Design of very low‐distortion, four‐quadrant analog multiplier‐type CMOS‐OTA considering variation of mobility according to the gate voltage

Abstract

AbstractThis paper discusses the four‐quadrant multiplier‐type operational transconductance amplifier (FQAMTOTA). the basic principle of its operation is described. the circuit uses four MOSFETs (MRA) operating in the resistor region as well as the identical voltage level‐shift circuit (IVLS). Although it has a simple structure, its feature is that it has a wide linear input range and the transconductance can be controlled for both signs. For the FQAMT‐OTA to operate at a high‐frequency signal range, MOSFET with a short channel must be used as MRA.In most of the past designs of CMOS circuits, the effective carrier mobility μ is assumed as constant. In practice, however, μ has the property that it depends on the gate‐source voltage. This effect cannot be ignored when the circuit is designed using MOSFET with a short channel because it can cause a large second‐order harmonic distortion in the output of FQAMT‐OTA. Another point is that the power consumption increases when MOSFET with a short channel is used. the idea in this paper is that those problems can be remedied only by using the bootstrap circuit as MRA. A construction of the improved FQAMT‐OTA is shown together with the result of simulation using PSpice.