ADL5246ACPZN-R7 datasheet(29/36 Pages) AD

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Data Sheet

ADL5246

Rev. A | Page 29 of 36

EVALUATION BOARD

The schematic of the ADL5246 evaluation board is shown in

Figure 82. All RF traces on the evaluation board have a

characteristic impedance of 50 Ω and are fabricated from FR408

material. The traces are grounded coplanar waveguide (GCPWG)

with a width of 25 mils, spacing to ground of 20 mils, and dielectric

thickness of 13 mils. To ensure broadband performance, the inputs

and outputs of AMP1, AMP2, and AMP3 are ac-coupled with

100 pF capacitors.

The bias to AMP1 is provided through the L1 inductor. VPOS1

and VPOS2 provide bias to AMP2. The L2 and L3 inductors

provide a high impedance to the RF signals that might be present

on these pins. The AMP3 bias circuit receives bias from VPOS2.

The AMP3 output receives bias through the L1 inductor. Bypassing

capacitors are recommended on all supply lines to minimize RF

coupling. AMP3 on the ADL5246 evaluation board is configured

for 2.2 GHz operation.

The evaluation board is designed so that the gain control pins of

AMP2 can be controlled individually or in tandem using VGAIN1

and VGAIN2. The gain range is switched by providing the

appropriate logic level to the internal bypass switch via VSW1

and VSW1. See Table 5 for switch control logic information.

By default, the ADL5246 evaluation board is configured to evaluate

each of the amplifiers individually. To configure the evaluation

board to cascade AMP1, AMP2, and AMP3, remove the C9, C13,

C21, and C22 blocking capacitors and install the C10, C12, C18,

and C19 capacitors. The C33, C34, C31, C32, L8, and L7

components are place holders that allow for adding filters between

the gain stages, if required. If a filter is not being used, install a 0 Ω

resistor as a jumper in place of L7 and L8. Inductor L5 is provided

for optional interstage tuning between RFOUT2 and RFIN3.

Table 8. Evaluation Board Configurations Options

Component

Function

Default Value

VCC1, VCC2

VPOS1, VPOS2,

GND1, GND2,

GND3

Power supply and ground test loops.

Installed

R6, R7

Jumpers to connect VPOS1 and VPOS2 to the internal power plane.

R6, R7 = 0 Ω

ADL5246ACPZN the device under test.

Installed

RFIN1, RFOUT1,

RFIN2, RFOUT2,

RFIN3, RFOUT3

RF input and output SMA connecters.

Installed

R8, R9, R10, R11

Jumpers to facilitate the modification of the RF connections between the amplifier blocks.

R8, R9, R10, R11 = 0 Ω

C8, C9

AC coupling capacitors for AMP1.

C8, C9 = 100 pF

C5, C40, C41

Power supply decoupling capacitors for AMP1. Of these three capacitors, C5 must be

located closest to the device.

C5 = 100 pF,

C40 = 0.1 µF,

C41 = 1000 pF

The bias for AMP1 comes through L1 when connected to a 5 V supply. L1 must be high

impedance for the frequency of operation, while providing low resistance for the dc current.

L1 = 100 nH

VSW1, VSW1

Logic control test loops for the AMP2 integrated bypass switch.

Installed

R2, R3, C6, C11

R2 and R3 isolate the switch control pins from the external capacitance. C6 and C11

provide the decoupling.

R2, R3 = 100 Ω,

C6, C11 = 100 pF

VGAIN1, VGAIN2

VGAIN1 and VGAIN2 are test loops to apply the control voltage to the integrated VVAs.

Installed

R4, R5, C14, C15

R4 and R5 isolate the gain control pins from external capacitance. C14 and C15 provide the

decoupling.

R4, R5 = 100 Ω,

C14, C15 = 100 pF

C13, C22

AC coupling capacitors for AMP2.

C13, C22 = 100 pF

C2, C4, C7, C16,

C17, C20

Power supply decoupling capacitors for AMP2. Of these six capacitors, C7 and C16 must be

located closest to the device.

C7, C16 = 100 pF,

C2, C20 = 0.1 µF,

C4, C17 = 1000 pF

L2, L3

The bias for AMP2 comes through L2 and L3 when connected to a 5 V supply. L2 and L3

must be high impedance for the frequency of operation, while providing low resistance for

the dc current.

L2 = 10 nH,

L3 = 100 nH

L5 is an optional tuning element, which can aid gain, bandwidth, and OP1dB in some

circumstances.

L5 = do not install (DNI)

C21, C23

AC coupling capacitors for AMP3.

C21, C23 = 100 pF

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