Linear Technology DC1846A Demo Manual page 5

DC1846A RECONFIGURATION
Table 2. Loop Filter Options
LOOP FILTER SELECTION
TYPE RESISTORS
Passive R14 and R16 = 0Ω,
depopulate R13 and
R15
Active R13 (except when
using an external
VCO) and R15 = 0Ω,
depopulate R14 and
R16
TYPICAL DC1846A REQUIREMENTS AND CHARACTERISTICS
PARAMETER
3.3V Power Supply
5V Charge Pump Power Supply
5V VCO Power Supply
REF+, Reference Frequency
RF+ and RF–
Loop Bandwidth
**These values are for the "DC1846A_100MHz.fracnset" file and included VCO.
***Any unused RF output must be terminated with 50Ω, or poor spurious performance may result.
Note: A low noise 100MHz reference frequency, such as the Wenzel 501-04516D OCXO, is recommended. If using a
different frequency, make sure to update the Fref and R_DIV boxes under the System tab in FracNWizard so that Fpfd
is still 50MHz. For example, if a 250MHz clock is used, Fref should be changed to 250MHz and R_DIV to 5. Ref BST
and FILT under the System tab in FracNWizard might need to be changed if the reference frequency and/or power is
different than what is recommended in the table above. More information can be found in the LTC6947 data sheet.
RZ FROM CI FROM
FRACNWIZARD FRACNWIZARD
RZ_P CI1_P in parallel
with CI2_P
RZ_A CI1_A in parallel
with CI2_A
INPUT OR OUTPUT
Input
Input
Input
Input
Two Outputs
–
DEMO MANUAL DC1846A
CP FROM
FRACNWIZARD POWER
CP_P None
CP_A Determined by the
maximum allowed
tune voltage of the
populated VCO (U3
or U4), up to 24V
applied to V+OA
turret
PHYSICAL LOCATION
J9 and J10 banana jacks
J11 and J12 banana jacks
V+VCO turret
J2 SMA connector
J6 and J7 SMA connectors***
Set by loop filter component values
CPINV BOX,
SYSTEM TAB IN
FRACNWIZARD
Unchecked
Checked
DETAILS
Low noise and spur-free 3.3V,
103mA**
Low noise and spur-free 5V,
22mA**
Low noise and spur-free 5V,
30mA**
Low noise 100MHz**, 6 to 10dBm
into 50Ω, see Note
2328 to 2536MHz** in 190.7Hz**
steps, 0dBm
30.7kHz**
dc1846af
5