MAX19994AETX+T Maxim Integrated Products, MAX19994AETX+T Datasheet - Page 24

• Manufacturer Part Number: MAX19994AETX+T
• Description: RF Mixer Dual SiGe High-Linea rity 1200-2000MHz Do
• Manufacturer: Maxim Integrated Products

Specifications of MAX19994AETX+T

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Dual, SiGe, High-Linearity, 1200MHz to 2000MHz
Downconversion Mixer with LO Buffer/Switch
details). Operation beyond these ranges is possible;
see the Typical Operating Characteristics for additional
information.
Although this device is optimized for a 1450MHz to
2050MHz LO frequency range, it can operate with
even lower LO frequencies to support 1200MHz to
1700MHz low-side LO injection architectures. However,
performance degrades as f
Contact the factory for a variant with increased low-side
LO performance.
The RF input ports for both the main and diversity chan-
nels are internally matched to 50I, requiring no exter-
nal matching components when operating the device
over a 1200MHz to 1700MHz RF frequency range.
A DC-blocking capacitor is required as the input is
internally DC shorted to ground through the on-chip
balun. The RF port input return loss is typically better
than 15dB over the 1200MHz to 1700MHz RF frequency
range.
The RF inputs of the device can also be matched to
operate over an extended 1700MHz to 2000MHz RF
frequency range of with the addition of two shunt 4.7nH
inductors. See Table 1 for details.
The device is optimized for a 1450MHz to 2050MHz
LO frequency range. As an added feature, the device
includes an internal LO SPDT switch for use in frequency-
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 switched in.
LO switching time is typically 50ns, which is more than
adequate for typical GSM applications. If frequency hop-
ping is not employed, simply set the switch to either of
the LO inputs. The switch is controlled by a digital input
(LOSEL), where logic-high selects LO1 and logic-low
selects LO2. LO1 and LO2 inputs are internally matched
to 50I, requiring only 39pF DC-blocking capacitors.
If LOSEL is connected directly to a logic source, then
voltage MUST be applied to V
is applied to LOSEL to avoid damaging the part.
Alternatively, a 1kI resistor can be placed in series at
the LOSEL to limit the input current in applications where
LOSEL is applied before V
The main and diversity channels incorporate a two-stage
LO buffer that allows for a wide-input power range for
the LO drive. The on-chip low-loss baluns, along with LO
buffers, drive the double-balanced mixers. All interfacing
24
LO Inputs, Buffer, and Balun
CC
LO
.
continues to decrease.
CC
RF Port and Balun
before digital logic
and matching components from the LO inputs to the IF
outputs are integrated on-chip.
The core of the MAX19994A dual-channel downconvert-
er consists of two double-balanced, high-performance
passive mixers. Exceptional linearity is provided by the
large LO swing from the on-chip LO buffers. When com-
bined with the integrated IF amplifiers, the cascaded
IIP3, 2LO - 2RF rejection, and noise-figure performance
are typically +25dBm, 68dBc, and 9.8dB, respectively.
The device has a 50MHz to 500MHz IF frequency range,
where the low-end frequency depends on the frequency
response of the external IF components. Note that these
differential ports are ideal for providing enhanced IIP2
performance. Single-ended IF applications require a
4:1 (impedance ratio) balun to transform the 200I dif-
ferential IF impedance to a 50I single-ended system.
After the balun, the return loss is typically 13dB. The user
can use a differential IF amplifier on the mixer IF ports,
but a DC block is required on both IFD+/IFD- and IFM+/
IFM- ports to keep external DC from entering the IF ports
of the mixer.
The RF and LO inputs are internally matched to
50I when operating over 1200MHz to 1700MHz and
1450MHz to 2050MHz frequency ranges, respectively.
No matching components are required for operation
within these bands. The RF port input return loss is
typically better than 15dB over the 1200MHz to 1700MHz
RF frequency range and return loss at the LO ports is
typically better than 15dB over the entire LO range. RF
and LO inputs require only DC-blocking capacitors for
interfacing.
If operating the device over the Extended RF Band of
1700MHz to 2000MHz, simply change the DC-blocking
capacitors to 1.8pF and add a shunt 4.7nH inductor to
each RF port. See Table 1 for details. When matched with
this alternative set of elements, the RF port input return
loss is typically better than 14dB over the 1700MHz to
2000MHz band.
The IF output impedance is 200I (differential). For evalu-
ation, an external low-loss 4:1 (impedance ratio) balun
transforms this impedance to a 50I single-ended output
(see the Typical Application Circuit).
Applications Information
Input and Output Matching
High-Linearity Mixer
Differential IF