.
2
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
PHI
LOCK/
TEST
RA
PHA
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
Terminal Functions
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TERMINAL
NAME
NO.
I/O
DESCRIPTION
AUXIN
10
I
Auxiliary channel RF input
CLOCK
1
I
Serial interface clock signal
DATA
2
I
Serial interface data signal
LOCK/
TEST
18
O
Lock detector/test mode output
PHA
11
O
Auxiliary charge pump output
PHI
13
O
Integral charge pump output
PHP
14
O
Proportional charge pump output
RFIN
5
I
Prescaler positive RF input
RFIN
6
I
Prescaler negative RF input
REFIN
8
I
Reference frequency input signal
RA
9
I
Resistor to VSSA sets auxiliary charge pump reference current
RN
16
I
Resistor to VSSA sets proportional and integral charge pump reference current
RF
17
I
Resistor to VSSA sets compensation charge pump reference current
STROBE
3
I
Serial interface strobe signal
TSETUP
19
I
Test setup for pin 18. For lock detect output, pin 19 connects to VCC through a pullup resistor; for test mode output,
pin 19 terminates to ground.
VCCP
VDD
7
Prescaler positive supply voltage
20
Digital supply voltage
VDDA
VSS
15
Analog supply voltage
4
Digital ground
VSSA
12
Analog ground
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage range, VCCP, VDD, VDDA (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.6 V to 5.6 V
Input voltage range, logic signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.6 V to 5.6 V
Operating ambient temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 55°C to 85°C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: Voltage values are with respect to VSSA.
POST OFFICE BOX 655303
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3
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
recommended operating conditions
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MIN
NOM
MAX
2.9
4.8
5.1
Supply voltage, VCCP, VDD, VDDA
High-level input voltage, VIH (CLOCK, DATA STROBE)
0.7 × VDD
Low-level input voltage, VIL (CLOCK, DATA STROBE)
– 0.3
Operating free-air temperature, TA
– 40
UNIT
V
VDD + 0.3
0.3 × VDD
25
V
V
°C
85
dc electrical characteristics VDD = VDDA = VCCP = 3.6 V, over recommended operating free-air
temperature range. internal registers: CN = 128, CL = 1, CK = 3, N = 3969, NF = 1, FMOD = 8,
SM = 0, NA = 296, SA = 0, PA = 1. external components: RN = 18 kΩ, RF = 24 kΩ, RA = 100 kΩ (unless
otherwise noted)
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supply current: I = IDD + ICCP + IDDA
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PARAMETER
ISTANDBY
Total standby supply currents
IMAIN
Operational supply currents
IAUX
Operational supply currents
TEST CONDITIONS
MIN
TYP
EM = EA = 0 (see Notes 2 and 3)
MAX
UNIT
200
µA
EM = 1, EA = 0 (see Note 3)
7.0
mA
EM = 0, EA = 1 (see Note 3)
1.5
mA
ITOTAL
Operational supply currents
EM = EA = 1 (see Note 3)
7.5
NOTES: 2. VRN = VRA = VRF = VDDA
3. For optimum standby and operational current consumption, the following condition should be be maintained:
VDD ≤ VDDA < VDD + 1.
mA
digital interface
PARAMETER
VOH
VOL
High-level output voltage
IIH
IIL
High-level input current
Low-level output voltage
Low-level input current
TEST CONDITIONS
IOH = 2 mA
IOL = – 2 mA
LOCK/TEST
MIN
TYP
MAX
VDD – 0.5
UNIT
V
DATA CLOCK,
DATA,
CLOCK STROBE
0.5
V
10
µA
10
µA
charge pump currents (see Figure 1)
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auxiliary charge pump
PARAMETER
|IPHA|
Output current PHA
∆IPHA
|IPHA|
Relative output current variation PHA (see Figure 1)
∆IPHA
Output current matching PHA (see Figure 1)
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VPHA = 0.5 VDDA
200
250
300
µA
2%
10%
VPHA = 0.5 VDDA
± 50
µA
proportional charge pump, normal mode, VRF = VDDA
PARAMETER
|IPHP-NM|
Output current PHP
∆IPHP-NM
|IPHP-NM|
Relative output current variation PHP (see Figure 1)
∆IPHP-NM
Output current matching PHP (see Figure 1)
4
POST OFFICE BOX 655303
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VPHP = 0.5 VDDA
400
500
600
µA
2%
10%
VPHP = 0.5 VDDA
• DALLAS, TEXAS 75265
± 50
µA
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
charge pump currents (see Figure 1) (continued)
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proportional charge pump, speed-up mode, VRF = VDDA (see the section on speed-up mode operation)
PARAMETER
TEST CONDITIONS
|IPHP-SM|
Output current PHP
VPHP = 0.5 VDDA
∆IPHP-SM
|IPHP-SM|
Relative output current variation PHP (See Figure 1)
∆IPHP-SM
Output current matching PHP (See Figure 1)
MIN
TYP
MAX
2
2.5
3
2%
10%
± 300
VPHP = 0.5 VDDA
UNIT
mA
µA
integral charge pump, speed-up mode, VRF = VDDA (see the section on speed-up mode operation)
PARAMETER
TEST CONDITIONS
|IPHI-SM|
Output current PHI
VPHI = 0.5 VDDA
∆IPHI-SM
|IPHI-SM|
Relative output current variation PHI (see Figure 1)
∆IPHI-SM
Output current matching PHI (see Figure 1)
MIN
TYP
MAX
4.8
6
7.2
2%
8%
VPHI = 0.5 VDDA
UNIT
mA
± 600
µA
MAX
UNIT
fractional compensation proportional charge pump, normal mode, VRN = VDDA
PARAMETER
TEST CONDITIONS
Output current PHP vs fractional numerator
(see Note 4)
|IPHP-F-NM|
VPHP = 0.5 VDDA,
MIN
FNUM = 1
TYP
µA
1.25
NOTE: 4. Fractional compensation current is proportional to the numerator content of the fractional accumulator (FNUM).
