XR-215A Datasheet, PDF (20/32 Pages) Exar Corporation – Monolithic Phase Locked Loop

XR-215A
Multi-Channel Demodulation
The AC digital programming capability of the XR-215A allows a single circuit be time-shared or multiplexed between two
information channels, and thereby selectively demodulate two separate carrier frequencies. Figure 19 shows a
practical circuit configuration for time-multiplexing the XR-215A between two FM channels, at 1MHz and 1.1MHz
respectively. The channel-select logic signal is applied to pin 10, as shown in Figure 19 with both input channels
simultaneously present at the PLL input (pin 4). Figure 20 shows the demodulated output as a function of the
channel-select pulse where the two inputs have sinusoidal and triangular FM modulation respectively.
186400000_{ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ(VffomTIeÎÎÎÎÎÎÎÎÎÎÎNo=sd1=t=0C2ÎÎÎÎÎÎÎÎÎÎÎM10ircHKmuHzÎÎÎÎÎÎÎÎÎÎÎiVtzormf FÎÎÎÎÎÎÎÎÎÎÎsigurÎÎÎÎÎÎÎÎÎÎÎe 5)ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ}
0.01%
0.1%
1.0%
10%
100%
Frequency Deviation Df/f_o
Figure 17. Output Signal/Noise Ratio as a Function of FM Deviation
1%
0.5%
0
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ_{VfV(fomTIOeNo=U}ÎÎÎÎÎÎÎÎÎ_{sd1=Tt0=C2=M10i}ÎÎÎÎÎÎÎÎÎ_{rCHKcmuHoziVnzt}ÎÎÎÎÎÎÎÎÎ_sortmfaFnsÎÎÎÎÎÎÎÎÎ_tig@ure2ÎÎÎÎÎÎÎÎÎ_5V)PÎÎÎÎÎÎÎÎÎ_P ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
0.01%
0.1%
1.0%
10%
100%
Frequency Deviation Df/f_o
Figure 18. Output Distortion as a Function of FM Deviation
Rev. 1.01
20