US 6,473,359 B1 · Semiconductor integrated circuit

Abstract

A D/A converter is provided with an equal current cell matrix achieved by arraying in a matrix equal current cells each having a current switch portion, a row decoder that makes selections in the direction of the rows in the equal current cell matrix and a column decoder that makes selections in the direction of the columns in the equal current cell matrix. The D/A converter is characterized in that the equal current cells are each provided with a latch circuit for achieving synchronization of an output signal from the row decoder and an output signal from the column decoder that are input to the current switch portion. Since the current is switched by the latch circuit, glitches can be completely eliminated from the signals input to the current switch portion by taking into consideration the lengths of delays at the row decoder and the column decoder and the timing of the clock to achieve an improvement in the S/N ratio. Furthermore, since no NMOS capacitance is required, the power consumption is reduced.

Claims12

Dependent claims

A semiconductor integrated circuit, comprising:

a current cell array having current cells, each of which includes first and second PMOS transistors and a current source coupled to said first and second PMOS transistors, said first and second PMOS transistors entering an ON state in response to first and second switching signals;
a first decoder circuit that outputs a first selection signal to select a specific number of current cells;
a second decoder circuit that outputs a second selection signal to select a specific number of current cells;
a plurality of logic circuits, each receiving the first and second selection signals and outputting a third selection signal;
and
a plurality of storage circuits, each receiving said third selection signal and outputting said first and second switching signals to said first and second PMOS transistors in synchronism with a control signal.

3 more elements

Dependencies are inferred from the claim text.

Semiconductor integrated circuit

Life of this patent

Semiconductor integrated circuit

Life of this patent

Abstract

Claims12