charge pump leakage currents, VRN = VRA = VRF = VDDA
PARAMETER
IPHP
IPHI
IPHA
TEST CONDITIONS
MIN
TYP
VPHP = 0.5 VDDA
VPHI = 0.5 VDDA
±10
Output current PHI
Output current PHA
VPHA = 0.5 VDDA
±10
Output current PHP
MAX
±10
UNIT
nA
ac electrical characteristics, VDD = VCCP = VDDA = 3.6 V, TA = 25°C (unless otherwise noted)
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main divider
PARAMETER
fRFIN
RF input frequency
VID_RFIN
Differential RF input power
TEST CONDITIONS
50-W single-ended characteristic impedance; ac-coupled
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
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MIN
– 20
TYP
MAX
UNIT
1.2
GHz
0
dBm
5
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
ac electrical characteristics, VDD = VCCP = VDDA = 3.6 V, TA = 25°C (unless otherwise noted)
(continued)
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auxiliary divider
fAUXIN
ZAUXIN
PARAMETER
TEST CONDITIONS
Auxiliary
y input frequency
q
y (ac-coupled)
(
)
reference divider
PARAMETER
Reference input frequency
VI_REFIN
Reference input voltage
ZREFIN
Reference input
in ut impedance
im edance
MIN
MAX
UNIT
125
70
MHz
MHz
PA = 0:
VDDA = VDD = 4.8 V
VI_AUXIN = 200 mVpp
110
MHz
PA = 1:
VDDA = VDD = 3.6 V
VI_AUXIN = 200 mVpp
40
MHz
PA = 1:
VDDA = VDD = 4.8 V
VI_AUXIN = 200 mVpp
72
MHz
5
Auxiliary input
in ut impedance
im edance
fREFIN
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ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
PA = 0:
VDDA = VDD = 3.6 V
VI_AUXIN= 560 mVpp
VI_AUXIN = 200 mVpp
TEST CONDITIONS
ac-coupled
MIN
TYP
100
kΩ
3
pF
TYP
MAX
UNIT
40
MHz
200
mVpp
100
kΩ
3
pF
timing requirements, serial data interface (see Figure 2)
MIN
MAX
UNIT
10
MHz
fCLOCK
Clock frequency
tw_CLKHI
tw_CLKLO
Clock high time pulse width, CLOCK high
30
ns
Clock low time pulse width, CLOCK low
30
ns
tsu_Data
Setup time, data valid before CLOCK↑
30
ns
th_Data
Hold time, data valid after CLOCK↑
30
ns
th_Strobe
tsu_Strobe
Hold time, STROBE high before CLOCK↑
30
ns
Setup time, STROBE low after CLOCK↑
30
ns
tw_STRBHI
STROBE high time pulse width, STROBE high
50
ns
6
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PARAMETER MEASUREMENT INFORMATION
charge-pump current output definitions
Current
I2
∆ IOUT REL
I1
∆ IOUT MATCH
ISINK
V1
V2
Voltage
ISOURCE
I2
∆ IOUT REL
I1
Figure 1. Charge-Pump Output Current Definitions
The relative output current variation is defined as the percent difference between charge-pump current output
at two charge-pump output voltages and the mean charge-pump current output (see Figure 1):
DIOUT
Ť
I
Ť
REL
OUT MEAN
ǒ Ǔ
Ťǒ ) ǓŤ
+2
I2 – I1
I2
I1
× 100%; with V 1
+ 0.7 V,
V2
+ VDDA–0.8 V.
Output current matching is defined as the difference between charge-pump sinking current output and
charge-pump sourcing current output at a given charge-pump output (see Figure 1).
∆ IOUT MATCH = ISINK – ISOURCE; with V1 ≤ Voltage ≤ V2.
serial-data interface timing
Change
Valid
DATA
tsu_Data
D1
D0
VH
D31
D30
VL
th_Data
tw_CLKLO
tw_CLKHI
VH
CLOCK
VL
th_Strobe
tsu_Strobe
STROBE
VH
tw_STRBHI
VL
Figure 2. Serial-Data Interface Timing
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
7
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
TYPICAL CHARACTERISTICS
MAIN DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND TEMPERATURE
MAIN DIVIDER INPUT POWER
vs
FREQUENCY AND SUPPLY VOLTAGE
0
0
Main Divider Minimum Input Power – dBm
–10
–20
5.1 V
4.4 V
–30
2.9 V
3.6 V
–40
–50
VCCP = VDD = VDDA = 4.8 V
N = 4000
–10
–20
t = 85°C
–30
t = –40°C
t = 25°C
–40
–50
Figure 3
1250
1150
1200
1100
1050
950
1000
900
REFERENCE DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND TEMPERATURE
10
Reference Divider Minimum Input Power – dBm
10
Reference Divider Minimum Input Power –dBm
850
Figure 4
REFERENCE DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND SUPPLY VOLTAGE
TA = 25°C
N = 100
5
0
5.1 V
–5
–10
4.4 V
–15
–20
3.6 V
–25
–30
–35
10
15
20
25
30
35
40
45
50
55
VCCP = VDD = VDDA = 4.8 V
NR = 100
5
0
–5
–10
t = –40°C
–15
–20
t = 25°C
t = 85°C
–25
–30
–35
–40
10
f – Frequency – MHz
20
30
40
Figure 6
POST OFFICE BOX 655303
50
f – Frequency – MHz
Figure 5
8
800
f – Frequency – MHz
f – Frequency – MHz
–40
700
750
500
550
1250
1150
1200
1050
1100
950
1000
850
900
800
750
700
650
600
500
550
650
–60
–60
600
Main Divider Input Power – dBm
TA = 25°C
N = 4000
• DALLAS, TEXAS 75265
60
70
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
TYPICAL CHARACTERISTICS
AUXILIARY DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND SUPPLY VOLTAGE
AUXILIARY DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND TEMPERATURE
5
Auxiliary Divider Minimum Input Power – dBm
Auxiliary Divider Minimum Input Power – dBm
5
TA = 25°C
PA = 1
N = 100
0
–5
–10
3.6 V
–15
4.4 V
5.1 V
–20
–25
–30
–35
–40
–45
–50
–5
–10
t = –40°C
–15
–20
t = 25°C
–25
t = 85°C
–30
–35
–40
–45
–50
5 10 15 20 25 30 35 40 45 50 55 60 65
VCCP = VDD = VDDA = 4.8 V
PA = 1
N = 100
0
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
f – Frequency – MHz
f – Frequency – MHz
Figure 7
Figure 8
AUXILIARY DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND TEMPERATURE
5
5
TA = 25°C
PA = 0
NA = 100
0
–5
–10
Auxiliary Divider Minimum Input Power – dBm
Auxiliary Divider Minimum Input Power – dBm
AUXILIARY DIVIDER MINIMUM INPUT POWER
vs
FREQUENCY AND SUPPLY VOLTAGE
4.4 V
3.6 V
5.1 V
–15
–20
–25
–30
–35
–40
–45
–50
5
25
50
75
100
125
150
175
200
VCCP = VDD = VDDA = 4.8 V
PA = 0
t = –40°C
N = 100
0
–5
–10
–15
t = 85°C
–20
–25
t = 25°C
–30
–35
–40
–45
–50
5
25
f – Frequency – MHz
50
75
100
125
150
175
200
f – Frequency – MHz
Figure 9
