dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 36

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

Introduction
Processing in this circuit begins with band limiting the input signal with an anti-alias filter, which
eliminates out-of-band signals that can be aliased back into the pass band due to the sampling process. The
signal is then sampled, digitized with an A/D converter, and sent to the DSC. The DSC output is processed
by a D/A converter and is low-pass filtered to remove the effects of digitizing.
The particular filter implemented by the DSC is strictly a matter of software. The DSC can implement any
filter that can be implemented using analog techniques. Moreover, adaptive filters, which are extremely
difficult to implement using analog techniques, can easily be created using DSC.
In summary, the advantages of using the DSC include the following:
1-6
x(t)
•
•
•
Fewer components
Stable, deterministic performance
No filter adjustments
Anti-Aliasing
Low-Pass
Analog In
Filter
Analog-to-Digital
Analog
Sampler And
Digital
Filter
Filter
Filter
Ideal
Converter
A/D
Figure 1-4. Digital Signal Processing
DSP56800E Core Reference Manual
A
A
A
x(n)
k
N
∑
DSC Operation
=
Finite Impulse
–
1
0
Response
FIR Filter
Frequency
Frequency
Frequency
c k ( )
×
(
n k
–
)
f
f
f
c
c
c
Digital-to-Analog
y(n)
Converter
D/A
Freescale Semiconductor
f
f
f
Analog Out
Reconstruction
Low-Pass
AA0004
y(t)