Plural stage switched capacitor integrating digital-to-analog converter

摘要

The digital-to-analog converter for converting a digital signal having a word length n into an analog signal comprises at least two switched capacitor integrators (1, 2) arranged in series and a control unit (18) for applying control signals to the integrators for performing an integration step in an integrator under the influence of a control signal applied to this integrator. Each integrator (1; 2) comprises a capacitor network (11; 12) comprising at least two capacitors (27.1, 27.2, ......; 28.1, 28.2, ....) coupled between the input (13; 4) of the integrator and the inverting input (-) of an amplifier stage (5; 6) associated with the integrator. A capacitor (9; 10) is coupled between the inverting input (-) and the output (7; 8) of this amplifier stage (5; 6). The control unit (18) is adapted to apply, in this order, a first control signal to the first integrator (1), a second control signal to the second integrator (2), a third control signal to the first integrator and a fourth control signal to the second integrator. The first integrator (1) couples a total capacitance of M1.Cref1 and M3.Cref1 during a given time interval to the inverting input of the amplifier stage (5) under the influence of the first and the third control signal, respectively. The second integrator (2) couples a total capacitance of M2.Cref2 and M4.Cref2 during a given time interval to the inverting input of the amplifier stage (6) under the influence of the second and the fourth control signal, respectively. For converting an arbitrary digital signal it holds that M2 + M4 is equal to a constant (k) which is preferably equal to 2 in which p