Abstract: A variable gain amplifier including common emitter input transistor, a plurality of common base switching transistor to form a cascode amplifier with said input transistor and a resistive network including a plurality of series resistors is disclosed. A plurality of predetermined gains are obtained by programming the resistors. The resistive network may be shared by two or more variable gain amplifiers to provide a selection amplifier.

Abstract: A calibration apparatus for analog-to-digital converter or transient recorder including both analog and digital sections is disclosed. A built-in calibrator automatically calibrates the gain and DC level of the entire system to substantially the same accuracy as that of the digital section, thereby avoiding relatively large errors of the analog section. The amplitude or gain calibration is always performed over the full range of the digitizer used in the digital section.

Abstract: A high speed analog-to-digital conversion method and apparatus including a plurality of parallel analog-to-digital converters is disclosed. A clock signal is applied to each of the analog-to-digital converters at different phase relation to increase the equivalent sampling frequency by multiplexing the outputs into a serial form. A reference signal such as a linear ramp or sawtooth signal is used to maintain the correct phase relation, thereby eliminating any errors due to differences in electrical characteristics among the analog-to-digital converters. Such correction may be performed automatically by using a CPU before digitizing an analog input signal or at any desired time.