AD8342ACPZ-R2 datasheet(20/25 Pages) AD

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AD8342

Data Sheet

Rev. C | Page 20 of 25

The available frequency range of the AD8342 is extremely

broad. With adequate care, any of the mixer ports can be

optimized for extremely low frequencies, or up to several GHz.

The standard evaluation board is populated for broadband

performance from a few MHz to ~1 GHz. The input match of

the RF port degrades at higher frequencies when using the

standard eval board. The broadband frequency range can be

extended by minimizing parasitics between the input

terminating resistor, R5, and the input pins.

COMM

IFOP

IFOM

COMM

RFCM

RFIN

VPMX

VPDC

PWDN

EXRB

COMM

VPLO

LOCM

LOIN

COMM

AD8342

VPOS

1000pF

0.1µF

VPOS

1nF

LO IN

1.82kΩ

100pF

RF IN

1nF

100Ω

VPOS

1000pF

0.1µF

1nF

0.1µF

100pF

IF OUT

(190MHz)

TC2-1T

0.1µF

NOTES

1. INPUT TERMINATION PLACED AS CLOSE AS POSSIBLE TO RFIN AND RFCM INPUTS.

Figure 53. Modified Evaluation Board Schematic for Broadband

Downconversion Performance up to 3 GHz

The measurements in Figure 54 were made using the modified

evaluation board as configured in Figure 53.

500

3000

RF FREQUENCY (MHz)

1000

1500

2000

2500

GAIN

OIP3

IP1dB

Figure 54. Input OIP3, Input P1dB, Gain, and NF vs. RF Frequency for a

190 MHz IF Using a Low-Side LO

The broadband frequency capabilities of the AD8342 makes it

an attractive solution for a variety of applications, including

cellular, CATV, point-to-point radio links, and test equipment.

As an example, the circuit depicted in Figure 53 can easily be

applied as a feedback mixer in a predistortion receiver design.

The performance depicted in Figure 55 was measured using a

160 MHz IF. Here, four W-CDMA carriers with high PAR are

downconverted for IF sampling so that transmit path

nonlinearities can be measured and minimized using digital

predistortion techniques.

–30

CENTER 160MHz

SPAN 40.6MHz

–50

–40

–70

–60

–90

–80

–110

–100

–120

4.06MHz

POS –22.564dBm

REF –22.6dBm

ATT 5dB

RBW 30kHz

VBW 300kHz

SWT 4s

STANDARD: W-CDMA 3GPP FWD

Tx CHANNELS

CH1 (REF) –20.65dBm

CH2

–20.29dBm

CH3

–20.25dBm

CH4

–20.29dBm

TOTAL

–14.35dBm

ADJACENT CHANNE L

LOWER

–61.36dB

UPPER

–60.84dB

ALTERNATE CHANNEL

LOWER

–61.94dB

UPPER

–61.72dB

Figure 55. ACPR Performance for Multiple W-CDMA Carriers Being

Downconverted from 2140 MHz to 160 MHz for Distortion Analysis

APPLICATIONS ABOVE 3 GHZ

Operation of the AD8342 mixer can be extended above 3 GHz;

however, bandwidth is limited due to on-chip parasitics. By

eliminating all unnecessary parasitics in the LO path, the LO

input voltage standing wave ratio (VSWR) can be kept low up to

4 GHz. Figure 56 shows the circuit configuration for the RF input

frequency of 3.5 GHz to 3.8 GHz. A 22 Ω resistor is added

between the RFCM pin and the 1 nF capacitor to ground, and a

1 pF capacitor is also added to provide the tuning for the desired

frequency range. The resulting RF and LO input return losses

are shown in Figure 57. Using a fixed LO frequency of 3.4 GHz,

the conversion gain response for the RF input frequency range

from 3.5 GHz to 3.8 GHz is shown in Figure 59.

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