Figure 10
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
9
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
TYPICAL CHARACTERISTICS
CH1
S11
1 µFS
2: 37.43 Ω
–160.98 Ω
1.0245 pF
965.000 000 MHz
1: 89.063 Ω
–272.88 Ω
500 MHz
3: 16.773 Ω
–127.36 Ω
1.4 GHz
2
1
3
START 500.000 MHz
STOP 1 400.000 MHz
Figure 11. Typical RFIN Impedance (S11)
10
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
C22
.1 µ F
2
1
OUT
GND
NDK_OSC
VCC
VCONT
TCXO
C30
1000 pF
VOSC1
J3
3
4
OUT
GND
MOD
5
7
8
GND
OUT
GND
GND
6
GND
GND
VT
C20
.1 µ F
4
3
2
1
10
11
12
9
18
C39
100 pF
R15
18
R11
J2
+
C38
1µF
C31
1000 pF
VOSC2
C11
.1 µ F
J1
18
R12
C7
.1 µ F
16 15 14 13
GND
C31
22 pF
.022 µ F
C23
VDD
C33
1000 pF
AUX1_VCO
VCO190–S
AVT
4
5
6
VOSC3
MQE001
VCC
GND
C34
22 pF
C26
22 pF
3
2
VT
VCC
M_VCO
GND
1
GND
GND
GND
MOD
• DALLAS, TEXAS 75265
GND
POST OFFICE BOX 655303
GND
MVT
18
R24
C43
220pF
R26
18
18
R23
100 pF
C9
R10 100 pF
49.9
C8
R25
49.9
STRB
DTA
CLK
220pF
C24
R16
110 k
VSS
9
8
AUX 10
RA
REF
TSET
VDD
PHA
VSSA
PHI
PHP
VDDA
RN
RF
LOCK
U1
TRF2050
AUX
RA
REF
5 RFIN
RFIN 6 RFIN
VDD 7
VCCP
RFIN
AGND 4
1 CLK
2
DATA
3 STRB
11 PHA
12 VSSA
13 PHI
14 PHP
15 VDDA
16 RN
17 RF
18
19 TSETUP
20 VDD
C5
.1 µ F
LOCK/TEST
VDD
Test
3
Lock
1
C19
1800 pF
R21
36 k
C21
.039 µ F
R22
9.1 k
JP1
VDDA
C14
180 pF
0
C13
47 pF
R18
12 k
C17
470 pF
3.9 k
R19
R13
18 k
R17
C18
1200 pF
12 k
R20
C10
.1 µ F
10 k
R9
VDD
R14
30 k
C16
DNP
AVT
C16
180 pF
MVT
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
APPLICATION INFORMATION
Figure 12. Evaluation Board Schematic (Part 1 of 2)
11
12
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
Figure 12. Evaluation Board Schematic (Part 2 of 2)
+
C1
4.7 µ F
C32
.1 µ F
GND HUB AGND
DGND
HUB
VT
1
1k
R5 3
2 W
CW
220
R1
8
NC
7
VO
6
VO
5
NC
VR1
LOCK
LM317LBD
2
VO
3
VO
4
A
1
STROBE
DATA
CLOCK
+
R27
1.8 k
C2
1 µF
VDDA
C29
.1 µ F
VDDA
Note: Evaluation board dc supply circuitry and PC interface only
GND
SUPPLY
POWER
24
12
25
13
11
14
2
15
3
16
4
17
5
18
6
19
7
20
8
21
9
22
10
23
1
VT
1
U2
8
NC
7
VO
6
VO
5
NC
VR2
1k
R6 3
2 W
220
CW
R28
1.8 k
+
VDD
C28
.1 µ F
4N28S 4
1 5
R32
6.2 k
2
C3
1 µF
VDD
6
CLOCK
LM317LBD
R2
2
VO
3
VO
4
A
1
2
4N28S
4
1 5
R31
6.2 k
VT
6
8
NC
7
VO
6
VO
5
NC
VR3
R7
620
270
U4
+
C4
1 µF
R30
2.7 k
6
STROBE
C32
.1 µ F
VOSC1
4N28S 4
2
1 5
R33
6.2 k
LM317LBD
R3
2
VO
3
VO
4
A
1
U3
DATA
R29
1.8 k
VDD
VT
8
NC
7
VO
6
VO
5
NC
VR4
R36
820
U5
6
270
+
C25
1 µF
C35
.1 µ F
VOPTO
MOC8030
LM317LBD
R35
2
VO
3
VO
4
A
1
4
5
VOPTO
2
1
VT
R8
820
C5
1 µF
8
NC
7
VO
6
VO
5
NC
VR6
R38
390
270
+
VT
2
VO
3
VO
4
A
1
LM317LBD
R37
C36
.1 µ F
VOSC2
270
8
NC
7
VO
6
VO
5
NC
VR5
CLOCK
DATA
STROBE
LOCK/TEST
LM317LBD
R4
2
VO
3
VO
4
A
1
LOCK/TEST
R34
1.8 k
+
C37
1 µF
VOSC3
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
APPLICATION INFORMATION
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
APPLICATION INFORMATION
Table 1. TRF2050 Evaluation Board Parts List
DESIGNATORS
DESCRIPTION
VALUE
QTY
SIZE
(mm)
MANUFACTURER
MANUFACTURER
P/N
C1
Capacitor
4.7 uF
1
“A” 3.2x1.6
Venkel
TA010TCM475KAR
C2, 3, 4, 5, 25,
37, 38
Capacitor
1.0 uF
7
“A” 3.2x1.6
Venkel
TA025TCM105KAR
C6, 7, 10, 11, 20,
22, 27, 28, 29,
32, 35, 36
Capacitor
0.1 uF
12
0603 1.6x.08
Murata
GRM39Y5V104Z016
C8, 9, 39
Capacitor
100 pF
3
0603 1.6x.08
Murata
GRM39COG series
C13
Capacitor
47 pF
1
0603 1.6x.08
Murata
GRM39COG series
C14, 16
Capacitor
180 pF
2
0603 1.6x.08
Venkel
C0603COG series
C15
Capacitor
Not Used
C17
Capacitor
470 pF
1
0603 1.6x.08
Murata
GRM39X7R series
C18
Capacitor
1200 pF
1
0603 1.6x.08
Murata
GRM39X7R series
C12, 30, 33
Capacitor
1000 pF
3
0603 1.6x.08
Murata
GRM39X7R series
C19
Capacitor
1800 pF
1
0603 1.6x.08
Venkel
C0603X7R series
C21
Capacitor
.039 pF
1
1210 3.2x2.5
Panasonic
ECH–U1H393JB
C23
Capacitor
.022 uF
1
0603 1.6x.08
Murata
GRM39X7R series
C24, 40
Capacitor
220 pF
2
0603 1.6x.08
Murata
GRM39X7R series
C26, 31, 34
Capacitor
22 pF
3
0603 1.6x.08
Murata
GRM39COG series
R1, 2
Resistor
2
0603 1.6x.08
Panasonic
ERJ–3GSYJ221
R3, 4, 35, 37
Resistor
4
0603 1.6x.08
Panasonic
ERJ–3GSYJ271
R5, 6
Resistor
R7
Resistor
R8, 36
Resistor
R9
Resistor
R10, 25
Resistor
49.9 W
R11, 12, 15,
23, 24, 26
Resistor
R13
Resistor
R14
Resistor
R16
Resistor
R17, 20
Resistor
R18
Resistor
R19
Resistor
R21
Resistor
220 W
270 W
1 kW
0603 1.6x.08
Not Used
2
.25” square
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
2
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
2
0603 1.6x.08
Panasonic
ERJ–3EKF49R9
18 W
6
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
18 kW
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
2
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Venkel
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
4
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
3
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
1
0603 1.6x.08
Panasonic
ERJ–3GSYJ series
620 W
820 W
10 kW
30 kW
110 kW
12 kW
0W
3.9 kW
36 kW
9.1 kW
R22
Resistor
R27, 28, 29, 34
Resistor
R30
Resistor
R31, 32, 33
Resistor
R38
Resistor
U1
Integrated circuit
1
U2, 3, 4
Optoelectronics
3
1.8 kW
2.7 kW
6.2 kW
390 W
POST OFFICE BOX 655303
Bourns
TI
730C–04
• DALLAS, TEXAS 75265
Motorola
3269W001102
CR0603–16W–000J1
TRF2050
4N28S
13
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
APPLICATION INFORMATION
Table 1. TRF2050 Evaluation Board Parts List (Continued)
DESIGNATORS
DESCRIPTION
U5
Optoelectronics
VALUE
1
VR1, 2, 3, 4, 5, 6
Voltage regulator
6
P1
Para. connector
1
J1, 2, 3
SMA connector
TP1 to TP8
Test point
Main VCO
SIZE
(mm)
QTY
730C–04
SO–8
MANUFACTURER
Motorola
MANUFACTURER
P/N
MOC8030S
National
Semiconductor
LM317LM
AMP
747238–4
3
EF Johnson
8
Components Corp.
