Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsMAX2021ETX+

MAX2021

High-Dynamic-Range, Direct Up-/Downconversion

650MHz to 1200MHz Quadrature Mod/Demod

Maxim Integrated

EXTERNAL

STAGE

MAX2021

I/Q OUTPUTS

Figure 4. Baseband Port Typical Filtering and DC Return Network

3dB PAD DC BLOCK 0°

3dB PAD DC BLOCK 180°

MINI-CIRCUITS

ZFSC-2-1W-S+

0° COMBINER

3dB PADS LOOK LIKE 160I TO GROUND

AND PROVIDES THE COMMON-MODE

DC RETURN FOR THE ON-CHIP CIRCUITRY.

I+

I-

3dB PAD DC BLOCK 0°

3dB PAD DC BLOCK 180°

MINI-CIRCUITS

ZFSCJ-2-1

MINI-CIRCUITS

ZFSCJ-2-1

Q+

Q-

90°

Figure 5. Demodulator Combining Diagram

Power Scaling with Changes

to the Bias Resistors

Bias currents for the LO buffers are optimized by fine

tuning resistors R1, R2, and R3. Maxim recommends

using ±1%-tolerance resistors; however, standard ±5%

values can be used if the ±1% components are not

readily available. The resistor values shown in the

Typical Application Circuit

were chosen to provide

peak performance for the entire 650MHz to 1200MHz

band. If desired, the current can be backed off from

this nominal value by choosing different values for R1,

R2, and R3. Tables 1 and 2 outline the performance

trade-offs that can be expected for various combina-

tions of these bias resistors. As noted within the tables,

the performance trade-offs may be more pronounced

for different operating frequencies. Contact the factory

for additional details.

Layout Considerations

A properly designed PCB is an essential part of any

RF/microwave circuit. Keep RF signal lines as short as

possible to reduce losses, radiation, and inductance.

For the best performance, route the ground pin traces

directly to the exposed pad under the package. The

PCB exposed pad MUST be connected to the ground

plane of the PCB. It is suggested that multiple vias be

used to connect this pad to the lower-level ground

planes. This method provides a good RF/thermal con-

duction path for the device. Solder the exposed pad on

the bottom of the device package to the PCB. The

MAX2021 evaluation kit can be used as a reference for

board layout. Gerber files are available upon request at