Apparatus and method for analogue to digital conversion

Claim 1

An interpolating analogue to digital converter, comprising: a first analogue signal combiner having first and second inputs, and an output, and being arranged to receive at said first input a continuously variable analogue input signal having a predetermined bandwidth and being arranged to receive at said second input a quantization error signal in analogue form and to provide at said output a combined version of the signals at said first and second inputs; a one step digital quantizer means directly coupled to said output of the first signal combiner for producing a binary valued quantized signal, and clock means connected to the quantizer means having a clock rate substantially greater than the predetermined bandwidth of the input signal; a second signal combiner having a first input, a second input and output, the first input being coupled to receive said quantized signal and a second input being directly coupled to said output of the first signal combiner to receive a feed forward signal therefrom whereby to provide at said output of the second signal combiner said quantization error signal; and, feedback means for directly coupling the quantization error signal to the second input of the first combiner; the arrangement being such that said quantizer means provides a serial output of pulses representing a digitized value of the input signal.