Voltage-controlled
oscillator
1
Murata
MQE001
TCXO
Temp.-compensated
crystal oscillator
1
Toyocom
TCO–980
AUX VCO
Voltage-controlled
oscillator
1
Vari-L Comp.
Assorted
ATTEN 10 dB
RL 0 dBm
D
142–0701–831
TP–105–01 series
VCO190–S
VAVG 10
10 dB/
MKR D
1.00 kHz
– 48.83 dB
CENTER 926.66977 MHz
RBW 100 Hz VBW 100 Hz
SPAN 10.00 kHz
SWP 802 ms
Figure 13. Close-in Noise at 926.67 MHz; MODULO – 8; NF = 1; CN = 64
14
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
APPLICATION INFORMATION
VAVG 25
10 dB/
ATTEN 10 dB
RL 0 dBm
D
MKR D
30.0 kHz
– 63.17 dB
CENTER 914.1900 MHz
RBW 1 kHz VBW 1 kHz
SPAN 100.00 kHz
SWP 250 ms
Figure 14. Fractional Spurs, fVCO = 914.19 MHz; MODULO – 8; NF = 1; CN = 64
VAVG 25
10 dB/
ATTEN 10 dB
RL 0 dBm
D
MKR D
30.0 kHz
– 63.34 dB
CENTER 939.1500 MHz
RBW 1 kHz VBW 1 kHz
SPAN 100.00 kHz
SWP 250 ms
Figure 15. Fractional Spurs, fVCO = 939.15 MHz; MODULO – 8; NF = 1; CN = 64
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
15
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
APPLICATION INFORMATION
VAVG 25
10 dB/
ATTEN 10 dB
RL 0 dBm
D
MKR D
30.0 kHz
– 64.16 dB
CENTER 914.3700 MHz
RBW 1 kHz VBW 1 kHz
SPAN 100.00 kHz
SWP 250 ms
Figure 16. Fractional Spurs, fVCO = 914.37 MHz; MODULO – 8; NF = 7; CN = 64
VAVG 25
10 dB/
ATTEN 10 dB
RL 0 dBm
D
MKR D
30.0 kHz
– 63.50 dB
CENTER 939.3300 MHz
RBW 1 kHz VBW 1 kHz
SPAN 100.0 kHz
SWP 250 ms
Figure 17. Fractional Spurs, fVCO = 939.33 MHz; MODULO – 8; NF = 7; CN = 64
16
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
serial programming input
The TRF2050 internal registers are programmed using a three-wire (CLOCK, DATA, STROBE) serial interface.
The serial data is structured into 24-bit standard-length or 32-bit long-length words of which one or four bits are
dedicated address bits. The flag LONG in the D-Word determines whether the A0 (LONG = 0) or A1
(LONG = 1) format is applicable. Figures 18 and 19 show the format of the serial data for two modes of TRF2050
operation: SA7025 and EPM, respectively. The least significant bit (LSB) of the C-Word determines the
operational mode of the TRF2050: 0 = SA7025, 1 = EPM.
In SA7025 mode, the TRF2050 emulates the Philips SA7025 with respect to serial programming.
Microcontroller software written for the SA7025 works transparently when the TRF2050 is operated in SA7025
emulation mode.
Figure 2 shows the timing diagram of the serial input. When the STROBE signal is low, the signal on the DATA
input is clocked into a shift register on the positive edges of the CLOCK. When the STROBE signal is high,
depending on the 1 or 4 address bit(s), the data is latched into different working registers or temporary registers.
In order to fully program the synthesizer, four words must be sent: D, C, B, and A. The E-Word is for testing
purposes only.
The A-Word contains new data for the main divider. The A-Word is loaded only when a main divider
synchronization signal is also active. This is done to avoid phase jumps during reprogramming the main divider.
The synchronization signal is generated by the main divider.
When the TRF2050 is operated in SA7025 emulation mode, programming the A-Word sets the main charge
pumps, which are located on outputs PHP and PHI, into speed-up mode, as long as the STROBE is high. When
the TRF2050 is operated in EPM mode, speed-up mode duration is determined by field G in the B-Word.
NOTE:
The C-Word must be sent during the first programming cycle after power-up
in order to set the mode of operation (7025 or EPM).
