This paper explores voltage-controlled amplifier (VCA) designs based on operational transconductance amplifiers (OTAs) on a floating-gate--based Field-Programmable Analog Array (FPAA). Although preconfigured OTAs are available on the target FPAA, their gain must be fixed during the programming stage. Hence, the OTA that forms the variable-gain element the VCA must be constructed from the individual transistors that are also available on the FPAA. The current output of this more-flexible OTA is converted to a voltage via one of the built-in fixed-gain OTAs. The authors show how the use of a special floating-gate OTA with voltage attenuation at its inputs arising from capacitor dividers (analogous to resistor dividers used in traditional printed circuit board--level VCA designs) helps prevent a diverging nonlinearity from ruining the current-to-voltage conversion process. This exercise highlights the counterintuitive challenges facing engineers moving from board-level audio design with off-the-shelf chips and discrete bipolar junction transistors to very large--scale integration--level design with complementary metal oxide semiconductor technology.
Click to purchase paper as a non-member or you can login as an AES member to see more options.
No AES members have commented on this report yet.
To be notified of new comments on this report you can
subscribe to this RSS feed.
Forum users should login to see additional options.
If you are not yet an AES member and have something important to say about this report then we urge you to join the AES today and make your voice heard. You can join online today by clicking here.
