Design of quadrature delta sigma modulator for global navigation satellite system receivers

The global navigation satellite system is widely used in the guidance of military equipment, police. the quality of their receivers is very important due to low power level of these types of signals. In this paper, a continuous time wideband three-bit analog-to-digital quadrature delta sigma converter for a two-channel Global Navigation Satellite System (GNSS) receiver in different modes is designed. The proposed modulator is designed in FF structure. In the FF structure, there are two power hungry adders before the quantizer, which have been eliminated in the proposed design method. This action has reduced the number of op-amps, and as a result, has reduced the total power consumption of the modulator. The proposed modulator has a lower order of magnitude compared to similar modulators with the same bandwidth, and as a result has a lower number of op-amps, which reduces power consumption and also has more relative stability. This three-bit modulator is able to convert two separate channels with different bandwidths and in different modes up to 33 MHz bandwidth with a signal to noise ratio (SNR) of 64.8 dB at the same time as digital.