The IIS Chip Gallery
Cohere (2004)
by
| Application | Audio |
| Technology | 250 |
| Manufacturer | UMC |
| Type | Semester Thesis |
| Package | LCC84 |
| Dimensions | 2500μm x 2500μm |
| Gates | 70 kGE |
| Voltage | 2.5 V |
| Power | 165 mW, 60MHz, 2.5V |
| Clock | 100 MHz |
Different applications, such as radio dramas, games for PCs and others, take advantage from knowing in real time the direction, from which a recorded voice or sound is coming from. In the first phase, the sound is recorded by means of both a near-distance microphone and an artificial head (see inlet in the picture). In the second phase, the so called rendering, the near-microphone recording is combined with the spatial information coming from the artificial head, to reproduce a high quality sound, together with the impression of the movement in a virtual environment.
The 3D audio correlator ASIC called CohereChip (main image in the picture) is used to extract the spatial information out of the stereo recording of the artificial head in real time. To achieve such a result, it performs 72 correlations with as many Head Related Transfer Functions (HRTF). These are nothing else than predetermined impulse responses with an angle displacement of 5º in the given environment. The 3D audio correlator chip outputs the direction of origin of the sound, by calculating the maximum among the different correlation values. Some relevant features of the chip are: