Nokia 5110 COBBA (Baseband, Audio)

Thanks to Martijn Boer for providing the board with this chip on it.

 

This chip was really hard to identify, and I had to dig up some Nokia 5110 service manuals and technical documents to even identify it and get a rough idea of what it does. Upon searching the writing on the chip package, I found nothing relevant, so I went ahead and cracked it open in hopes that an on-die marking could help me out. At the center of the chip there is some inscriptions which gave me some clues. First off, the TWL91310 or MSW/ABB strings did not bring up anything. The COBBAGJ string is what led me to discover the Nokia 5110 service manuals which told me what this chip is. Also on the bottom left there is the Texas Instruments logo and a timestamp for 1999. This leads me to believe it was probably a custom design requested by Nokia since you can usually find Texas instruments datasheets quite easily.

 

Here's a section from the technical documentation explaining what this chip does:

 

"The COBBA–GJ provides an interface between the baseband and the RF–circuitry. COBBA–GJ performs analogue to digital conversion of the receive signal. For transmit path COBBA_GJ performs digital to analogue conversion of the transmit amplifier power control ramp and the in–phase and quadrature signals. A slow speed digital to analogue converter will provide automatic frequency control (AFC). The COBBA asic is at any time connected to MAD asic with two interfaces, one for transferring tx and rx data between MAD and COBBA and one for transferring codec rx/tx samples."

 

(MAD is the main processor of the phone, largest chip on the board)

 

So it appears to be responsible for some cellular signal processing. In other places in the technical documentation it also talks about how this chip handles some audio processing and codecs as well.

 

Also, there is an American flag in the top right of the image, close up here: flic.kr/p/2memuEn

 

Camera: SONY A6000

Number of Images: 63

Panorama Y Axis: 9 Images

Panorama X Axis: 7 Images

ISO: 100

Shutter Speed: 1/3"

Light Source: Internal Lamp

DIC: Yes

Overlap: 50%

Microscope Objective: 10X

Microscope Eyepiece: DSLR Mount

Grid Used: 4x4 (Panning Movement Aid)

Capture Motion: ZigZag

Stitching Software: Autopano Giga

Other Software: Gimp for white-balancing and sharpening.

Image Type: JPG, 96% quality

Done