ADL5358ACPZ-R2 datasheet(19/24 Pages) AD

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ADL5358

Rev. 0 | Page 19 of

APPLICATIONS INFORMATION

BASIC CONNECTIONS

The ADL5358 mixer is designed to downconvert radio

frequencies (RF) primarily between 500 MHz and 1700 MHz to

lower intermediate frequencies (IF) between 30 MHz and

450 MHz. Figure 53 depicts the basic connections of the mixer.

It is recommended to ac-couple the RF and LO input ports to

prevent non-zero dc voltages from damaging the RF balun or

LO input circuit. The RFIN matching network consists of a

series 8 pF capacitor to provide the optimized RF input return

loss for the desired frequency band.

IF PORT

The mixer differential IF interface requires pull-up choke inductors

to bias the open-collector outputs and to set the output match.

The shunting impedance of the choke inductors used to couple

dc current into the IF amplifier should be selected to provide

the desired output return loss.

The real part of the output impedance is approximately 200 Ω,

as seen in Figure 30, which matches many commonly used SAW

filters without the need for a transformer. This results in a voltage

conversion gain that is approximately 6 dB higher than the power

conversion gain, as shown in Table 3. When a 50 Ω output

impedance is needed, use a 4:1 impedance transformer, as shown

in Figure 53.

BIAS RESISTOR SELECTION

The IF bias resistors (R1 and R4) and LO bias resistors (R2 and R5)

are used to adjust the bias current of the integrated amplifiers at the

IF and LO terminals. It is necessary to have a sufficient amount

of current to bias both the internal IF and LO amplifiers to optimize

dc current vs. optimum IIP3 performance. Figure 41, Figure 43,

and Figure 44 provide the reference for the bias resistor selection

when lower power consumption is preferred at the expense of

conversion gain and IP3 performance.

MIXER VGS CONTROL DAC

The ADL5358 features three logic control pins, VGS0 (Pin 24),

VGS1 (Pin 25), and VGS2 (Pin 26), that allow programmability for

internal gate-to-source voltages for optimizing mixer performance

over desired frequency bands. The evaluation board defaults

VGS0, VGS1, and VGS2 to ground. Power conversion gain, NF,

IIP3, and input P1dB can be optimized, as shown in Figure 39

and Figure 40.

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