The MAX19995A dual-channel downconverter is
designed to provide 8.7dB of conversion gain,
+24.8dBm input IP3, +13.5dBm 1dB input compression
point, and a noise figure of 9.2dB for 1700MHz to
2200MHz diversity receiver applications. With an optimized LO frequency range of 1750MHz to 2700MHz, this
mixer is ideal for high-side LO injection architectures.
Low-side LO injection is supported by the MAX19995,
which is pin-pin and functionally compatible with the
MAX19995A.
In addition to offering excellent linearity and noise performance, the MAX19995A also yields a high level of
component integration. This device includes two doublebalanced passive mixer cores, two LO buffers, a dualinput LO selectable switch, and a pair of differential IF
output amplifiers. Integrated on-chip baluns allow for single-ended RF and LO inputs. The MAX19995A requires a
nominal LO drive of 0dBm and a typical supply current of
350mA at V
CC
= 5.0V, or 242mA at VCC= 3.3V.
The MAX19995/MAX19995A are pin compatible with the
MAX19985/MAX19985A series of 700MHz to 1000MHz
mixers and pin similar to the MAX19997A/MAX19999
series of 1800MHz to 4000MHz mixers, making this
entire family of downconverters ideal for applications
where a common PCB layout is used across multiple
frequency bands.
The MAX19995A is available in a 6mm x 6mm, 36-pin
thin QFN package with an exposed pad. Electrical performance is guaranteed over the extended temperature
range (TC= -40°C to +85°C).
Applications
UMTS/WCDMA Base Stations
LTE/WiMAX™Base Stations
TD-SCDMA Base Stations
DCS1800/PCS1900 and GSM/EDGE Base
Stations
cdma2000
®
Base Stations
Fixed Broadband Wireless Access
Wireless Local Loop
Private Mobile Radios
Military Systems
Features
♦ 1700MHz to 2200MHz RF Frequency Range
♦ 1750MHz to 2700MHz LO Frequency Range
♦ 50MHz to 500MHz IF Frequency Range
♦ 8.7dB Typical Conversion Gain
♦ 9.2dB Typical Noise Figure
♦ +24.8dBm Typical Input IP3
♦ +13.5dBm Typical Input 1dB Compression Point
♦ 64dBc Typical 2LO-2RF Spurious Rejection at
P
RF
= -10dBm
♦ Dual Channels Ideal for Diversity Receiver
Applications
♦ 48dB Typical Channel-to-Channel Isolation
♦ Low -3dBm to +3dBm LO Drive
♦ Integrated LO Buffer
♦ Internal RF and LO Baluns for Single-Ended
Inputs
♦ Built-In SPDT LO Switch with 48dB LO-to-LO
Isolation and 50ns Switching Time
♦ Pin Compatible with the MAX19985/MAX19985A/
MAX19995 Series of 700MHz to 2200MHz Mixers
♦ Pin Similar to the MAX19997A/MAX19999 Series
of 1800MHz to 4000MHz Mixers
♦ Single 5.0V or 3.3V Supply
♦ External Current-Setting Resistors Provide Option
for Operating Device in Reduced-Power/ReducedPerformance Mode
, VCC= 4.75V to 5.25V, no input AC signals. TC= -40°C to +85°C, R1 = R4 = 681Ω, R2 = R5 = 1.5kΩ.
Typical values are at V
CC
= 5.0V, TC= +25°C, unless otherwise noted. All parameters are production tested.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Note 1: Based on junction temperature TJ= TC+ (θJCx VCCx ICC). This formula can be used when the temperature of the exposed
pad is known while the device is soldered down to a PCB. See the
Applications Information
section for details. The junction
temperature must not exceed +150°C.
Note 2: Junction temperature T
J
= TA+ (θJAx VCCx ICC). This formula can be used when the ambient temperature of the PCB is
known. The junction temperature must not exceed +150°C.
Note 3: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial
.
Note 4: T
C
is the temperature on the exposed pad of the package. TAis the ambient temperature of the device and PCB.
