TP3057N/NOPB

The TP3057N/NOPB is an enhanced serial interface CODEC/Filter Combo consists of µ-law and A-law monolithic PCM CODEC/filters utilizing the A/D and D/A conversion architecture and a serial PCM interface. It is fabricated using National's advanced double-poly CMOS process (microCMOS). The encode portion of each device consists of an input gain adjust amplifier, an active RC pre-filter which eliminates very high frequency noise prior to entering a switched-capacitor band-pass filter that rejects signals below 200 and above 3400Hz. Also included are auto-zero circuitry and a companding coder which samples the filtered signal and encodes it in the companded µ-law or A-law PCM format. The decode portion of each device consists of an expanding decoder, which reconstructs the analog signal from the commanded µ-law or A-law code, a low-pass filter which corrects for the sin x/x response of the decoder output and rejects signals above 3400Hz.