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© Koninklijke Philips Electronics N.V. 2004. All rights reserved.

Objective data sheet

Rev. 01 — 1 November 2004

9 of 16

Philips Semiconductors

SA58640

Low-voltage mixer FM IF system

13. Test information

The following list items 1 through 8 apply to Figure 4:

1. The C-message and de-emphasis filter combination has a peak gain of 10 for

accurate measurements. Without the gain, the measurements may be affected by the

noise of the scope and HP339A analyzer. The de-emphasis filter has a fixed

6 dB/Octave slope between 300 Hz and 3 kHz.

2. The ceramic filters can be 30 kHz SFG455A3s made by Murata which have 30 kHz IF

bandwidth (they come in blue), or 16 kHz CFU455Ds, also made by Murata (they

come in black). All specifications and testing are done with the wideband filter.

3. Set your RF generator at 45.000 MHz, use a 1 kHz modulation frequency and a 6 kHz

deviation if you use 16 kHz filters, or 8 kHz if you use 30 kHz filters.

4. The measured typical sensitivity for 12 dB SINAD should be 0.45

PV or 114 dBm at

the RF input.

5. The layout is very critical in the performance of the receiver. We highly recommend

our demo board layout.

6. The smallest RSSI voltage (i.e., when no RF input is present and the input is

terminated) is a measure of the quality of the layout and design. If the lowest RSSI

voltage is 500 mV or higher, it means the receiver is in regenerative mode. In that

case, the receiver sensitivity will be worse than expected.

7. All of the inductors, the quad tank, and their shield must be grounded. A 10

PF to

15

PF or higher value tantalum capacitor on the supply line is essential. A low

frequency ESR screening test on this capacitor will ensure consistent good sensitivity

in production. A 0.1

PF bypass capacitor on the supply pin, and grounded near the

44.545 MHz oscillator improves sensitivity by 2 dB to 3 dB.

8. R5 can be used to bias the oscillator transistor at a higher current for operation above

45 MHz. Recommended value is 22 k

:, but should not be below 10 k:.

Fig 4.

Application circuit test setup

SCOPE

SA58640 DEMOBOARD

RSSI

AUDIO

002aab127

RF GENERATOR

45 MHz

DC VOLTMETER

HP339A DISTORTION

ANALYZER

C–MESSAGE

DE-EMPHASIS

FILTER