Datasheet
LTC6945
3
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
Reference Output (REFO)
f
REFO
Output Frequency
l
10 250 MHz
P
REFO
Output Power f
REFO
= 10MHz, R
LOAD
= 50Ω
l
–0.2 3.2 dBm
Output Impedance, Disabled 800 Ω
VCO Input (VCO
+
, VCO
–
)
f
VCO
Input Frequency
l
350 6000 MHz
P
VCOI
Input Power Level R
Z
= 50Ω, Single-Ended
l
–8 0 6 dBm
Input Resistance Single-Ended, Each Input
l
97 121 145 Ω
RF Output (RF
+
, RF
–
)
f
RF
Output Frequency
l
350 6000 MHz
O Output Divider Range All Integers Included
l
16
Output Duty Cycle 50 %
Output Resistance Single-Ended, Each Output to V
RF
+
l
111 136 159 Ω
Output Common Mode Voltage
l
2.4 V
RF
+
V
P
RF(SE)
Output Power, Single-Ended,
f
RF
= 900MHz
RFO[1:0] = 0, R
Z
= 50Ω, LC Match
RFO[1:0] = 1, R
Z
= 50Ω, LC Match
RFO[1:0] = 2, R
Z
= 50Ω, LC Match
RFO[1:0] = 3, R
Z
= 50Ω, LC Match
l
l
l
l
–9.7
–6.8
–3.9
–1.2
–6.0
–3.6
–0.4
2.3
dBm
dBm
dBm
dBm
Output Power, Muted R
Z
= 50Ω, Single-Ended, f
RF
= 900MHz, O = 2 to 6
l
–60 dBm
Mute Enable Time
l
110 ns
Mute Disable Time
l
170 ns
Phase/Frequency Detector
f
PFD
Input Frequency
l
100 MHz
Lock Indicator, Available on the STAT Pin and via the SPI-Accessible Status Register
t
LWW
Lock Window Width LKWIN[1:0] = 0
LKWIN[1:0] = 1
LKWIN[1:0] = 2
LKWIN[1:0] = 3
3.0
10.0
30.0
90.0
ns
ns
ns
ns
t
LWHYS
Lock Window Hysteresis Increase in t
LWW
Moving from Locked State to
Unlocked State
22 %
Charge Pump
I
CP
Output Current Range 12 Settings (See Table 5) 0.25 11.2 mA
Output Current Source/Sink Accuracy V
CP
= V
CP
+
/2, All Settings ±6 %
Output Current Source/Sink Matching I
CP
= 250μA to 1.4mA, V
CP
= V
CP
+
/2
I
CP
= 2mA to 11.2mA, V
CP
= V
CP
+
/2
±3.5
±2
%
%
Output Current vs Output Voltage
Sensitivity
(Note 3)
l
0.1 0.5 %/V
Output Current vs Temperature V
CP
= V
CP
+
/2
l
170 ppm/°C
Output Hi-Z Leakage Current I
CP
= 700μA, CPCLO = CPCHI = 0 (Note 3)
I
CP
= 11.2mA, CPCLO = CPCHI = 0 (Note 3)
0.5
5
nA
nA
V
CLMP(LO)
Low Clamp Voltage CPCLO = 1 0.84 V
V
CLMP(HI)
High Clamp Voltage CPCHI = 1, Referred to V
CP
+
–0.96 V
V
MID
Mid-Supply Output Bias Ratio Referred to (V
CP
+
– GND) 0.48 V/V