TQ9203 데이터 시트보기 (PDF) - TriQuint Semiconductor
부품명
상세내역
제조사
TQ9203 Datasheet PDF : 12 Pages
| |||
TQ9203 Product Description
The TQ9203 efficiently integrates a low-noise amplifier and
high-intercept mixer, with performance equal to a discrete
implementation, though use of circuit techniques from monolithic
and discrete design practices. The LNA consists of two
cascaded common-source amplifier stages, using a “DC-
stacked”topology, in which the same DC current flows through
both stages. An external noise match is used to achieve
optimum noise figure. Matching is performed with PC board
microstrip lines or lumped-elements surface-mount components,
using simple, well understood networks. The output on-chip
impedance is matched to 50 ohms.
The mixer is implemented as a “cascode”stage operating like a
dual-gate FET mixer. A common-gate LO buffer provides the
necessary gain to drive the mixer FET gate and establishes a
good input match. The on-chip buffer amplifier allows for direct
connection to a commercial VCO at drive levels down to –6dBm.
An “open collector”IF output allows for flexibility, matching to
various Ifs and filter types.
The two topologies efficiently use the supply current for low-
power operation, approximately 10mA with a 5V supply. The
overall circuit provides a distinct performance edge over silicon
monolithic designs in terms of input intercept, noise figure and
gain. Specifically, the circuit was intended for use in the
following applications: cellular (AMPS, NADC, GSM, JDC,
ETACS, etc.) and ISM band (902 – 928MHz).
In addition, two selectable LNA inputs are available. They are
implemented through the use of two independent first stages,
each connected to the second-stage input. A SELECT pin
controls which input is active by steering the current through the
selected input stage and cutting it off from the other. This
provides the optional functionality of a diversity switch in front of
the LNA, but without the insertion loss and noise figure penalty
from the switch.
Operation
Please refer to the test circuit above.
TQ9203
Data Sheet
Power Supply Connection
The TQ9203 was designed to operate within specifications over
the power supply range of 4.5 to 5.5V, although it will function
over a range of 4.0 to 6.0V. The internal biasing maintains
stable operating points with varying supply voltage. However,
the electrical parameters do vary slightly with supply voltage.
Internally, the downconverter has 50pF of capacitance from Vdd
to ground for RF decoupling of the supply line. This should be
augmented with additional decoupling capacitance: 1000pF
connected externally within 5mm of the package pin. A 10-ohm
series resistor in the Vdd line may also be added (optionally) to
provide some filtering of supply line noise. Connections to
ground should go directly to a low-impedance ground plane.
Therefore, it is recommended that multiple via holes to the
ground plane occur within 2mm on the inside of the package
pins.
LNA Input Interfacing
The TQ9203 LNA was designed for low-noise operation. It
makes use of an optimum noise-matching network at the input,
not a conjugate match, as would be used for maximum power
transfer (although gamma optimum is near the conjugate
match). Gamma optimum is referenced from the LNA input into
the noise-match network in series with 50 ohms. The gamma
optimum and the noise parameters for selected frequencies are
shown in the LNA Noise Parameters table.
There are several options for the physical realization of gamma
optimum: a series-shunt microstrip transmission line network, a
series capacitor/shunt inductor, and a series inductor. Ideal
values for these components are included in the Noise
Parameters table. The microstrip transmission lines can easily
be constructed on FR-4 or G-10 circuit boards, using standard
design techniques. The lumped-element components are
surface-mount elements designed for RF use. Slight
adjustments in the actual values of the elements are likely, due
to the effects of component parasitics. It is important that the
board-level circuit establishes an impedance of gamma
optimum, measure at the solder pad of pin 6. Proper board
design for gamma optimum eliminates the need for tuning
adjustments and produces a low-noise circuit, which is tolerant
of component variations.
For additional information and latest specifications, see our website: www.triquint.com
9
Share Link: 