Device for extending the resolution of a n-bit resistive digital to analog converter to a (N+P)-bit digital to analog.

摘要

Device implemented in a N-bit digital to analog converter DAC to extend its resolution to N+P bits. The N-bit DAC comprises a resistive string 2 made of 2 resistive elements R1 to R16. MSB switches in block 10 and LSB switches in block 12, when closed in response to combinations of the N-bits provide the voltage at one of taps N1 to N16 to node M1. The device comprises a string 18 made of 2 elements connected between nodes M1 and M7, additional LSB switch block 14 and additional MSB switches SW4-2, SW8-2, SW12-2 and SW16-2 which are closed in response to combinations of the N-bits to connect the string 18 across the taps of a selected resistor R1 to R16. The voltage generated at one of the taps M1 to M7 of string 18 is provided to the (N+P)-bit digital to analog converter output 20 by means of one of the switches in block 16. The main advantages of this device are that the monotonicity of the conversion is not impaired by the extension to (N+P) bits, and that it is not space consuming when integrated in a chip. Furthermore, various conversion capabilities may be provided by controlling the switch SW21 and the switches in block 16.