Dual Mode Cellular Downconverter

869 - 893 MHz

MADCSM0011

M/A-COM Inc. and its affiliates reserve the right to make changes to the

product(s) or information contained herein without notice. M/A-COM makes

no warranty, representation or guarantee regarding the suitability of its

products for any particular purpose, nor does M/A-COM assume any liability

whatsoever arising out of the use or application of any product(s) or

information.

• North America Tel: 800.366.2266 / Fax: 978.366.2266

• Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300

• Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298

Visit www.macom.com for additional data sheets and product information.

V2

3

M/A-COM’s MADCSM0011 is a highly integrated

MMIC dual mode downconverter for operation in

the 800-900 MHz Cellular frequency band.

The

downconverter

provides

exceptional

RF

performance while consuming low DC current and

is packaged in a low cost plastic package.

It is

ideal for lightweight battery operated portable radio

systems.

The MADCSM0011 consists of a single-ended

mixer, an LO buffer amplifier, a single-ended IF

amplifier and a mode switch.

Surface mount

resistors, inductors and capacitors are used in

conjunction with the downconverter to optimize the

trade-offs among performance, tunability and ease

of use.

The sample board schematic shows the

downconverter and required off-chip components.

The mixer is a single-ended mixer that provides

exceptional linearity and isolation with low loss and

no DC current.

An off-chip inductor (L2) and

capacitor (C2) are required to match the output of

the mixer to the input of the IF buffer amplifier.

The IF output is selected by the mode switch. Each

output port is the open drain of the IF buffer

amplifier.

This allows maximum flexibility of the

intermediate frequency and IF filter.

A matching

network such as that shown herein can be used to

match to 50 ohms from the output impedance of

the buffer to the input impedance of the filter at the

85.38 MHz intermediate frequency.

The inductor

also acts as a choke for the DC supply line.

Elements L5, C6 and C7 (CDMA mode) and L6, C8

and C9 (AMPS mode) provide the necessary

impedance transformations.

The LO input port is matched on-chip to 50 ohms.

An LO buffer amplifier amplifies the –10 dBm input

signal to the level required to drive the mixer. The

performance is optimum with a drive level of –7

dBm.

All DC supply lines must be properly bypassed at

RF frequencies to obtain optimum performance

and at a lower frequency to maintain unconditional

stability.

Capacitors C3, C4, C5, C10, C11 and

C12 are RF bypass capacitors for the IFA and

LOA. The value and placement of these capacitors

is

critical

in

determining

the

frequency

response of these amplifiers.

Operating Instructions