V
CC
to GND...........................................................-0.3V to +5.5V
LO1, LO2 to GND ..................................................-0.3V to +0.3V
LOSEL to GND ...........................................-0.3V to (V
CC
+ 0.3V)
RFMAIN, RFDIV, and LO_ Input Power ..........................+15dBm
RFMAIN, RFDIV Current (RF is DC shorted to GND
through a balun)..............................................................50mA
Continuous Power Dissipation (Note 1) ...............................8.7W
All parameters are guaranteed by design and characterization, unless otherwise noted.) (Note 6)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
RF Frequencyf
LO Frequencyf
IF Frequencyf
LO Drive LevelP
RF
LO
IF
LO
(Note 5)17002200MHz
(Note 5)17502700MHz
U si ng M i ni - C i r cui ts TC 4- 1W- 17 4:1
tr ansfor m er as d efi ned i n the Typ i cal Ap p l i cati on C i r cui t, IF m atchi ng com p onents
affect the IF fr eq uency r ang e ( N ote 5)
U si ng al ter nati ve M i ni - C i r cui ts TC 4- 1W- 7A
4:1 tr ansfor m er as d efi ned i n the Typ i cal Ap p l i cati on C i r cui t, IF m atchi ng com p onents
affect the IF fr eq uency r ang e ( N ote 5)
100500
50250
-3+3dBm
Conversion GainG
Conversion Gain FlatnessΔG
Gain Variation Over TemperatureTC
Input Compression PointIP
Input Third-Order Intercept PointIIP3
Input Third-Order Intercept Point
Variation Over Temperature
Note 5:Not production tested. Operation outside this range is possible, but with degraded performance of some parameters.
See the
Typical Operating Characteristics
.
Note 6:All limits reflect losses of external components, including a 0.9dB loss at f
IF
= 350MHz due to the 4:1 transformer. Output
measurements were taken at IF outputs of the
Typical Application Circuit
.
Note 7:100% production tested.
Note 8:100% production tested for functionality.
Note 9:Maximum reliable continuous input power applied to the RF or IF port of this device is +12dBm from a 50Ω source.
Note 10: Not production tested.
Note 11: Measured with external LO source noise filtered so the noise floor is -174dBm/Hz. This specification reflects the effects of
all SNR degradations in the mixer, including the LO noise as defined in Application Note 2021:
Specifications and
Measurement of Local Oscillator Noise in Integrated Circuit Base Station Mixers
.
LO Input Return Loss
IF Output Return Loss
RF-to-IF Isolation36dB
LO Leakage at RF Port-40dBm
2LO Leakage at RF Port-23dBm
LO Leakage at IF Port-37dBm
Channel Isolation
LO-to-LO Isolation
LO Switching Time50% of LOSEL to IF settled within 2 degrees50ns
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
LO port selected, RF and IF terminated into
matched impedance
LO port unselected, RF and IF terminated
into matched impedance
RF terminated into 50Ω, LO driven by 50Ω
source, IF transformed to 50Ω using
external components shown in the Typical
Application Circuit
RFMAIN converted power measured at
IFDIV relative to IFMAIN, all unused ports
terminated to 50Ω
RFDIV converted power measured at
IFMAIN relative to IFDIV, all unused ports
terminated to 50Ω
1RFMAINMain Channel RF input. Internally matched to 50Ω. Requires an input DC-blocking capacitor.
2TAPMAIN
3, 5, 7, 12,
20, 22, 24,
25, 26, 34
GNDGround
Main Channel Balun Center Tap. Bypass to GND with 39pF and 0.033µF capacitors as close as
possible to the pin with the smaller value capacitor closer to the part.
4, 6, 10, 16,
21, 30, 36
8TAPDIV
9RFDIVDiversity Channel RF input. Internally matched to 50Ω. Requires an input DC-blocking capacitor.
11IFD_SET
13, 14IFD+, IFD-
15IND_EXTD
17LO_ADJ_D
18, 28N.C.No Connection. Not internally connected.
19LO1Local Osci l l ator 1 Inp ut. Thi s i np ut i s i nter nal l y m atched to 50Ω . Req ui r es an i np ut D C - b l ocki ng cap aci tor .
23LOSELLocal Oscillator Select. Set this pin to high to select LO1. Set to low to select LO2.
27LO2Local Osci l l ator 2 Inp ut. Thi s i np ut i s i nter nal l y m atched to 50Ω . Req ui r es an i np ut D C - b l ocki ng cap aci tor .
29LO_ADJ_M
31IND_EXTM
V
CC
Power Supply. Bypass to GND with capacitors as shown in the Typical Application Circuit as close as
possible to the pin.
