This week, I completed the analog path schematic design which was the goal I stated last week. As a group, we decided to change the synthesizer architecture to be duophonic rather than polyphonic, so there are two VCFs and VCAs with independent control signals. I added ample power supply decoupling and RF chokes to separate the analog and digital supplies. There is a high speed I2S DAC for audio which has two channels (right, left) followed by two VCFs with both adjustable cutoff frequency and resonance, then two VCAs. The output of the VCAs is buffered with opamps and an 8-channel I2C DAC is used to generate the control signals which drive VCFs and VCAs.
Completing this puts me perfectly on schedule, which is great. For next week, I want to finish the power supply section (only the 3.3v rails are done, need to add low noise 5V regulators too) and get a solid plan for the front panel interface. This includes ordering the correct number of potentiometers, rotary encoders, and knobs as well as starting the schematic design.