PSB2163T-V31TR Infineon Technologies, PSB2163T-V31TR Datasheet - Page 259

• Manufacturer Part Number: PSB2163T-V31TR
• Description: IC AUDIO RINGING CODEC 28-PDSO
• Manufacturer: Infineon Technologies
• Series: ARCOFI®r

Specifications of PSB2163T-V31TR

• Function: CODEC Filter
• Interface: IOM-2, PCI, Serial
• Number Of Circuits: 1
• Voltage - Supply: 5V
• Current - Supply: 900µA
• Power (watts): 1mW
• Operating Temperature: -25°C ~ 80°C
• Mounting Type: Surface Mount
• Package / Case: DSO-28
• Includes: Activation and Deactivation, B-Channel and D-Channel HDLC Controllers, D-Channel Priority Handler, Monitor Channel Handler
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Other names: PSB2163T-V31INTR; PSB2163T-V31TR

3
3.1
Two high performance frequency correction filters FX and FR are implemented in the
ARCOFI-SP, allowing an optimum adaption to different types of transducers or
compensating the frequency response of the telephone plastics itself. Specifications of
different countries can be fulfilled by means of a simple software change.
One filter consists of two equalizers with variable gain, factor of quality, and center
frequency followed by a high-/low-pass filter. The filters can only attenuate the signal,
they behave like passive filters. The FX or FR filter is adjusted with the help of twelve
coefficients which are calculated by the ARCOS-SP PLUS software.
It is obvious, that there are different ways to configure the two equalizers and the high-/
low-pass filter to achieve one and the same frequency response. Therefore always more
than one coefficient set is capable of fulfilling the desired response.
The basic idea for calculating the coefficients is, that two frequency responses are given.
One represents the desired over-all frequency response (target function), the other one
is the frequency response, that the hardware actually offers (input function). While the
first one is usually a flat frequency response, the latter one can be measured or
estimated. ARCOS-SP PLUS then calculates the filter coefficients (filter function) in a
way, that the filter function plus the input function results in the target function. If for
example the hardware transmits high frequencies only attenuated, it exhibits a kind of
low-pass function (input function). If a flat frequency response is desired (target function)
ARCOS-SP PLUS would calculate the coefficients in a way, that the FX or FR filter
shows a high-pass behavior in order to compensate the input function.
Furthermore, it is not only possible to give a desired target function but also an upper and
lower limit for the target function can be given.
The algorithm used for generating the filter coefficients is based on a stochastic method,
similar to the law of cooling: i.e. at the beginning of the process, the parameters (here the
filter coefficients) may be within a large range. This range progressively is reduced such
that the parameters converge. Up to and including the 8th calculation step the quality of
the approximation is defined by the mean square of the difference between the target
function and the addition of the filter functions of FX or FR and the input function. Thus
the discrepancy between the two curves is calculated for each sampling frequency, then
it is squared, added and finally divided by the number of the sampling frequency points.
From the 9th calculation step the quality of the approximation is defined by the greatest
absolute difference. The algorithm shows the value of the absolute minimum and the
quality of the coefficient set which is presently considered as the best solution.
In order to calculate the discrepancy properly, each amplitude curve is normalized.
Before the algorithm starts, each amplitude curve is shifted such that it has an amplitude
Semiconductor Group
Generating the Correction Filter Coefficients
Filter Implementation and Theory of Calculation
259
SIPO 2163