SI4721 datasheet(13/68 Pages) SILABS

Part #	SI4721

Description	Si470X/1X/2X/3X/4X EVALUATION BOARD TEST PROCEDURE

PDF	68 Pages

Scroll/Zoom	100%

Manufacturer	SILABS [Silicon Laboratories]

Direct Link	http://www.silabs.com

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13 / 68 page

AN388

Rev. 0.2

2.3.2. THD

The total harmonic distortion, or THD, is a measurement of the harmonic distortion present at the audio output and

is defined as the ratio of the sum of the powers of all harmonic components calculated in RMS fashion to the power

of the fundamental.

1. Connect test equipment as shown in Figures 1, 2, or 3.

2. Configure the tuner in standard configuration.

3. Configure the audio analyzer:

a. Select Analyze.

b. Set Function = THD.

Set Measurement Mode = All di (all harmonics).

ii. Select Unit = %.

4. Configure generator #1:

a. Set carrier frequency = 98.1 MHz.

b. Select FM Modulation.

Set FM Deviation = 75 kHz.

ii. Set RF level = 60 dBµV.

iii. Set source = LFGEN.

iv. Set LFGEN frequency = 1 kHz.

c. Enable modulation.

d. Enable carrier.

5. Disable generator #2.

6. Record THD (%).

SI4721 Datasheet(PDF) 13 Page - Silicon Laboratories