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17
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
MSB (Last In)
D31
LSB (First In)
D0
WORD
NM2
A1
0
NF
NM1
NM3
CN
NM2
D23
D0
NM2
A0
0
NF
NM1
NM3
PR = 01
NM2
B
1 0 0 0 0 0 0 0
C
1 0 0 1
NA
P
A 0 0 0 0 0 MS
D
1 0 1 0
NR
F L
E
E MO
SM M SA A O N
D G
E
1 1 1 1
CN
CK
CL
PR = 10
PR
RESERVED
SET TO ZERO
T
Figure 18. Serial Word Format for SA7025 Emulation Mode
18
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
Table 2. SA7025 Emulation Serial-Word-Format Function Listing
SYMBOL
BITS
CK
4
Binary acceleration factor for integral charge pump current
FUNCTION
CL
2
Binary acceleration factor for proportional charge pump current
CN
8
Binary current-setting factor for main charge pumps
EA
1
Auxiliary divider enable flag:
0 = disabled
1 = enabled
EM
1
Main divider enable flag:
0 = disabled
1 = enabled
FMOD
1
Fractional-N modulus selection:
0 = modulo 5
1 = modulo 8
LONG
1
A word format selection:
0 = 24-bit A0 format
1 = 32-bit A1 format
MS
2
Mode select
00 = 7025 Emulation Mode
NA
12
Auxiliary divider ratio
NF
3
Fractional-N increment
NM1
12
Number of main divider cycles when prescaler modulus = 64
NM2
8 if PR = 01
4 if PR = 10
Number of main divider cycles when prescaler modulus = 65
NM3
4 if PR = 10
Number of main divider cycles when prescaler modulus = 72
NR
12
Reference divider ratio
PA
1
Auxiliary prescaler select:
0 = divide by 4
1 = divide by 1
PR
2
Prescaler type:
PR = 01; modulus 2 prescaler (64/65)
PR = 10; modulus 3 prescaler (64/65/72)
SA
2
Reference select for auxiliary phase detector
SM
2
Reference select for main phase detector
T
2
Test mode connection of internal signals to the LOCK terminal:
00 = ACCU overflow
01 = Auxiliary divider
10 = Main divider
11 = Reference divider
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19
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
MSB (Last In)
LSB (First In)
D0
D23
WORD
A0
0
NF
N
0
G
CN
CK
M A
CL C C
P P
B
1 0 0 0
C
1 0 0 1
NA
P
A
D
1 0 1 0
NR
E SA E 0 0
SM M
A
E
1 1 1 1
FMOD
RESERVED
SET TO ZERO
MS
T
Figure 19. Serial Word Format for Extended Performance Mode (EPM)
20
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁ
ÁÁÁ
Table 3. Extended Performance Mode Function Table
SYMBOL
BITS
SAME AS
SA7025
MODE
ACP
1
No
Auxiliary charge polarity:
0 = positive
1 = negative
CK
4
Yes
Binary acceleration factor for integral charge pump current
FUNCTION
CL
2
Yes
Binary acceleration factor for proportional charge pump current
CN
8
Yes
Binary current setting factor for main charge pumps
EA
1
EM
1
Yes
Main divider enable flag:
0 = disabled
1 = enabled
FMOD
5
No
Fraction accumulator modulus
G
4
No
Speed-up mode duration (See Table 9)
MCP
1
No
Main charge pump polarity:
0 = positive
1 = negative
MS
2
No
Mode select
01 = Extended Performance Mode
Auxiliary divider enable flag:
0 = disabled
1 = enabled
N
18
No
Overall main divider integer division ratio (NM)
NA
12
Yes
Auxiliary divider ratio
NF
4
No
Fractional-N increment
NR
12
Yes
Reference divider ratio
PA
1
Yes
Auxiliary prescaler select:
0 = divide by 4
1 = divide by 1
SA
2
Yes
Reference select for auxiliary phase detector
SM
2
Yes
Reference select for main phase detector
T
2
Yes
Test mode connection of internal signals to the LOCK terminal:
00 = ACCU overflow
01 = Auxiliary divider
10 = Main divider
11 = Reference divider
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21
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
main divider – general (see Figure 20)
The differential RFIN inputs are amplified to internal ECL logic levels and provide excellent sensitivity (better
than –20 dBm at 1 GHz), making the prescaler ideally suited for direct interface with a VCO. The internal
dual-modulus (32/33) prescaler and counter sections divide the VCO frequency down to the reference phase
detector frequency. The prescaler division ratio (÷32 or ÷33) is controlled by a feedback signal that is a function
of the 18-bit N-field counters. The N-field counter section is composed of two separate counters: a 5-bit
A-Counter and a 13-bit B-Counter. The prescaler divides by 33 until the A-Counter reaches terminal count and
then divides by 32 until the B-Counter reaches terminal count, whereupon both counters reset and the cycle
repeats. The following equation relates the total N division as a function of the 32/33 prescaler:
NTotal = 32 (B – A) + 33(A), where 0 ≤ A ≤ 31, and 31 ≤ B ≤ 8191.
It is not necessary to determine the values of A and B in the equation above; simply program the N field with
the total division ratio desired (fractional effects ignored).
The N-division ratio has a range of 992 ≤ NTotal ≤ 262143.
Structure of N-Word
5-Bit
A-Counter
N
A
13
5
13 Bits
LSB
18-Bit Register
MSB
18
18
N
FMOD
to Phase Detector
B
5 Bits
NF
13-Bit
B-Counter
32/33 Prescaler
RFIN
4
5
18-Bit
Adder
5-Bit
Fraction Accumulator
Figure 20. Main Divider Organization
main divider – SA7025 emulation
The internal triple modulus prescaler configuration of the SA7025 provides for prescaler division ratios of
64/65/72. The TRF2050 has internal conversion logic that allows the TRF2050 to emulate the SA7025 main
divider operation. When operated in SA7025 emulation mode, the TRF2050 is programmed using the SA7025
serial interface format shown in Figure 18. The TRF2050 internal conversion is transparent and need not be
considered under normal use, thereby allowing use of existing SA7025 programming codes without change.
The following equations relate the total N-division as a function of the emulated 64/65 dual-modulus and
64/65/72 triple-modulus prescalers:
NTotal = 64 (NM1 + 2) + 65 (NM2), where PR = 01 and
NTotal = 64 (NM1 + 2) + 65 (NM2) + 72 (NM3 + 1), where PR = 10.
22
POST OFFICE BOX 655303
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
For contiguous channels, the following rules must be observed:
For PR = 01: 61 ≤ NM1 ≤ 4095 and 0 ≤ NM2 ≤ 63, which yields minimum and maximum divide ratios of 4032
and 266303, respectively.
For PR = 10: 14 ≤ NM1 ≤ 4095 and 0 ≤ NM2 ≤ 15, and 0 ≤ NM3 ≤ 15, which yields minimum and maximum divide
ratios of 1096 and 264335, respectively.
main divider – synchronization
The A-Word is loaded only when a main divider synchronization signal is active. This prevents phase jumps
when reprogramming the main divider. The synchronization signal is generated by the main divider, and it is
active while the main divider is counting down from the programmed value. When the main divider reaches its
terminal count, a main divider output pulse is sent to the main phase detector. Also at this time, the loading of
the A-Word is disabled. Therefore, to correctly load the new A-Word, the STROBE signal must be active high
for at least a minimum number of VCO input cycles at RFIN.
main divider – fractional accumulator
The TRF2050 main synthesizer loop can operate as a traditional integer-N feedback PLL or as a fractional-N
feedback PLL. The integer-N feedback loop divides the VCO frequency by integer values of N, which results
in phase detector reference comparisons at the desired channel spacing. A fractional-N feedback loop divides
the VCO frequency by an integer term plus a fractional term, which results in phase detector reference
comparisons at integer multiples of the desired system channel spacing.
