Detailed Description

The MAX9996 high-linearity downconversion mixer pro-

vides 8.3dB of conversion gain and 26.5dBm of IIP3,

with a typical 9.7dB noise figure. The integrated baluns

and matching circuitry allow for 50

Ω single-ended inter-

faces to the RF and the two LO ports. A single-pole, dou-

ble-throw (SPDT) switch provides 50ns switching time

between the two LO inputs with 43dB of LO-to-LO isola-

tion. Furthermore, the integrated LO buffer provides a

high drive level to the mixer core, reducing the LO drive

required at the MAX9996’s inputs to a -3dBm to +3dBm

range. The IF port incorporates a differential output,

which is ideal for providing enhanced IIP2 performance.

Specifications are guaranteed over broad frequency

ranges to allow for use in UMTS, cdma2000, and

2G/2.5G/3G DCS1800 and PCS1900 base stations. The

MAX9996 is specified to operate over a 1700MHz to

2200MHz RF frequency range, a 1900MHz to 2400MHz

LO frequency range, and a 40MHz to 350MHz IF fre-

quency range. Operation beyond these ranges is pos-

sible; see the Typical Operating Characteristics for

additional details.

This device can operate in low-side LO injection appli-

cations with an extended LO range, but performance

MAX9994—a variant of the MAX9996—provides better

low-side performance since it is tuned for a lower LO

range of 1400MHz to 2000MHz.

RF Input and Balun

The MAX9996 RF input is internally matched to 50

Ω,

requiring no external matching components. A DC-

blocking capacitor is required because the input is

internally DC shorted to ground through the on-chip

balun. Input return loss is typically 15dB over the entire

1700MHz to 2200MHz RF frequency range.

LO Inputs, Buffer, and Balun

The MAX9996 can be used for either high-side or low-

side injection applications with a 1900MHz to 2400MHz

LO frequency range. For a device with a 1400MHz to

2000MHz LO frequency range, refer to the MAX9994

data sheet. As an added feature, the MAX9996 includes

an internal LO SPDT switch that can be used for fre-

quency-hopping applications. The switch selects one of

the two single-ended LO ports, allowing the external

oscillator to settle on a particular frequency before it is

SiGe High-Linearity, 1700MHz to 2200MHz

Downconversion Mixer with LO Buffer/Switch

8

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Pin Description

PIN

NAME

FUNCTION

1, 6, 8, 14

Application Circuit.

2RF

Single-Ended 50

Ω RF Input. This port is internally matched and DC shorted to GND through a balun.

Requires an external DC-blocking capacitor.

3

TAP

Center Tap of the Internal RF Balun. Bypass to GND with capacitors close to the IC, as shown in the

Typical Application Circuit.

4, 5, 10, 12,

13, 17

GND

Ground

7

LOBIAS

Bias Resistor for Internal LO Buffer. Connect a 549

Ω ±1% resistor from LOBIAS to the power supply.

9

LOSEL

Local Oscillator Select. Logic control input for selecting LO1 or LO2.

11

LO1

Local Oscillator Input 1. Drive LOSEL low to select LO1.

15

LO2

Local Oscillator Input 2. Drive LOSEL high to select LO2.

16

LEXT

External Inductor Connection. Connect a low-ESR, 10nH inductor from LEXT to GND. This inductor

carries approximately 100mA DC current.

18, 19

IF-, IF+

Typical Application Circuit).

20

IFBIAS

IF Bias Resistor Connection for IF Amplifier. Connect an 806

Ω resistor from IFBIAS to GND.

EP

GND

Exposed Ground Paddle. Solder the exposed paddle to the ground plane using multiple vias.