MV5089 Datasheet, PDF (3/7 Pages) Zarlink Semiconductor Inc – DTMF GENERATOR

MV5089
OUTPUT FREQUENCY
Table 1 shows the output frequency deviation from the
standard DTMF frequencies when a 3.58MHz crystal is used
as the reference.
The row and column output waveforms are digitally
synthesised using R-2R D-to-A converters (see Fig.3),
resulting in staircase approximations to a sinewave. An opamp
mixes these tones to produce a dual-tone waveform. Single
tone distortion is typically better than 7% and all distortion
components of the mixed dual-tone should be 30dB relative to
the strongest fundamental (column tone).
Standard
DTMF
(Hz)
Row
Column
f₁ 697
f₂ 770
f₃ 852
f₄ 941
f₅ 1209
f₆ 1336
f₇ 1477
f₈ 1633
Tone Output
Frequency Using
3.5795545 MHz
Crystal
701.3
771.4
857.2
935.1
1215.9
1331.7
1471.9
1645.0
% Deviation
from Standard
+0.62
+0.19
+0.61
-0.63
+0.57
-0.32
-0.35
+0.73
Low
Group
High
Group
Table 1: Output frequency deviation
V_OUT
a)
t
V_OUT
b)
t
Figure 3: Typical sinewave output (a) Row tones (b) Column tones
DISTORTION MEASUREMENTS
THD for the single tone is defined by:
100 (
V² + V² + V² + ---- V² ) %
2f 3f 4f
nf
V _fundamental
Where V2f --- Vnf are the Fourier components of the waveform.
THD for the dual tone is defined by:
100 (
V² + V² + V² + V² + V² --- V² + V² )
2R 3R nR 2C 3C
nc IMD
V² + V²
ROW
COL
where
V_ROW is the row fundamental amplitude
V_COL is the column fundamental amplitude
V_2R—V_nR are the Fourier component amplitudes of the row frequencies
V_2C—V_nC are the Fourier component amplitudes of the column frequencies
V_IMD is the sum of all intermodulation components.
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