PGA2310 as quality VCA

[dmitttri]

Hello folks!!

Did anybody tried to implement envelope generator application (VCA application) with this BB chip?

More precise, digitaly controlled analog amplitude.

I have problems due to audibile clicking and poping, despite all precautions from datasheet in PCB realisation (separate DGND and AGND).

I buffered PGA2310 with OPA2604, both input and output to ensure low DC and inpedance on PGA input. Zero crossing is enabled, for sure, and PGA is used only as attenuator.

Perhaps the problem is application nature, where jumps in attenuation level greater than +-1 dB are common, specialy on fast attack and release sections. Envelople resolution is 10 ms, and i did some testings with 5 khz sine (to ensure that zero crossing can work OK (pga2310.pdf)), around 3V rms.

I applied triangle envelope, from my atmel MCU, with 1 dB step up and down. Pops and clicks are audibile, and situation is getting worse by increasing attenuation steps (4dB, 8dB).

Does anybody have some extended expiriences with PGA2310, except standard application for 5.1 or stereo volume control?

PS I am thinking of SSM2614 (quad analogue VCA), but only as last possible solution...

THANKS IN ADVANCE!