Slide 12 of 16
Notes:
In this application, a network telephony server, the requirement is to handle 30 vocoder channels (like G.728, G.729, G.723, etc.). The previous design used 16 C51 devices, each channel requires one 40 MIPS DSP. The desire is to implement 30 channels (one E1 line) in the system. One C51 per channel and 1 C51 acts as a controller for the board (16 total). The DSP cost of the existing system is around $660 (30 C51s * $22). This results in a per channel cost of $22. The power consumption per channel is around 380 mW (5V x 1.9 mA/MIPS x 40 MIPS). Each C51 is in a 24mm x 24mm package. This translates to 576 mm2 per channel. While this does not consider the routing of the 132 pins, the number is useful for rough comparisons to new alternatives. Overall, the “benchmarks” to beat in the new system are: $22 per channel, 380 mW / channel, and 576 mm2 per channel.
The new design needs to be smaller, cheaper, and lower power dissipation.
