MC145483 Datasheet | Motorola Semiconductor

.. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Order this document by MC145483/D Product Preview 3 V 13-Bit Linear PCM Codec-Filter The MC145483 is a 13- bit linear PCM Codec- Filter with 2s plement data format, and is offered in 20- pin SOG and SSOP packages. This device performs the voice digitization and reconstruction as well as the band limiting and smoothing required for the voice coding in digital munication systems. This device is designed to operate in both synchronous and asynchronous applications and contains an on- chip precision reference voltage. This device has an input operational amplifier whose output is the input to the encoder section. The encoder section immediately low- pass filters the analog signal with an active R- C filter to eliminate very high frequency noise from being modulated down to the passband by the switched capacitor filter. From the active R- C filter, the analog signal is converted to a differential signal. From this point, all analog signal processing is done differentially. This allows processing of an analog signal that is twice the amplitude allowed by a single- ended design, which reduces the significance of noise to both the inverted and non- inverted signal paths. Another advantage of this differential design is that noise injected via the power supplies is a mon- mode signal that is cancelled when the inverted and non- inverted signals are rebined. This dramatically improves the power supply rejection ratio. After the differential converter, a differential switched capacitor filter band- passes the analog signal from 200 Hz to 3400 Hz before the signal is digitized by the differential 13- bit linear A/D converter. The digital output is 2s plement format. The decoder digital input accepts 2s plement data and reconstructs it using a differential 13- bit linear D/A converter. The output of the D/A is low- pass filtered at 3400 Hz and sin X/X pensated by a differential switched capacitor filter. The signal is then filtered by an...