The block is third order cascade (2-1) delta-sigma ADC with 5-level quantizer in both stages. The block consists of:
Two delta-sigma modulators second and first order, coupled in series and combined by noise cancellation logic
Block of bias currents, tunable (3-bit control)
Block of reference voltages, tunable (5-bit control)
Clock frequency divider (4-bit control)
DWA-correction of capacitors’ mismatch
Output signal is represented in thermometer code at the output of each stage. There is a possibility to disable the second stage of modulator to save the power with decreased accuracy. Next to options included: DWA correction algorithm; tuning of reference voltages buffers; tuning of bias current for operational amplifiers with 3-bit control; the clock frequency divider with integer ratio 1- 15.
Input signal common mode voltage is 1.65 V; recommended values of reference voltages: 0.9 ± 0.4 V; recommended differential input signal amplitude - 0.64 V; allowable duty cycle: 50 ± 5%.
The block is designed on iHP SiGe BiCMOS 0.13 um technology.