US 11,811,420 B2
Digital-to-analog converter with cascaded least significant bit (LSB) interpolator circuit
Abdullah Yilmaz, Tucson, AZ (US)
Assigned to Texas Instruments Incorporated, Dallas, TX (US)
Filed by Texas Instruments Incorporated, Dallas, TX (US)
Filed on Jan. 21, 2022, as Appl. No. 17/581,516.
Prior Publication US 2023/0238980 A1, Jul. 27, 2023
Int. Cl. H03M 1/66 (2006.01)
CPC H03M 1/661 (2013.01) 22 Claims
OG exemplary drawing
 
1. A digital-to-analog converter (DAC) for converting a digital input word to an analog output signal, the DAC comprising:
a string DAC comprising:
a plurality of series-connected resistors; and
a most significant bit (MSB) switching circuit including pairs of switches, each pair of switches having an upper switch and a lower switch, each upper switch is connected to an upper terminal of one of the plurality of series-connected resistors and each lower switch is connected to a lower terminal of one of the plurality of series-connected resistors, the MSB switching circuit operable to provide a first voltage and a second voltage in response to an MSB control signal;
a first least significant bit (LSB) interpolator coupled to the string DAC and having an output, a plurality of non-inverting inputs and a plurality of inverting inputs coupled to the output, one of the non-inverting inputs coupled to receive the first voltage and the other non-inverting inputs coupled to receive the first or the second voltage, the first LSB interpolator operable to provide a first interpolated voltage at the output in response to a first LSB control signal; and
a second LSB interpolator coupled to the string DAC and the first LSB interpolator, the second LSB interpolator having an output, a plurality of non-inverting inputs and a plurality of inverting inputs coupled to the output, one of the non-inverting inputs coupled to receive the first interpolated voltage and the other non-inverting inputs coupled to receive the first voltage or the second voltage, the second LSB interpolator operable to provide an output voltage at the output in response to a second LSB control signal.