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Changing the Gain

3-4

3.5 Changing the Gain

The APA100 EVM is set with a gain of 31.4 dB, but can be adjusted. The

front-end has a gain of 4.4 dB (−1.667 V/V), and a back-end gain of 27 dB

(−22.4 V/V), for a total of 31.4 dB (37.3 V/V). The back-end gain needs to be

kept constant, because it is set by the control-loop feedback system with the

TLV2464A, TPA2001D1, and TAS5111. The front-end gain is set by section A

of the quad operational amplifier TLV2464A. The front-end gain is set by

Equation 1, which is a ratio of feedback to input resistors.

Front−end Gain +*

(R5 ) R6)

(VńV)

(1)

The APA100 EVM total gain can then be set by multiplying the front-end and

back-end gains, as shown in Equation 2.

(2)

Total Gain + 22.4

(R5 ) R6)

(VńV)

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Texas Instruments APA100 Manuale Utente Pagina 22