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FILTERLESS WIDEBAND FM IF DETECTOR
S1A0429A
INTRODUCTION
The S1A0429A is a monolithic integrated circuit designed for filterless and coilless FM IF detector used in the cordless telephone. It includes the external 2nd IF ceramic filter and the external discriminator in itself and that realized to be able to reduce the external parts extremely. 16-SOP-225
FEATURES
· · · Operating voltage range: 2.0 to 6.0V Typical supply current: 6.3mA at 3V Filterless & coilless FM IF detector -- Excellent demodulation characteristics -- Intermediate frequency is 76kHz -- Include the IF band pass filter (active RC filter) -- Include the phase shifter (for discriminator) -- Dual feedback IF detect system (for the image rejection of mixer) -- The only function to be tuned is the resonant frequency of the oscillator -- Minimum number of external parts required
ORDERING INFORMATION
Device S1A0429A01-S0BA Package 16-SOP-225 Operating Temperature - 10°C to +70°C
1
S1A0429A
FILTERLESS WIDEBAND FM IF DETECTOR
BLOCK DIAGRAM
AFLT1 16
AFLT2 15
AFO 14
RFin13
RFin+ 12
IFLT1 11 BPF
IFLT2 10
RSSI
9
Audio Filter
Mixer
Path control
Limiter vco
Demodulator
1
DEMO
2
TMC
3
GND
4
Vcc
5
OSC
6
DECPL
7
IFLT4
8
IFLT3
PIN CONFIGURATION
DEMo TMC GND Vcc OSC DECPL IFLT4 IFLT3
1 2 3 4 5 6 7 8
16 15 14
AFLT1 AFLT2 AFo RFinRFin+ IFLT1 IFLT2 RSSI
S1A0429A
13 12 11 10 9
2
FILTERLESS WIDEBAND FM IF DETECTOR
S1A0429A
PIN DESCRIPTION
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Symbol DEMO TMC GND Vcc OSC DECPL IFLT4 IFLT3 RSSI IFLT2 IFLT1 RFin+ RFinAFO AFLT2 AFLT1 Description Demodulator output terminal, low pass filtering with the external capacitor This terminal stabilizes the control of audio signal path with the external capacitor Ground Supply voltage Local oscillator terminal The external local signal injection is possible as this terminal connects resister to Vcc Internal IF AMP (Limiter) de-coupling terminal for DC bias IF band pass filter terminal for high cut-off frequency IF band pass filter terminal for low cut-off frequency Received signal strength indicator If band pass filter terminal for high cut-off frequency If band pass filter terminal for low cut-off frequency Balanced input terminal of mixer Balanced input terminal of mixer Recovered audio output terminal Audio signal band pass filter terminal for high cut-off frequency Audio signal band pass filter terminal for low cut-off frequency
ABSOLUTE MAXIMUM RATINGS
Characteristics Maximum supply voltage Operating temperature Storage temperature Symbol Vcc TOPR TSTG Value 7 -10 to +70 -55 to +150 Unit V °C °C
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S1A0429A
FILTERLESS WIDEBAND FM IF DETECTOR
ELECTRICAL CHARACTERISTICS
(Vcc = 3V, fc = 98MHz, fDEV = ± 22.5kHz, fMOD = 1kHz, Ta = 25°C, VRFin = 150µVrms, unless otherwise specified) Characteristics Current consumption Input for -3dB limiting S/N ratio Detector output distortion Recovered audio output AM rejection ratio Symbol Icc VLIM S/N THDDET VO(RA) AMRR Test conditions - AFo = -3dB 0dB Ref = 150µVrms RFin - - - AM modulation = 30% Min. - - 45 - - 40 Typ. 6.3 5.0 60 0.7 90 50 Max. 8.0 13 - - - - Unit mA µVrms dB % mVrms dB
TEST CIRCUIT
RFin (98MHz) AF OUTPUT C16 100n GND 16 C15 3.3n 15 14 C13 220p 13 12 C12 220p 11 C10 4.7n
RSSI
C9 100n 10
R9 8.2K
9
S1A0429A
1
C1 10n
2
C2 100n
3
4
Cv 2-6p
5
6
C6 100n
7
8
C8 820p Vcc
R2 10k
GND
C5 56p
L5 2.7µF
C7 1.5n
4
FILTERLESS WIDEBAND FM IF DETECTOR
S1A0429A
APPLICATION CIRCUIT
RFin (10.7MHz) AF OUTPUT 4.7n 560p 0.1u GND 16 3.3n 15 330 14 220p 13 12 11 10
RSSI
0.1µ
100K
9
S1A0429A
1
2
3
4
5
6
7
8
560p
10k
6.8n
10n
GND
56p Vcc
100n
1.5n Vcc
shin Woo's coil 7BS-C4037 TEL: 832-0343-74-5040
5
S1A0429A
FILTERLESS WIDEBAND FM IF DETECTOR
EXTERNAL PARTS DESCRIPTION (See Figure 3) C1 C2 Eliminates IF harmonics at the output of the demodulator. Stabilizes on/off switching of audio signal path. The function of path control block can controlled by audio on/off signal path from demodulator to audio filter If R2 is connected to PIN2, audio signal path is always on state. Determines the frequency of the local oscillator. Oscillated level can be suppressed with shunt resistor. The values of C5, L5 and Cv depend on the required tunning range. Decouples the DC feedback of limiter. Decouples the DC feedback of limiter.
C5, L5, Cv
C6
C7, C8, C10 Determine the center frequency and bandwidth of active IF bandpass filter. This BPF determines selectivity characteristics and demodulated output distortion characteristics. C7, C10 determines the high cut-off frequency (fHP). C8 determines the low cut-off frequency (fLP).
1 f LP 1 = -------------------------------------2 R i 10 C i 10 C 10 1 f HP 2 = ----------------------2 R i 7 C 7 1 f LP 2 = ----------------------2 R i 8 C 8
Internal parts Ri10 = 2.2k, Ci10 = 148pF Ri7 = 4.7k Ri8 = 4.7k
C9 R9 C15, C16
Eliminates IF harmonics at the RSSI output. Determines RSSI slope which is inversely proportional to RFin(dBm), adjust the slope and level of RSSI output. Determines the cut-off frequency of audio band pass filter C15 determines the high cut-off frequency (fHP). C16 determines the low cut-off frequency (fLP).
1 f HP = ---------------------------2 R i 15 C15 1 f LP = ---------------------------2 R i 16 C 16
Internal parts Ri15 = 12.3k Ri16 = 14k
6