Diversity Channel Balun Center Tap. Bypass to GND with 39pF and 0.033µF capacitors as close as
possible to the pin with the smaller value capacitor closer to the part.
IF Diversity Amplifier Bias Control. Connect a resistor from this pin to ground to set the bias current for
the diversity IF amplifier (see the Typical Operating Characteristics for typical performance vs.
resistor value).
Diversity Mixer Differential IF Output. Connect pullup inductors from each of these pins to V
the Typical Application Circuit).
Diversity External Inductor Connection. Connect this pin to ground. For improved RF-to-IF and LO-toIF isolation, connect a low-ESR 10nH inductor from this pin to ground (see the Typical OperatingCharacteristics for typical performance vs. inductor value).
LO Diversity Amplifier Bias Control. Connect a resistor from this pin to ground to set the bias current
for the diversity LO amplifier (see the Typical Operating Characteristics for typical performance vs.
resistor value).
LO M ai n Am p l i fi er Bi as C ontr ol . C onnect a r esi stor fr om thi s p i n to g r ound to set the b i as cur r ent for the
m ai n LO am p l i fi er ( see the Typical Operating Characteristics for typ i cal p er for m ance vs. r esi stor val ue) .
Main External Inductor Connection. Connect this pin to ground. For improved RF-to-IF and LO-to-IF
isolation, connect a low-ESR 10nH inductor from this pin to ground (see the Typical OperatingCharacteristics for typical performance vs. inductor value).
CC
(see
32, 33IFM-, IFM+
35IFM_SET
—EP
Main Mixer Differential IF Output. Connect pullup inductors from each of these pins to V
Typical Application Circuit).
IF M ai n Am p l i fi er Bi as C ontr ol . C onnect a r esi stor fr om thi s p i n to g r ound to set the b i as cur r ent for the
m ai n IF am p l i fi er ( see the Typical Operating Characteristics for typ i cal p er for m ance vs. r esi stor val ue) .
Exposed Pad. Internally connected to GND. Solder this exposed pad to a PCB pad that uses multiple
ground vias to provide heat transfer out of the device into the PCB ground planes. These multiple
ground vias are also required to achieve the noted RF performance.
(see the
CC
Detailed Description
The MAX19995A is a dual-channel downconverter
designed to provide up to 8.7dB of conversion gain,
+24.8dBm input IP3, +13.5dBm 1dB input compression
point, and a noise figure as low as 9.2dB.
In addition to its high-linearity performance, the
MAX19995A achieves a high level of component integration. The device integrates two double-balanced
mixers for two-channel downconversion. Both the main
and diversity channels include a balun and matching
circuitry to allow 50Ω single-ended interfaces to the RF
ports and the two LO ports. An integrated singlepole/double-throw (SPDT) switch provides 50ns switching time between the two LO inputs, with 48dB of
LO-to-LO isolation and -35dBm of LO leakage at the RF
port. Furthermore, the integrated LO buffers provide a
high drive level to each mixer core, reducing the LO
drive required at the MAX19995A’s inputs to a range of
-3dBm to +3dBm. The IF ports for both channels incorporate differential outputs for downconversion, which
are ideal for providing enhanced 2LO-2RF performance.
Specifications are guaranteed over broad frequency
ranges to allow for use in UMTS/WCDMA, LTE/WiMAX,
DCS1800/PCS1900 GSM/EDGE, TD-SCDMA, and
cdma2000 base stations. The MAX19995A is specified
to operate over an RF input range of 1700MHz to
2200MHz, an LO range of 1750MHz to 2700MHz, and
an IF range of 50MHz to 500MHz. The external IF components set the lower frequency range (see the
Typical
Operating Characteristics
for details). Operation
beyond these ranges is possible; see the
Typical
Operating Characteristics
for additional information.
Although this device is optimized for high-side LO
injection applications, it can operate in low-side LO
injection modes as well. However, performance
degrades as f
LO
continues to decrease. For increased
low-side LO performance, refer to the MAX19995 data
sheet.
RF Port and Balun
The RF input ports of both the main and diversity channels are internally matched to 50Ω, requiring no external matching components. 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 16.5dB over the RF frequency
range of 1700MHz to 2200MHz.
LO Inputs, Buffer, and Balun
The MAX19995A is optimized for a 1750MHz to
2700MHz LO frequency range. As an added feature,
the MAX19995A 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 hopping 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 50Ω, requiring
only 39pF DC-blocking capacitors.
