Circuit for multiplying an analog value by a digital value
AssigneeYozan Inc.
InventorsGuoliang Shou, Weikang Yang, Sunao Takatori, Makoto Yamamoto
Life of this patent
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Abstract
A multiplication circuit directly multiplying an analog and a digital data without converting analog/digital or digital/analog converting. An analog input voltage is controlled by a switching signal of a digital voltage so as to generate an analog output or cut-off the outputs. Digital input signals b.sub.0 to b.sub.7 of a plural number of bits is integrated giving weights by means of a capacitive coupling, and a sign bit is added by a capacitive coupling CP with a double weight of the most significant bit ("MSB") of the digital input.
Claims11
A multiplication circuit comprising:
- i) a capacitive coupling element which comprises a plurality of first capacitors connected in parallel with capacitive values corresponding to weights of each bit of a digital data;
- ii) a first switching circuit connected with the first capacitors of said capacitive coupling element, said switching circuit being opened and closed by a digital voltage corresponding to each bit of said digital data;
- iii) a first inverter connected with an output of said capacitive coupling element;
- iv) a second capacitor connected with an output of said first inverter;
- v) a second inverter connected with said first inverter through said second capacitor;
- vi) a second switching circuit connected with an output of the second inverter and said output of said first inverter for outputting alternatively one of said outputs;
- and
- vii) an analog input voltage connected with said first switching circuit.
A digital/analog multiplier, comprising:
- a bridge of switching elements, each receiving an analog signal to be multiplied, and each receiving a respective bit of a digital signal to be multiplied, said bridge of switching elements selectively switching on or off voltages dependent on bit of said digital signal and producing an output signal indicative of a multiplication product between said analog signal and said digital signal;
- an inverting element, receiving the output of said bridge, and inverting a sense of an analog voltage represented thereby;
- and
- a switch, receiving a sign bit of the digital signal, and receiving an inverted an a non-inverted result of multiplication, said sign bit selecting which of said inverted or non-inverted output is produced.
Dependencies are inferred from the claim text.