T E C H N I C A L I N F O R M A T I O N
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To maximize the damping factor and reduce distortion and noise, the modulator feedback
connections should be routed directly to the pins of the output inductors. LO. Please refer
to the EB-TA3020This was done on the EB-TA3020 for additional information.
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The output filter capacitor, CO, and zobel capacitor, CZ, should be star connected with the
load return. The output ground feedback signal should be taken from this star point.
The modulator feedback resistors, RFBA, RFBB, and RFBC, should all be grounded and
attached to 5V together. These connections will serve to minimize common mode noise
via the differential feedback. Please refer to the EB-TA3020 evaluation board for more
information.
TA3020 Grounding
Proper grounding techniques are required to maximize TA3020 functionality and performance.
Parametric parameters such as THD+N, Noise Floor and Crosstalk can be adversely affected if
proper grounding techniques are not implemented on the PCB layout. The following discussion
highlights some recommendations about grounding both with respect to the TA3020 as well as
general “audio system” design rules.
The TA3020 is divided into two sections: the input section, which spans pin 12 through pin 37, and
the output (high voltage) section, which spans pin 1 through pin 10 and pin 39 through pin 48. On
the TA3020 evaluation board, the ground is also divided into distinct sections, one for the input and
one for the output. To minimize ground loops and keep the audio noise floor as low as possible, the
input and output ground must be only connected at a single point. Depending on the system design,
the single point connection may be in the form of a ferrite bead or a PCB trace.
The analog grounds, pin 28 and pin 34 must be connected locally at the TA3020 for proper device
functionality. The ground for the V5 power supply should connect directly to pin 28. Additionally, any
external input circuitry such as preamps, or active filters, should be referenced to pin 28.
For the power section, Tripath has traditionally used a “star” grounding scheme. Thus, the load
ground returns and the power supply decoupling traces are routed separately back to the power
supply. In addition, any type of shield or chassis connection would be connected directly to the
ground star located at the power supply. These precautions will both minimize audible noise and
enhance the crosstalk performance of the TA3020.
The TA3020 incorporates a differential feedback system to minimize the effects of ground bounce
and cancel out common mode ground noise. As such, the feedback from the output ground for each
channel needs to be properly sensed. This can be accomplished by connecting the output ground
“sensing” trace directly to the star formed by the output ground return, output capacitor, CO, and the
zobel capacitor, CZ. Refer to the Application / Test Circuit for a schematic description.
TA3020 Amplifier Gain
The gain of the TA3020 is the product of the input stage gain and the modulator gain. Please refer
to the sections, Input Stage Design, and Modulator Feedback Design, for a complete explanation of
how to determine the external component values.
TA3020, Rev 2.1, 01.01
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TRIPATH [ TRIPATH TECHNOLOGY INC. ]
