ADF4001BCP datasheet(23/28 Pages) AD

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AD8348

Rev. A | Page 23 of 28

LO GENERATION

Analog Devices has a line of PLLs that can be used for

generating the LO signal. Table 4 lists the PLLs and their

maximum frequency and phase noise performance.

Table 4. ADI PLL Selection Table

ADI Model

Frequency FIN

(MHz)

@ 1 kHz ΦN

dBc/Hz,

200 kHz PFD

ADF4001BRU

165

−99

ADF4001BCP

165

−99

ADF4110BRU

550

−91

ADF4110BCP

550

−91

ADF4111BRU

1200

−78

ADF4111BCP

1200

−78

ADF4112BRU

3000

−86

ADF4112BCP

3000

−86

ADF4116BRU

550

−89

ADF4117BRU

1200

−87

ADF4118BRU

3000

−90

ADI also offers the ADF4360 fully integrated synthesizer and

VCO on a single chip that offers differential outputs for driving

the local oscillator input of the AD8348. This means that the user

can eliminate the use of a balun for single-ended-to-differential

conversions. The ADF4360 comes as a family of chips with six

operating frequency ranges. One can be chosen depending on

the local oscillator frequency required. Table 5 shows the

options available.

Table 5. ADF4360 Family Operating Frequencies

ADI Model

Output Frequency Range (MHz)

ADF4360-1

2150 to 2450

ADF4360-2

1800 to 2150

ADF4360-3

1550 to 1950

ADF4360-4

1400 to 1800

ADF4360-5

1150 to 1400

ADF4360-6

1000 to 1250

ADF4360-7

Lower frequencies set by external L

EVALUATION BOARD

Figure 60 shows the schematic for the AD8348 evaluation

board. Note that uninstalled components are indicated with the

OPEN designation. The board is powered by a single supply in

the range of 2.7 V to 5.5 V. Table 6 details the various configu-

ration options of the evaluation board. Table 7 shows the various

jumper configurations for operating the evaluation board with

different signal paths.

Power to operate the board can be fed to a single VS test point

located near the LO input port at the top of the evaluation

board. A GND test point is conveniently provided next to the

VS test point for the return path.

The device is enabled by moving Switch SW11 (at the bottom left

of the evaluation board) to the ENBL position. The device is

disabled by moving SW11 to the DENBL position. If desired, the

device can be enabled and disabled from an external source that

can be fed into the ENBL SMA connector or the VENB test point,

in which case SW11 should be placed in the DENBL position.

The IF and MX inputs are selected via SW12. The switch should

be moved in the direction of the desired input.

Gain Control

For convenience, a potentiometer, R15, is provided to allow for

changes in gain without the need for an additional dc voltage

source. To use the potentiometer, the SW13 switch must be set

to the POT position. Alternatively, an external voltage applied

to either the test point or SMA connector labeled VGIN can set

the gain. SW13 must be set to the EXT position when an

external gain control voltage is used.

LO Input

The local oscillator signal should be fed to the SMA Connector

J21. This port is terminated in 50 Ω. The acceptable LO power

input range is from −12 dBm to 0 dBm and must be at a

frequency double that of the IF/MX frequency. Remember that

the AD8348 uses a 2:1 frequency divider in the LO path to

generate the internally required quadrature-phase-related LO

signals.

IF Input

The IF input should be fed into the SMA connector IFIP. The

VGA must be enabled when this port is used (SW12 in the IF

position). When this IF input is chosen, the signal path includes

a minimum-loss attenuator to transform a 50 Ω input source to

the 200 Ω source impedance level for which the VGA was

designed. This pad provides a very broadband input match at

the expense of an 11.46 dB power attenuation in the input path.

It is very important to take this into account when measuring

the noise and distortion performance of the unmodified board

using the IFIP input; the apparent noise figure will be degraded

by 11.46 dB, and the apparent IIP3 will be 11.46 dB higher than

actual. If full weak-signal performance is desired from the

evaluation board, the attenuator (comprising R31 and R32)

should be removed and replaced with a low-loss RF transformer

providing the desired 4:1 impedance ratio. When a transformer

is used, IFIN should be ac-coupled to ground and not driven

differentially with IFIP.

MX Input

The evaluation board is by default set for a differential MX drive

through a balun (T41) from a single-ended source fed into the

MXIP SMA connector. When the MX inputs are used, the

internal VGA is bypassed. To change to a differential driving

source, T41 should be removed along with Resistor R42. The

0 Ω R43 and R44 resistors should be installed in place of T41 to

bridge the gap between the input traces. This presents a nominal

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