I’ll need at least two envelopes: one for the filter and one for the volume. I’m mixing it up a little by picking a Doepfer A-140 ADSR and a TipTop Audio Z4000 Envelope Generator. The A-140 is a basic ADSR envelope. It has two outputs for the envelope signal (so it can control two other units simultaneously) and one which outputs the inverted envelope signal. It also has a re-trigger input which restarts the envelope generation every time it goes high and the gate signal is also high.
The Z4000 is also an ADSR envelope but with some extra bells and whistles. In addition to the knobs controlling the attack, decay and release lengths and the sustain level (like on the A-140) the Z4000 also has voltage control inputs for those parameters, which is a rather useful feature. It can invert the envelope but also add or subtract a level offset from it. This module also has a trig-button that manually triggers the envelope, and a switch to select a logarithmic or exponential attack slope.
1 TipTop Audio Z4000 Envelope Generator
1 Doepfer A-140 ADSR