Detailed description, Applications information, Table 1. component values – Rainbow Electronics MAX2051 User Manual

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MAX2051

SiGe, High-Linearity, 850MHz to 1550MHz
Up/Downconversion Mixer with LO Buffer

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Detailed Description

The MAX2051 high-linearity up/downconversion mixer
provides +35dBm of IIP3, with a typical 7.8dB noise fig-
ure (NF) and 7.4dB conversion loss. The integrated
baluns and matching circuitry allow for 50

Ω single-

ended interfaces to the RF and the LO ports. The inte-
grated LO buffer provides a high drive level to the mixer
core, reducing the LO drive required at the MAX2051’s
input to a -3dBm to +3dBm range. The IF port incorpo-
rates a differential output, which is ideal for providing
enhanced 2RF-LO and 2LO-2RF performance. 2RF-LO
rejection is typically 88dB and 2LO-2RF rejection is typ-
ically 79dB at an RF drive level of -14dBm.

Specifications are guaranteed over broad frequency
ranges to allow for use in VOD, DOCSIS-compatible
Edge QAM modulation, and CMTS. The MAX2051 is
specified to operate over an RF input range of 850MHz
to 1550MHz, an LO range of 1200MHz to 2250MHz,
and an IF range of 50MHz to 1000MHz.

RF Port and Balun

The MAX2051 RF input provides a 50

Ω match when com-

bined with a series 47pF DC-blocking capacitor. This DC-
blocking capacitor is required because the input is
internally DC shorted to ground through the on-chip
balun. The RF port input return loss is typically 12dB over
the RF frequency range of 1000MHz to 1250MHz.

LO Inputs, Buffer, and Balun

The MAX2051 is optimized for high-side LO injection
applications with a 1200MHz to 2550MHz LO frequency
range. The LO input is internally matched to 50

Ω,

requiring only a 47pF DC-blocking capacitor. A two-
stage internal LO buffer allows for a -3dBm to +3dBm
LO input power range. The on-chip low-loss balun,
along with an LO buffer, drives the double-balanced
mixer. All interfacing and matching components from
the LO inputs to the IF outputs are integrated on-chip.

High-Linearity Mixer

The core of the MAX2051 is a double-balanced, high-
performance passive mixer. Exceptional linearity is pro-
vided by the large LO swing from the on-chip LO
buffer. IIP3, 2RF-LO rejection, and noise figure perfor-
mance are typically +35dBm, 88dBc, and 7.8dB,
respectively.

Differential IF Output

The MAX2051 has an IF frequency range of 50MHz to
1000MHz. The device’s differential ports are ideal for
providing enhanced 2RF-LO performance. Single-
ended IF applications require a 1:1 (impedance ratio)
balun to transform the 50

Ω differential IF impedance to

a 50

Ω single-ended system.

Applications Information

Input and Output Matching

The RF and LO ports are designed to operate in a 50

system. Use DC blocks at RF and LO inputs to isolate
the ports from external DC while providing some reac-
tive tuning. The IF output impedance is 50

Ω (differen-

tial). For evaluation, an external low-loss 1:1 balun
transforms this impedance to a 50

Ω single-ended out-

put (see the

Typical Application Circuit

Externally Adjustable Bias

Bias currents for the LO buffer is optimized by fine-tun-
ing resistor R1. The value for R1, as listed in Table 1,
represents the nominal value, which yields the optimal
linearity/performance trade off. Use larger value resis-
tors (up to 125

Ω) to reduce power dissipation at the

expense of some performance loss. Use smaller value
resistors (down to 0

Ω) to increase the linearity of the

device at the expense of more power. Contact the fac-
tory for details concerning recommended power reduc-
tion vs. performance trade-offs. If ±1% resistors are not
readily available, ±5% resistors can be substituted.

DESIGNATION

QTY

DESCRIPTION

SUPPLIER

C1, C9

47pF microwave capacitors (0402)