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R O C E D U R E
1. Introduction
This document describes the test procedures for the Si4831/35/36/20/24/25-DEMO AM/FM/SW tuner board. It is
also intended to enable customers to exactly replicate Silicon Laboratories’ test environment so that variances in
customers’ and Silicon Laboratories’ measured results can be accurately compared. This document covers FM,
AM, and SW tests for the Si4831/20 and Si4835/36/24/25 receiver.
The Si4831/35/36/20/24/25-DEMO board provides a platform to test and operate the Si4831/35/36/20/24/25 tuner.
Refer to the Si4831/35/36/20/24/25 DEMO Board User's Guide for the operation details of the demo board.
2. FM Tuner Testing Setup
2.1. FM Common Setup
FM tuner standard configuration:
exactly to 98.0 MHz; see the Si4831/35/36/20/24/25 DEMO Board User's Guide for details.
Set volume to maximum unless otherwise specified.
Ensure cable length between the generator and antenna input is as short as possible.
Tune
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Figure 1. FM Tuner Setup with One Generator
Rev. 0.3 2/13
Copyright © 2013 by Silicon Laboratories
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Figure 2. FM Tuner Setup with Two Generators
FM tuner test equipment lists:
& Schwarz UPL Audio Analyzer.
Rohde &Schwarz SML01 Signal Generator
Mini-Circuits Power Combiner
Rohde
2.2. FM Tuner Testing Considerations
Several issues must be considered to make accurate measurements.
First, the power combiner and cable losses must be calibrated and factored into each measurement. The loss for
the Mini-Circuit power combiner is approximately 6 dB.
Second, most signal generators display the voltage generated at the input of the device under test (DUT),
assuming an input resistance of 50
.
For example, if the signal generator displays VL = 1
μV
(0 dBμV), the
generator source voltage VS is 2
μV
(6 dBμV). The load voltage VL is generated from the source voltage VS by the
voltage divider created by the 50
generator source resistance RS and the 50
load resistance RL. This
distinction is important only for sensitivity, and IP3, which are specified in
μV
EMF*, where EMF refers to the source
voltage VS. Measurements such as AM suppression, selectivity, and spurious response are relative and may be
referenced using VS or VL. To summarize, the generator displays the voltage at the input of the DUT. Input
impedance for the Si4831/35/36/20/24/25 FM tuner is high, so to convert the value displayed on the signal
generator to EMF, double the voltage (add 6 dB).
*Note:
EMF = Electro Motive Force
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Rev. 0.3
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3. FM Testing Procedure
3.1. FM Tuning Frequency Range
3.1.1. Description
The test checks the lowest possible tuning frequency and the highest possible tuning frequency of Si4831/35/36/
20/24/25 FM receiver.
3.1.2. Conditions/Procedure
1. Connect test equipment as shown in Figure 1.
2. Configure the tuner in standard configuration.
3. Configure the audio analyzer:
a. Select Analyze.
b. Set Function = THD+N/SINAD.
i. Set Measurement Mode = SINAD.
ii. Set Unit = dB.
iii. Set Filter = A-weighting.
iv. Set Frequency Limit Low = 300 Hz.
v. Set Frequency Limit High = 15000 Hz.
4. Configure generator:
a. Set RF level = 0 dBμV.
b. Select FM Modulation.
i. Set FM Deviation = 22.5 kHz.
ii. Set source = LFGEN.
iii. Set LFGEN frequency = 1 kHz.
c. Enable modulation.
d. Enable carrier.
5. Slide band switch to select FM1 band for testing.
6. Turn tuning wheel to the lowest possible position.
7. Adjust signal generator RF (by 10 kHz step), until the measured SINAD reaches maximum level. Record
this RF frequency as the lowest tuning frequency Fmin.
8. Repeat for highest tuning frequency point Fmax.
9. Repeat for other FM band testing.
3.1.3. Pass Criteria
The FM tuning frequency range should be the FM band frequency range. Refer to the Si4831/35/36/20/24/25
DEMO Board User's Guide.
Rev. 0.3
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3.2. FM Sensitivity
3.2.1. Description
Determine input level in dBµVemf to result in 26 dB SINAD in mono RX mode.
3.2.2. Conditions/Procedure
1. Connect test equipment as shown in Figure 1.
2. Configure the tuner in standard configuration.
3. Configure the audio analyzer:
a. Select Analyze.
b. Set Function = THD+N/SINAD.
i. Set Measurement Mode = SINAD.
ii. Set Unit = dB.
iii. Set Filter = A-weighting.
iv. Set Frequency Limit Low = 300 Hz.
v. Set Frequency Limit High = 15000 Hz.
4. Configure generator:
a. Set carrier frequency = 98 MHz.
b. Select FM Modulation.
i. Set FM Deviation = 22.5 kHz.
ii. Set Source = LFGEN.
iii. Set LFGEN frequency = 1 kHz.
c. Enable modulation.
d. Enable carrier.
5. Adjust generator RF level, VRF0, until audio analyzer SINAD = 26 dB ±1 dB.
6. Sensitivity (dBμVemf) = VRF0.
3.2.3. Pass Criteria
FM sensitivity should be below 10 dBµVemf.
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Rev. 0.3
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3.3. FM Image Rejection
3.3.1. Description
The test measures the FM image rejection of the tuner.
3.3.2. Conditions/Procedure
1. Connect test equipment as shown in Figure 1.
2. Configure the tuner in standard configuration.
3. Configure the audio analyzer:
a. Select Analyze.
b. Set Function = THD+N/SINAD.
i. Set Measurement Mode = SINAD.
ii. Set Unit = dB.
iii. Set Filter = A-weighting.
iv. Set Frequency Limit Low = 300 Hz.
v. Set Frequency Limit High = 15000 Hz.
4. Configure generator:
a. Set carrier frequency = 98 MHz.
b. Select FM Modulation.
i. Set FM Deviation = 22.5 kHz.
ii. Set Source = LFGEN.
iii. Set LFGEN frequency = 1 kHz.
c. Enable modulation.
d. Enable carrier.
5. Adjust generator RF level, VRF1, until audio analyzer SINAD = 26 dB ±1 dB.
6. Record the RF level = VRF1.
7. Change generator carrier frequency to 97.744 MHz
8. Adjust generator RF level*, VRF2, until audio analyzer SINAD = 26 dB ±1 dB.
9. Image rejection (dB) = VRF2 – VRF1.
Note:
Maximum RF level setting for the R&S SML01 signal generator is 120 dBμV. You cannot increase the RF level beyond
this value. If you adjust generator RF level from VRF1 to 120 dBμV, the audio analyzer SINAD still can not get to the
SINAD = 26 dB ±1 dB, and your image rejection will be better than 120 dBμV – VRF1.
3.3.3. Pass Criteria
FM Image rejection should be more than 40 dB.
Rev. 0.3
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