As is known in the art, radar systems often utilize a radio frequency (RF) signal modulated by an analog waveform. Although it is desirable to provide relatively accurate analog waveforms, it is also sometimes desirable to provide low cost systems. Thus, in such relatively low cost systems, single bit conversion is typically used to generate a desired analog waveform.
As is also known, conventional single bit converters typically use Pulse Width Modulation (PWM) or Delta Sigma Modulation (DSM). PWM converters generate pulses at a fixed frequency. The pulses have a pulse width which is proportional to the desired output voltage. The switching noise generated by this converter contains low frequencies, which are difficult to filter. Thus, while PWM converters are relatively simple and inexpensive, they also do not provide a suitable level of accuracy for many applications.
DSM converters are more sophisticated than PWM converters. DSM converters typically utilize a digital feedback arrangement to shift the switching noise higher in frequency, where it can more easily be filtered. Thus, while DSM converter techniques typically provide a desired level of accuracy, they are relatively sophisticated and thus relatively expensive. They also typically require a relatively high clock rate.
USPTO Backgrounds
USPTO Backgrounds