Integer-N division: VCO frequency
N = phase detector reference frequency
= channel spacing
Fractional-N division: VCO Frequency
(N + NF/FMOD) = phase detector reference frequency
where 0 ≤ NF < FMOD and 1 ≤ FMOD ≤ 16.
= FMOD × channel spacing
Because the main counter and prescaler sections cannot divide by a fraction of an integer, the fractional-N
division is accomplished by averaging main divider cycles by N and N+1. A fractional accumulator is
programmed with values of NF and FMOD to control the main counter and prescaler sections to divide by N
or N+1.
The fractional accumulator operates modulo FMOD and is incremented by NF at the completion of each main
divider cycle. When the fractional accumulator overflows, division by N+1 occurs. Otherwise, the main counters
and prescaler divide by N; division by N+1 is transparent to the user. Table 4 shows the contents of the fractional
accumulator and the resulting N or N+1 division for two fractional division ratios.
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23
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
Table 4. Fractional Accumulator Operation
NF = 3, FMOD = 8
ACCUMULATOR
NUMERATOR
STATE
NF = 6, FMOD = 8
ACCUMULATOR
NUMERATOR
STATE
3
÷N
6
÷N
6
÷N
4
÷ N + 1, overflow
1
÷ N + 1, overflow
2
÷ N + 1, overflow
4
÷N
0
÷ N + 1, overflow
7
÷N
6
÷N
2
÷ N + 1, overflow
4
÷ N + 1, overflow
5
÷N
2
÷ N + 1, overflow
0
÷ N + 1, overflow
0
÷ N + 1, overflow
For example, suppose that a typical AMPS channel of 953.25 MHz is desired. Because AMPS channel spacing
is 30 kHz, for fractional-N operation the main phase detector reference frequency must be a multiple of 30 kHz;
240 kHz is typical. A value of FMOD = 8 is selected because 240 kHz / 30 kHz = 8. Dividing the channel frequency
by the reference frequency results in 953.13 ÷ 240 kHz = 3971.375 = 3971 + 3/8. This example is shown in
Table 4 where NF = 3 and FMOD = 8. The table shows that over the period of a complete fractional accumulator
cycle, the fractional accumulator overflows three times for every eight main divider cycles. Figure 21 illustrates
the division by N or N+1 for this 3/8 fractional channel example.
Number of Main
Divider Pulses
N
(3971)
N
(3971)
N+1
(3972)
N
(3971)
N
(3971)
N+1
(3972)
N
(3971)
N+1
(3972)
RF Input
Main Divider Out
Figure 21. 3/8 Fractional Channel Main Divider Operation
The mean division over the complete fractional accumulator cycle as shown in Figure 21 is:
+ 3971 ) 3971 ) 3972 ) 3971 )8 3971 ) 3972 ) 3971 ) 3972 + 3971.375
+ 3971 ) 3ń8
1
Therefore, fractional channels are available every 30 kHz or 240 kHz
+ 2408kHz.
FMOD
N
MEAN
main divider – integer channels
In the case where NF = 0, only division by N occurs, and the fractional accumulator is essentially in a steady
state with a numerator of 0. It never increments or overflows. A channel that requires NF = 0 is a pure integer
channel because the fractional term of NF is zero.
FMOD
24
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
main divider – fractional-N sidebands and compensation
Programming a fractional-N channel means the main divider and prescaler divide by N or N + 1 as dictated by
the operation of the fractional accumulator. Because the main divider operation is integer in nature and the
desired VCO frequency is not, the output of the main phase detector is modulated with a resultant fractional-N
phase ripple that produces sideband energy if left uncompensated. This phase ripple is proportional and
synchronized to the contents of the fractional accumulator that is used to control fractional-N sideband
compensation. Only channels that require a nonzero value of NF have the fractional-N sideband energy. The
fractional-N sidebands, which appear at offset frequencies from the VCO fundamental tone, are multiples of
NF/FMOD. Figure 22 shows the fractional-N phase detector ripple for a 3/8 fractional channel.
240 kHz
Main Phase
Detector Reference
Main Phase
Detector VCO
Feedback
Main Phase
Detector Fractional-N
Ripple
Fractional
Accumulator State
0
3
6
1
4
7
2
5
0
Figure 22. Fractional-N Phase Detector Ripple for 3/8 Channel
The TRF2050 has internal circuitry that provides a means to compensate for the phase detector fractional-N
phase ripple, thereby significantly reducing the magnitude of the fractional-N sidebands. Because the current
waveform output of the main PLL proportional charge pumps is modulated with the phase detector fractional-N
phase ripple, a fractional-N compensation charge-pump output is summed with the main PLL proportional
charge pump.
Figure 23 shows the fractional-N ripple magnitude on the main PHP charge-pump output. The magnitude is
essentially constant, and the pulse width is modulated with the contents of the fractional accumulator. The area
under the main PHP charge-pump curve represents the amount of charge delivered to the loop filter network.
In order to minimize fractional-N sidebands in the VCO spectrum, the compensation current waveform is
generated to have equal and opposite sign magnitude area to the main PHP charge pump.
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25
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
Fractional
Accumulator State
Main PHP Charge Pump
Fractional-N Ripple
Magnitude
0
3
6
1
4
7
2
5
0
Pulse-Width
Modulation
mA
µA
Compensation Charge
Pump Fractional-N
Ripple Magnitude
Pulse-Amplitude
Modulation
Figure 23. Main PHP and Compensation Charge Pump Fractional-N Waveforms for 3/8 Channel
The compensation waveform is pulse-amplitude modulated with the contents of the fractional accumulator. The
main PHP pulse magnitude is much larger than the compensation pulse magnitude but the compensation pulse
has a much longer duration than that of the main PHP pulse. The compensation pulse is optimally centered
about the main PHP charge pump pulse in order to avoid additional sideband energy due to the phase offset
between the main and compensation pulses.
The following example illustrates a method for determining correct values for RN, RF, and CN for minimal
fractional-N sidebands based on VCO frequency and reference frequency.
Assumptions:
The main VCO is locked on channel.
953 MHz ± 10 MHz main VCO operation, 942.99 – 962.91 MHz
19.44 MHz reference frequency
240 kHz phase detector reference frequency
500 µA peak main PHP current
1. Determine the fundamental fractional-N pulse width portion of the main PHP charge-pump output waveform
for the lower, upper, and mean frequencies.
