Digital to analog converter with reduced ringing
AssigneeBroadcom Corporation
InventorsKlaas Bult, Chi-Hung Lin
Life of this patent
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Abstract
Binary indications are converted to an analog representation with significant reduction in ringing at the transitions between successive binary indications and in the period during each binary indication. The binary indications are disposed in a row-and-column matrix to provide a thermometer code. Each stage of the converter includes a decoder and latch arranged so the decoder inputs settle before the latch is set by the clock pulses. The stages are implemented in complementary CMOS. Complementary transistors are biased so one transistor of the pair is driven to the rail while the other transistor of the pair floats. A dummy CMOS transistor is used to balance the number of transistors in the decoder paths.
Claims6
A digital to analog converter (DAC) comprising:
- a first bias source having a potential of one polarity;
- a second bias source having a potential of the other polarity;
- a bistable latch biased by the sources, the latch having first and second complementary terminals;
- first and second complementary data decoders;
- means for alternately connecting one of the data decoders to the first bias source while the other data decoder floats;
- and
- first and second transfer switches coupling the first and second decoders to the first and second terminals, respectively, responsive to timing pulses.
A digital to analog converter (DAC) for converting a multi-bit binary signal to an analog signal representative of the combined values of the binary signal, the DAC comprising:
- a first bias source having a potential of one polarity;
- a second bias source having a potential of the other polarity;
- a plurality of cells each having:
- a bistable latch biased by the sources, the latch having first and second complementary terminals;
- first and second complementary data decoders;
- means for connecting the first data decoder to the first bias source while the second data decoder floats;
- means for connecting the second data decoder the first bias source while the first data decoder floats;
- and
- first and second transfer switches coupling the first and second decoders to the first and second terminals, respectively, responsive to timing pulses.
Dependencies are inferred from the claim text.