max2690 Maxim Integrated Products, Inc., max2690 Datasheet - Page 7

• Manufacturer Part Number: max2690
• Description: Max2690 Low-noise, 2.5ghz Downconverter Mixer
• Manufacturer: Maxim Integrated Products, Inc.

The MAX2690 is a 2.5GHz, double-balanced downcon-
verter mixer designed to provide optimum intermodula-
tion performance for a given supply current. It consists
of a double-balanced Gilbert-cell mixer with single-
ended RF and LO port connections, and a differential
IF port. An on-chip bias cell provides a low-power shut-
down feature.
The RFIN and RFBYP pins form the MAX2690’s RF
input. The single-ended RF input signal is applied to
the RFIN pin (refer to the RF Port Impedance vs.
Frequency graph in the Typical Operating Character-
istics ). The RFBYP pin should be AC grounded typically
with a 1000pF capacitor. This capacitor value should
present a low impedance at both the RF and IF
frequencies.
_______________Detailed Description
______________________________________________________________Pin Description
PIN
10
1
2
3
4
5
6
7
8
9
GNDLO
IFOUT+
IFOUT-
RFBYP
NAME
LGND
SHDN
GND
RFIN
V
LO
CC
_______________________________________________________________________________________
Inductive Degeneration Pin. For maximum linearity, connect LGND directly to ground with no series induc-
tance. Trade off linearity for gain by increasing the series inductance from LGND to ground. See the
Applications Information section for more information.
RF Ground. This pin must have a separate via to the ground plane, as close to the pin as possible to
minimize inductance.
RF Input Port. RF Input of Downconverter Mixer. See the Applications Information section for details on
matching to RFIN.
RF Bypassing Capacitor Pin. Bypass RFBYP with an appropriate-value capacitor (typically 1000pF) to ground.
Supply-Voltage Input, +2.7V to +5.5V. Connect 0.1µF and 1000pF capacitors (in parallel) between V
and GND.
Local-Oscillator Input. LO should be AC coupled and presents a 50Ω load impedance. See the Applications
Information section for more information.
Ground for the LO Port. This pin must have its own via to the ground plane, as close as possible to the pin to
minimize inductance.
Differential IF Inverting Output. IFOUT- is an open-collector output and must be pulled up to V
external inductor for proper biasing. A resistor in parallel with the inductor may also be used to set a termi-
nating impedance. See the Typical Operating Characteristics section for a plot of IF port characteristics vs.
frequency (see plot titled Single-Ended IF Port Equivalent Shunt RC Network).
Differential IF Noninverting Output. IFOUT+ is an open-collector output and must be pulled up to V
an external inductor for proper biasing. A resistor in parallel with the inductor may also be used to set a ter-
minating impedance. See the Typical Operating Characteristics section for a plot of IF port characteristics
vs. frequency (see plot titled Single-Ended IF Port Equivalent Shunt RC Network).
Active-Low Shutdown Input. A digital logic-low level at SHDN deactivates all part functions and reduces the
supply current to typically 0.4µA.
RF Input
The IFOUT+ and IFOUT- pins form the MAX2690’s differ-
ential open-collector IF output. The IF output is coupled to
the load using shunt inductors to V
tors to the load. Most applications use a resistive termina-
tion of 500Ω (typical) resistors in parallel with the pull-up
inductors to set a terminating impedance. The part’s con-
version gain has been specified with the resistors in place
(using the output network on the MAX2690 EV kit),
accounting for a 3dB loss due to the resistors. Therefore,
it is possible to achieve an increase in gain with a proper-
ly designed matching network. However, the resistors
provide for minimum passband ripple when this port is
connected to typical IF filters.
The bias cell includes compensation circuitry to mini-
mize conversion-gain variations over temperature as
well as shutdown control circuitry. The SHDN pin can
be used to disable all functions and reduce supply cur-
rent to typically 0.4µA.
FUNCTION
Downconverter Mixer
Low-Noise, 2.5GHz
CC
and series capaci-
CC
IF Output
with an
CC
CC
with
Bias
7