Frac
PW–LWR
+ f1
–
PD
N
f
VCO
+ 2401kHz
–
3929
942.99 MHz
+ 132.557 ps,
4012
+ 2401kHz – 962.91
+ 129.815 ps,
MHz
PD
VCO
Frac
) FracPW–UPR + 132.557 ps ) 129.815 ps + 131.186 ps.
PW*LWR
Frac
+
PW–MEAN
Frac
PW–UPR
+ f1
–
N
f
2
2
The mean-unit pulse width of the fractional-N portion of the main PHP charge-pump output waveform over
the VCO frequencies of interest is 131.186 ps. This fundamental pulse width is modulated by the contents
of the fractional accumulator. For the 3/8 fractional-N channel example, the pulse width varies as shown
in Table 5.
26
POST OFFICE BOX 655303
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
Table 5. Main PHP Fractional-N Pulse-Widths and Areas for 3/8 Channel
NF = 3, FMOD = 8
ACCUMULATOR
STATE
MAIN PHP FRACTIONAL PULSE WIDTH
(ps)
MAIN PHP FRACTIONAL AREA
(ps X AMPS)
3
3 x PW–Mean = 393.558
393.558 ps x 500 µA = .196779
6
6 x PW–Mean = 787.116
787.116 ps x 500 µA = .393558
1
1 x PW–Mean = 131.186
131.186 ps x 500 µA = .065593
4
4 x PW–Mean = 524.744
524.744 ps x 500 µA = .262372
7
7 x PW–Mean = 918.302
918.302 ps x 500 µA = .459151
2
2 x PW–Mean = 262.372
262.372 ps x 500 µA = .131186
5
5 x PW–Mean = 655.930
655.930 ps x 500 µA = .327965
0
0 x PW–Mean = 0
0 ps x 500 µA = 0
Table 5 also shows the area of the fractional-N portion of the main PHP charge-pump waveform.1
2. Determine the pulse width of the compensation charge-pump output waveform.
Comp
PW
+ f 1 + 19.441 MHz + 51.440 ns
Ref
3. Determine the fundamental compensation charge-pump current magnitude using the fundamental main
PHP fractional area.
Comp
Frac
Area + 0.065593 psA + 1.275 mA
+
Mag
51.440 ns
Comp
PW
Table 6 shows the magnitude of the compensation pulse as a function of the fractional accumulator.
Table 6. Compensation Pulse Magnitudes for 3/8 Channel
NF = 3, FMOD = 8
Accumulator
Numerator
Compensation Pulse
Magnitude (µA)
3
3 x 1.275 = 3.825
6
6 x 1.275 = 7.651
1
1 x 1.275 = 1.275
4
4 x 1.275 = 5.101
7
7 x 1.275 = 8.926
2
2 x 1.275 = 2.550
5
5 x 1.275 = 6.376
0
0 x 1.275 = 0
4. Using the result of step 3, determine the value of RF to give the fundamental compensation pulse
magnitude.
RF (kW)
+ Comp25
(mA)
Mag
25 + 19.6 kW.
+ 1.275
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27
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION1234
5. Determine the values of CN and RN for the main PHP charge-pump peak current of 500 µA. Assume that
a midrange value of CN equals 128.
RN(kW)
+
ǒ
18.75
CN
256
1
I(mA)
Ǔ
– 0.75
+
ǒ
18.75
128
256
Ǔ
1
– 0.75
0.5 mA
+ 18 kW
6. The value of the fundamental compensation pulse magnitude calculated in step 3 is fixed and the
compensation pulse width calculated in step 2 is also fixed. However, because the VCO can tune over a
significant range of frequencies, the pulse width of the fractional-N portion of the main PHP charge-pump
waveform varies; thus, the area of the same waveform varies. In order to maintain equal areas under the
fractional-N portion of the main PHP charge-pump and compensation waveforms, CN must vary with the
VCO frequency. As the VCO frequency increases, the fractional-N portion of the main PHP charge-pump
waveform pulse width decreases proportionally, thereby decreasing the area under the same waveform.
Therefore, CN is adjusted to equalize the main PHP and compensation waveform areas, as follows:
FracPW-LWR = 132.557 ps for fVCO = 942.99 MHz
FracPW-UPR = 129.815 ps for fVCO = 962.91 MHz
The fundamental area of the fractional-N portion of the main PHP charge-pump waveform (step 1) is
calculated as 0.065593 picosecond x amperes. If you calculate the fundamental area of the fractional-N
portion of the main PHP charge-pump waveform using the actual pulse widths above in place of the average
pulse width calculated in step 1, the fractional-N main PHP areas is obtained as follows:
FracArea-LWR = 132.557 ps – 0.500 mA = 0.066279 ( ps × amps)
FracArea-UPR = 129.815 ps – 0.500 mA = 0.064691 (ps × amps)
The actual areas under the fractional-N portion of the main PHP waveform require slight modification in the
charge-pump current. The variation of CN required for area equalization is determined using a simple ratio
form:
CN
Frac
Area–AVG
+
LWR
Frac
CN
Area–AVG
+ Frac
Frac
CN
Area–UPR
CN
UPR
Area–UPR
AVG
AVG
+ 0.065593
0.066279
128
+ 126
+ 0.065593
0.064691
128
+ 130
Therefore, for this example, CN can vary from 126-130 over the VCO frequency range of 942.99 – 962.91
MHz for optimum fractional-N sideband suppression. Due to component and circuit tolerances, additional
deviations in CN may be appropriate.
auxiliary divider
The input signal on AUXIN is amplified by a single-ended, ac-coupled input buffer/amplifier that has sufficient
sensitivity (200 mVpp at 200 MHz) for direct connection to a typical VCO. The 12-bit (NA) auxiliary divider
incorporates a divide by 1 (PA = 1) or divide by 4 (PA = 0) prescaler. The total division ratio can be expressed
as:
NTotal = 4 x NA where PA = 0
NTotal = NA, where PA = 1 and NA = 4 to 4095
28
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
reference divider
The input signal on REFIN is amplified by a single-ended, ac-coupled input buffer/amplifier that has sufficient
sensitivity (300 mVpp at 50 MHz) for direct connection to a typical TCXO. The 12-bit (NR) reference divider total
division ratio can be expressed as:
NTotal = NR, where NR = 4 to 4095
A four-section postscaler is connected to the output of the reference divider section. The main and auxiliary
synthesizer sections can individually select a reference postscaler division of 1, 2, 4, or 8 by programming fields
SM and SA, respectively (see Figure 24).
MAIN SELECT
SM = “00”
SM = “01”
SM = “10”
Main Phase
Detector
SM = “11”
Reference Input
Divide by NR
÷2
÷2
÷2
AUXILIARY SELECT
SA = “11”
SA = “10”
SA = “01”
Auxiliary
Phase Detector
SA = “00”
Figure 24. Reference Divider
phase detectors
The main and auxiliary synthesizer sections (see Figure 25) incorporate dual D-type flip-flop phase-frequency
detectors (PFD). A PFD has gain with a phase error over a range of ±2π and exhibits an infinite pull-in range.