If LOSEL is connected directly to a logic source, then
voltage MUST be applied to V
CC
before digital logic is
applied to LOSEL to avoid damaging the part.
Alternatively, a 1kΩ resistor can be placed in series at
the LOSEL to limit the input current in applications
where LOSEL is applied before VCC.
The main and diversity channels incorporate a twostage 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 and matching components from the
LO inputs to the IF outputs are integrated on-chip.
High-Linearity Mixer
The core of the MAX19995A dual-channel downconverter 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 combined with the integrated IF amplifiers, the
cascaded IIP3, 2LO-2RF rejection, and noise-figure
performance are typically +24.8dBm, 64dBc, and
9.2dB, respectively.
Differential IF
The MAX19995A has an IF frequency range of 50MHz
to 500MHz, 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 200Ω differential IF impedance to a 50Ω singleended system. After the balun, the return loss is typically 11.5dB. 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 50Ω.
No matching components are required. The RF port
input return loss is typically better than 16.5dB over the
RF frequency range of 1700MHz to 2200MHz 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.
The IF output impedance is 200Ω (differential). For
evaluation, an external low-loss 4:1 (impedance ratio)
balun transforms this impedance to a 50Ω single-ended
output (see the
Typical Application Circuit
).
Reduced-Power Mode
Each channel of the MAX19995A has two pins
(LO_ADJ_ _, IF_ _SET) that allow external resistors to
set the internal bias currents. Nominal values for these
resistors are given in Table 1. Larger value resistors
can be used to reduce power dissipation at the
expense of some performance loss. If ±1% resistors
are not readily available, substitute with ±5% resistors.
Significant reductions in power consumption can also
be realized by operating the mixer with an optional supply voltage of 3.3V. Doing so reduces the overall power
consumption by up to 54%. See the
3.3V Supply AC
Electrical Characteristics
table and the relevant 3.3V
curves in the
Typical Operating Characteristics
section.
IND_EXT_ Inductors
For applications requiring optimum RF-to-IF and LO-toIF isolation, connect low-ESR inductors from IND_EXT_
(pins 15 and 31) to ground. When improved isolation is
not required, connect IND_EXT_ to ground using 0Ω
resistance. See the
Typical Operating Characteristics
to
evaluate the isolation vs. inductor value tradeoff.
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.
The load impedance presented to the mixer must be so
that any capacitance from both IF- and IF+ to ground
does not exceed several picofarads. 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-conduction path
for the device. Solder the exposed pad on the bottom
of the device package to the PCB. The MAX19995A
evaluation kit can be used as a reference for board layout. Gerber files are available upon request at
www.maxim-ic.com
.
Power-Supply Bypassing
Proper voltage-supply bypassing is essential for highfrequency circuit stability. Bypass each VCCpin and
TAPMAIN/TAPDIV with the capacitors shown in the
Typical Application Circuit
(see Table 1 for component
values). Place the TAPMAIN/TAPDIV bypass capacitors
to ground within 100 mils of the pin.
Exposed Pad RF/Thermal Considerations
The exposed pad (EP) of the MAX19995A’s 36-pin thin
QFN-EP package provides a low thermal-resistance
path to the die. It is important that the PCB on which the
MAX19995A is mounted be designed to conduct heat
from the EP. In addition, provide the EP with a lowinductance path to electrical ground. The EP MUST be
soldered to a ground plane on the PCB, either directly
or through an array of plated via holes.
U11MAX19995A IC (36 TQFN-EP)Maxim Integrated Products, Inc.
639pF microwave capacitors (0402)Murata Electronics North America, Inc.
50.01µF microwave capacitors (0402)Murata Electronics North America, Inc.
6150pF microwave capacitors (0603)Murata Electronics North America, Inc.
10nH wire-wound high-Q inductors (0603). Smaller values can
be used at the expense of some performance loss (see the
Typical Operating Characteristics).
681Ω ±1% resistors (0402). Used for VCC = 5.0V applications.
Larger values can be used to reduce power at the expense of
some performance loss (see the Typical OperatingCharacteristics).
909Ω ±1% resistors (0402). Used for V
1.5kΩ ±1% resistors (0402). Used for VCC = 5.0V applications.
Larger values can be used to reduce power at the expense of
some performance loss (see the Typical OperatingCharacteristics).
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________