A compensation method of the excess loop delay in continuous-time complex sigma-delta modulators

Effect of Mismatched Loop Delay in Continuous-Time Complex Sigma-Delta Modulators

“…The DT-loop filter has also and as parameters but as input. It can also be seen that, when and is the same as zero and is identical to the results in [3] and [4], where they described the DT-equivalent with common loop delay.…”

“…Because the compensation method of common loop delay has already been proposed for CT complex modulators [4], it can be used for compensation here. Therefore, when D-latches and the compensation scheme for the common loop delay are used for the modulator design, the degradation in SNR by mismatched loop delay can be improved.…”

“…Compensation methods of excess loop delay in CT low-pass and real band-pass modulators have previously been proposed [1], [2]. However, compensation in CT complex bandpass modulators has only been considered for identical loop delay in the I/Q paths [3], [4].…”

A New Approach to Complex Bandpass Sigma Delta Modulator Design for GPS/Galileo Receiver

“…Figure 5 shows the proposed two order complex filter schematic for the GPS/ Galileo modulators, which is useful to low power, low resolution and low data rate. As can be seen in Figure 5, the OTA-C lossy integrators are used for degradation in excess loop delay and mismatch loop delay sensitivity [9]. Furthermore the lossy integrators are used for securing of stability.…”

“…That is determined the transconductors and capacitances according to Table 1. 3.3. Quantizer Figure 6 shows c The quantizer consists of a one bit comparator, followed by a D-latch [9]. Two differential amplifiers with diode loads by transistors M1-M10 are used as pre-amplifier and front-end of comparator.…”