ADRF6801 datasheet(26/36 Pages) AD

26 / 36 page

ADRF6801

Rev. 0 | Page 26 of 36

Component

Function

Default Condition

C1, C2, C3, C7, C8, C9, C10, C11, C12,

C16, C17, C18, C19, C20, C21, C22,

C23, C24, C25, C26, C27, C28

The capacitors provide the required decoupling of

the supply-related pins.

C1, C8, C10, C12 = 100 pF (0402),

C16, C18, C21, C22 = 100 pF (0402),

C24, C26 = 100 pF (0402),

C7, C9, C11 = 0.1 μF (0402),

C17, C19, C20, C23 = 0.1 μF (0402),

C25, C27 = 0.1 μF (0402),

C3, C2 = 10 μF (0603), C28 = 10 μF (3216)

T1, C5, C6

External LO path. The T1 transformer provides

single-ended-to-differential conversion. C5 and C6

provide the necessary ac coupling.

C5, C6 = 1 nF (0603),

T1 = TC1-1-13+ Mini-Circuits

R16, R14, R58, C31

REFIN input path. R14 provides a broadband 50 Ω

termination followed by C31, which provides the

ac coupling into REFIN. R16 provides an external

connectivity to the MUXOUT feature described in

the P1-6 line of a 9-pin D-sub connector for dc

measurements.

R14 = 49.9 Ω (0402),

R16 = 0 Ω (0402),

R58 = open (0402),

C31 = 1 nF (0603)

R2, R9, R10, R11, R12, R37, R38, R59,

R60, C4, C14, C15, C13

Loop filter component options. A variety of loop filter

topologies is supported using component

placements C4, C13, C14, C15, R9, R10, and R60. R38

and R59 provide connectivity options to numerous

test points for engineering evaluation purposes. R2

provides resistor programmability of the charge

pump current (see Register 4 description). R37

connects the charge pump output to the loop filter.

R12 references the loop filter to the VCO_LDO. Default

values on board provide a loop filter bandwidth of

roughly 130 kHz using a 26 MHz PFD frequency.

R12, R37, R38 = 0 Ω (0402),

R59 = open (0402),

R9, R60 = 10 kΩ (0402),

R10 = 3 kΩ (0402),

R2, R11 = open (0402),

C13 = 6.8 pF (0402),

C4, C14 = 22 pF (0402),

C15 = 2.7 nF (1206)

R3, R4, R5, R21, R22, R23, R39, R40,

R41, R42, R43, R44, R45, R46, R47,

R48, C29, C30, T2, T3, P2, P3

IF I/Q output paths. The T2 and T3 baluns provide a

9:1 impedance transformation; therefore, with a 50 Ω

load on the single-ended IOUT/QOUT side, the center

tap side of the balun presents a differential 450 Ω

to the ADRF6806. The center taps of the baluns are

ac grounded through C29 and C30. The baluns create

a differential-to-single-ended conversion for ease

of testing and use, but an option to have straight

differential outputs is achieved via populating R3,

R39, R23, and R42 with 0 Ω resistors and removing

R4, R5, R21, and R22. P2 and P3 are differential

measurement test points (not to be used as jumpers).

R4, R5, R21, R22, = 0 Ω (0402),

R40, R43, R45, R46 = 0 Ω (0402),

R47, R48 = 0 Ω (0402),

R3, R23, R39, R41, R42, R44 = open (0402),

C29, C30, = 0.1 μF (0402),

T2, T3 = TCM9-1+ Mini-Circuits,

P2, P3 = Samtec SSW-102-01-G-S

R28

RF input interface. R28 provides the single-ended

RF input path to the on-chip RF input balun.

R28 = 0 Ω (0402)

R30, R35, R50, R51, R52, R57, C32,

C33, C34, P1

Serial port interface. A 9-pin D-sub connector (P1)

is provided for connecting to a host PC or control

hardware. Optional RC filters can be installed on

the CLK, DATA, and LE lines to filter the PC signals

through R50 to R52 and C32 to C34. CLK, DATA, and

LE signals can be observed via test points for debug

purposes. R58 provides a connection to the MUXOUT

for sensing lock detect through the P1 connector.

R30, R35, R57 = 0 Ω (0402),

R50, R51, R52 = open (0402),

C32, C33, C34 = open (0402),

P1 = Tyco Electronics 5747840-3

R33, R55, R56, S1

LO select interface. The LOSEL pin, in combination

with the LDRV and LXL bits in Register 5, controls

whether the LOP and LON pins operate as inputs or

outputs. A detailed description of how the LOSEL pin,

LDRV bit, and the LXL bit work together to control

the LOP and LON pins is found in Table 4 under the

LOSEL pin description. Using the S1 switch, the

user can pull LOSEL to a logic high (VCC/2) or a logic

low (ground). Resistors R55 and R56 form a resistor

divider to provide a logic high of VCC/2. LO select

can also be controlled through Pin 9 of J1. The 0 Ω

jumper, R33, must be installed to control LOSEL via J1.

R33 = 0 Ω (0402),

R55, R56 = 10 kΩ (0402),

S1 = Samtec TSW-103-08-G-S

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