Datasheet

LTC6945
5
6945f
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
C
= 25°C. V
REF
+
= V
REF0
+
= V
D
+
= V
RF
+
= V
VCO
+
= 3.3V, V
CP
+
= 5V unless otherwise
specified. All voltages are with respect to GND.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Phase Noise and Spurious
L
M(MIN)
Output Phase Noise Floor (Note 5) RFO[1:0] = 3, OD[2:0] = 1, f
RF
= 6GHz
RFO[1:0] = 3, OD[2:0] = 2, f
RF
= 3GHz
RFO[1:0] = 3, OD[2:0] = 3, f
RF
= 2GHz
RFO[1:0] = 3, OD[2:0] = 4, f
RF
= 1.5GHz
RFO[1:0] = 3, OD[2:0] = 5, f
RF
= 1.2GHz
RFO[1:0] = 3, OD[2:0] = 6, f
RF
= 1.0GHz
–155
–155
–156
–156
–157
–158
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
L
M(NORM)
Normalized In-Band Phase Noise Floor I
CP
= 11.2mA (Notes 6, 7, 8) –226 dBc/Hz
L
M(NORM –1/f)
Normalized In-Band 1/f Phase Noise I
CP
= 11.2mA (Notes 6, 9) –274 dBc/Hz
L
M(IB)
In-Band Phase Noise Floor (Notes 6, 7, 8, 10) –99 dBc/Hz
Integrated Phase Noise from 100Hz to
40MHz
(Notes 4, 7, 10) 0.13 °RMS
Spurious Reference Spur, PLL locked (Notes 4, 7, 10, 11) –102 dBc
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC6945I is guaranteed to meet the specified performance
limits over the –40°C to 105°C case temperature range.
Note 3: For 0.8V ≤ V
CP
≤ (V
CP
+
– 0.8V).
Note 4: VCO is Crystek CVCO55CL-0902-0928.
Note 5: f
VCO
= 6GHz, f
OFFSET
= 40MHz.
Note 6: Measured inside the loop bandwidth with the loop locked.
Note 7: Reference frequency supplied by Wenzel 501-04608A,
f
REF
= 10MHz, P
REF
= 13dBm.
Note 8: Output phase noise floor is calculated from normalized phase
noise floor by L
M(OUT)
= –226 + 10log
10
(f
PFD
) + 20log
10
(f
RF
/f
PFD
).
Note 9: Output 1/f phase noise is calculated from normalized 1/f phase
noise by L
M(OUT –1/f)
= –274 + 20log
10
(f
RF
) – 10log
10
(f
OFFSET
).
Note 10: I
CP
= 11.2mA, f
PFD
= 250kHz, f
RF
= 914MHz, FILT[1:0] = 3, Loop
BW = 7kHz.
Note 11: Measured using DC1649A.
TYPICAL PERFORMANCE CHARACTERISTICS
REF Input Sensitivity vs
Frequency REFO Output Power vs Frequency REFO Phase Noise
FREQUENCY (MHz)
0
SENSITIVITY (dBm)
–35
–30
–25
200 225
6945 G01
–40
–45
–55
50
100
150
25 250
75
125
175
–50
–15
–20
105°C
25°C
–40°C
BST = 1
FILT = 0
FREQUENCY (MHz)
0
P
OUT
(dBm)
0
1
2
200 225
6945 G02
–1
–2
–4
50
100
150
25 250
75
125
175
–3
4
3
105°C
25°C
–40°C
OFFSET FREQUENCY (Hz)
–155
PHASE NOISE (dBc/Hz)
–150
–145
–140
100 10k 100k 1M 5M
6945 G03
–160
1k
P
OUT
= 1.45dBm
f
REF
= 10MHz
BST = 1
FILT = 3
NOTE 7