Dead-band compensation about zero-phase error is provided by forcing the sourcing and sinking charge pumps
to have a minimum on-time of 1/fRef when the loop is operating in a locked condition.
The phase detectors can be programmed for polarity sense. Normally, external system VCOs have a positive
slope control-voltage frequency characteristic. Some VCOs have a negative slope characteristic. The TRF2050
main and auxiliary phase detectors can be programmed for use with positive or negative slope VCOs using the
MCP and ACP fields, respectively, in the B-Word (EPM mode).
For positive slope VCOs: MCP = ACP = 0
For negative slope VCOs: MCP = ACP = 1
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
VDDA
SET
1
Q
D
Reference Divider
/NR
REFIN
Q
CLR
Charge Pump
Output
SET
1
Main or Auxiliary
Reference Divider
/N or /NR
REFIN or AUXIN
Q
D
Q
CLR
VSSA
Figure 25. Main and Auxiliary Phase Detector Circuit
charge-pump current plans
The TRF2050 uses internal band-gap references and external resistors to develop biasing reference currents
for the various charge pumps sections. Three terminals are designated for the external resistors: RN, RF, and
RA. Internal, programmable coefficients CN, CL, and CK are also used. Table 7 shows how the external resistors
are used to achieve desired charge-pump peak currents.
Table 7. Charge Pump Current Plans
PARAMETER
Peak proportional, normal mode current PHP
ǒ
*
PK NM
Ǔ)ǒ
+
ǒ
)
Peak proportional, speed-up mode current
PHP
*
PK SM
+
)
18.75
x CN
256
RN
0.75
Peak auxiliary current PHA
PK
+
ǒ
)
Ǔ
18.75
x CN x 2 CL 1
256
RN
0.75
Peak integral, speed-up mode current PHI
†Peak compensation, normal mode current
)
Ǔ
18.75
x CN
256
RN
0.75
ǒ
*SM + RN18.75
) 0.75
30
Comp
+ RF
PK
Ǔ
)
Ǔ
x CN x CK x 2 CL 1
256
PK
1.25 x 20
RA
MODE
CONDITION
UNIT
Normal
RN in kΩ
mA
Speed-up
RN in kΩ
mA
Speed-up
RN in kΩ
mA
Normal
RF in kΩ
µA
Normal
RA in kΩ
mA
† The compensation charge-pump current is a pulse-amplitude modulated with the contents of the fractional accumulator. See the section on Main
Divider – Fractional-N Sidebands and Compensation.
The average charge-pump current for the PHP, PHI, and PHA terminals is defined by:
I
30
AVG
+ qerror
2p
x I
.
PK
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LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
PRINCIPLES OF OPERATION
loop enable/disable
The main and auxiliary loops can be enabled and disabled by the contents of the enable bits EM and EA,
respectively. When disabled, all currents in the RF input stages are switched off; the bias currents for the
respective charge-pump circuits are switched off as well. When both loops are disabled (EM = EA = 0), the
reference input stage currents are switched off. The reference chain can be turned off because the serial
interface operates independent of the reference input for the loading of serial words.
Table 8. Loop Enable/Disable
EM
EA
0
0
ENABLED
DISABLED
0
1
Auxiliary, Reference
Main,
1
0
Main, Reference
Auxiliary
1
1
Main, Auxiliary, Reference
Main, Auxiliary, Reference
speed-up mode
When the main synthesizer frequency is changed, it may be desirable to increase the loop bandwidth for a short
time in order to achieve a faster lock time. The proportional charge-pump current is increased and the integral
charge-pump current is switched on for the duration of speed-up mode. The section, charge-pump current
plans, illustrates how the charge-pump currents are a function of the external resistor RN and the programmable
coefficients CN, CL, and CK.
The duration of the speed-up mode is determined by the operational mode of the TRF2050 device: enhanced
performance mode (EPM) or SA7025 emulation mode. In EPM mode, the speed-up mode duration is controlled
as a function of the G field in the B-Word and the reference frequency divider period.
Table 9. Speed-Up Mode
G VALUE
0–14
15
DURATIONEPM
[(G+1) × NR × SM × 16]/fREFIN
< (NR × SM)/(fREFIN × 2); which is less than 1/2 a phase detector cycle
When the TRF2050 is operated in SA7025 emulation mode, the speed-up mode duration is a function of the
STROBE signal associated with the A-Word. When the STROBE signal followed by an A-Word write transaction
goes active, the speed-up mode currents begin and persist until the STROBE signal is returned to an inactive
state.
lock detect
The lock condition of the PLL is defined as a phase difference of less than a ±1 cycle on the reference input
REFIN. The LOCK terminal can be polled to determine the synthesizer lock condition of either or both loops.
The lock detect function is described by the Boolean expression:
LOCK
+
ǒ
LD
Main
) EM
Ǔ·ǒ
LD
Aux
Ǔ
) EA
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31
TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
test modes
The LOCK terminal may be used for test operations by terminating pin 19 to ground. When test modes are
enabled, the LOCK terminal is connected to internal nodes of the TRF2050. Test modes are enabled by writing
ones to the two LSBs of the E-Word. Test modes are disabled by terminating pin 19 to VCC through a pull-up
resistor of 10 kΩ.
Table 10. Test Modes
T1
T0
MODE
0
0
Buffered output of the fractional accumulator
0
1
Buffered output of the auxiliary divider
1
0
Buffered output of the main divider
1
1
Buffered output of the reference divider
The test mode can be used to verify the division ratio of the reference divider, the auxiliary divider, and the main
divider and prescaler.
32
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TRF2050
LOW-VOLTAGE 1.2-GHz FRACTIONAL-N/INTEGER-N SYNTHESIZER
SLWS030D– JUNE 1996 – REVISED OCTOBER 1998
MECHANICAL DATA
PW (R-PDSO-G**)
PLASTIC SMALL-OUTLINE PACKAGE
14 PIN SHOWN
0,32
0,19
0,65
14
0,13 M
8
0,15 NOM
4,50
4,30
6,70
6,10
Gage Plane
0,25
1
7
0°– 8°
0,75
0,50
A
Seating Plane
1,20 MAX
0,10
0,10 MIN
PINS **
8
14
16
20
24
28
A MAX
3,10
5,10
5,10
6,60
7,90
9,80
A MIN
2,90
4,90
4,90
6,40
7,70
9,60
DIM
4040064 / D 10/95
NOTES: A.
B.
C.
D.
All linear dimensions are in millimeters.
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion not to exceed 0,15.
Falls within JEDEC MO-153
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33
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