A:D converter producing stream of pulses

摘要

An analogue to digital converter providing an output stream of pulses whose repetition frequency is proportional to the amplitude of the input analogue waveform. The circuit provides automatic temperature compensation and reduces low frequency noise at low input signal levels. The circuit is based on an input flip flop synchronised by a clock source. This input circuit includes a comparator triggering the flip flop when a given threshold level is exceeded. A feedback loop couples this into a second flip flop controlled from the same clock and includes a second feedback loop which with a third such loop controls two transistors fed from a constant current source, the transistors acting as a current switch.