Design and Applications of a CMOS Analog Multiplier Cell Using the Differential Difference Amplifier

Abstract

This paper presents design techniques for a wide input range CMOS differential difference amplifier (DDA) and discusses its application as a basic block in the implementation of a simple four-quadrant multiplier cell. The cell can be configured as an amplitude modulator or a one-over circuit, which are widely used in many analog signal processing applications. The DDA can also be reconfigured as an opamp, and hence can be used to design many of the opamp-based multiplier circuits. The DDA amplitude modulator (AM) uses a transistor and a resistor as the only components external to the DDA. A DDA one-over circuit, which provides an output proportional to the inverse of the input, is also achieved with the same level of simplicity. High-frequency effects due to the DDA’s finite gain-bandwidth (GB) and MOS parasitic capacitances are investigated. Experimental results obtained from a 2 µm CMOS MOSIS chip are given.

Parts of this work have been presented at the 10th Norchlp Seminar, Helsinki, Finland, November 3–4, 1992 and included in the Seminar’s proceedings, pp. 9–14. This work was supported in part by the NSF grant MIP-8896244 and by the Semiconductor Research Corporation contracts 90-DJ-066 and 91-DJ-066, and in part by the Norwegian NTNF, SINTEF and Nordic VLSI.