Dual-Mode design of Fully-differential Circuits using Fully-Balanced Operational Amplifiers

E SPINELLI; M. MAYOSKY; C. CHRISTIANSEN

IEE PROCEEDINGS. CIRCUITS, DEVICES AND SYSTEMS

IEE

Año: 2008 vol. 2 p. 243 - 248

1350-2409

Fully-Differential (F-D) analog circuits are usually designed focusing only on their differential mode behavior, without considering common mode dynamics. This paper presents a technique for the design of both differential mode and common mode circuit responses, using Fully Balanced Operational Amplifiers (FBOA) as analog building blocks. FBOAs work with common mode and differential mode voltages as a whole, having an ideally infinite gain for both modes. This allows independent design of common mode and differential mode dynamics. Inverting and non-inverting Fully-Differential topologies can be implemented in a simple way, similar to that of their Single-Ended (S-E) counterparts. Some typical application circuits are analyzed and discussed and, as a design example, a “double-mode oscillator” (a circuit that has independent common mode and differential mode oscillations) was built and experimentally evaluated.