TAT2814A 查看數據表（PDF） - TriQuint Semiconductor
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TAT2814A Datasheet PDF : 11 Pages
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TAT2814A
DOCSIS 3.0 / Edge QAM Variable Gain Amplifier
Detailed Device Description
Balance
The TAT2814A is designed for excellent differential-mode performance throughout the chain. Unlike many commercially
available push-pull amplifiers built with 2 discrete die, both stages of the TAT2814A are single-chip designs utilizing a
differential pair topology for best common-mode performance. Provision is made for using external bias inductors to increase
tail impedances in the input differential pairs, improving further the signal balance and 2nd order performance through the
chain. The RF output of the first stage is connected internally to the differential attenuator and brought out to external pins for
applying stage bias and enabling RF feedback to the input. The attenuator outputs are brought out to a single side of the
TAT2814A for customers desiring to perform inter-stage filtering or signal processing. The differential inputs to the output
stage are located on an adjacent side of the die, spaced to minimize package coupling so as to not limit the performance of off-
stage filtering.
Input Matching
The input stage is designed to have 75 Ω differential impedance. However, provision is made for shunt feedback to be easily
applied to lower the input impedance to best match to 50 Ω. The external shunt feedback easily allows customers to optimize
the input impedance to control DAC anomalies. The bias current of the input stage may be adjusted with an external resistor to
ground.
Pre-Amp Powerdown
The preamp stage of the TAT2814A can be powered down by setting PD pin to Logic LOW. VDD pins should be set to 5 V in
both power-down and operating modes.
Gain Adjustment
A fully differential gain control function is implemented with a low distortion analog diode-based attenuator. The attenuator
provides for monotonic gain adjustment over a full 19 dB attenuation range. The excellent RF match characteristics ensure
excellent gain flatness and return loss over the full attenuation range. Control is provided by a single current controlled line.
Attenuation is monotonic and linear with control current.
Output Stage
A differential output stage has excellent output linearity performance at very low power. The differential outputs of the second
stage may be combined with a commercially available balun to provide for single-ended drive signals. For best performance
the bias current of the output stage may be placed in active bias control. This is implemented by sensing the voltage at pin 19
and providing a feedback voltage bias to pin 27. Please contact TriQuint for further details.
Thermal Management
Total power consumption of the TAT2814A is less than 5 Watts. Care must be taken in the layout to provide adequate thermal
path with multiple vias under the TAT2814A. A heat sink should also be used to carry heat away from the backside PCB.
Technology
The TAT2814A utilizes proven pHEMT device technology that has yielded over 200 million RFICs to date. For detailed
qualification and reliability reports on other products fabricated in this process, please consult TriQuint. Key RFICs that will
be used in the TAT2814A have already exceeded industry qualification requirements in other packages.
Bias Current Set
Bias current to each amplification stage is set by external circuitry to allow trade-off of power consumption and distortion
performance.
Separate Bias Voltage for each stage
Preamplifier, interstage attenuator, and driver amplifier have independent voltage supply pins.
Data Sheet: Rev D 05-03-12
© 2012 TriQuint Semiconductor, Inc.
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Disclaimer: Subject to change without noticee
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