Low cost high linearity solid state digital double boxcar

In this article, we describe a digital solid state double boxcar of infinite holding time and very high linearity. It uses a Hewlett-Packard (HP2212 A-M3) voltage-to-frequency converter (VFC) whose output is accumulated on a running counter, thereby providing signal averaging with an infinite holding time. The combination of FET signal gates with zero offset and the highly linear VFC results in a linearity of better than ± 0 . 0 1% over an input range of ± 1 . 0 V, which is a considerable improvement over that available with other digital boxcars. Integrated circuit pulse generators of high stability provide gating times from a fraction of a microsecond to many seconds. A unique monitoring system allows ease of adjustment with a simultaneous "master" display of all gating and signal functions. Other features of this boxcar are extreme compactness, low cost, and very high stability.