Title:
D/A CONVERTING CIRCUIT
Document Type and Number:
Japanese Patent JP3388143
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To preform precise D/A conversion.
SOLUTION: Digital data D1 of a sampling frequency fs after quadruple oversampling is noise-shaped by a ΔR modulation noise shaping circuit 2 and is outputted as quinary digital data of a sampling frequency 32fs. A PWM modulating circuit 3A which has outputs of two systems (a) and (b) receives an input Y and performs PWM modulation so that Y is proportional to a value obtained by adding the output pulse widths of the two system. Each time the PWM modulating circuit 3A receives an input T, a switching circuit 10 switches to input the output (a) of the PWM modulating circuit 3A to a buffer amplifier 41 and the output (b) to a buffer amplifier 42, or inputs the output (b) to the buffer amplifier 41 and the output (a) to the buffer amplifier 42. The outputs of the buffer amplifiers 41 and 42 are added by an adding circuit 6A and passed through an analog low-pass filter 7 having a cutoff frequency below fs/2.
Inventors:
Issei Nishimura
Application Number:
JP20241397A
Publication Date:
March 17, 2003
Filing Date:
July 12, 1997
Export Citation:
Assignee:
Kenwood Corporation
International Classes:
H03M1/08; H03M1/82; H03M3/02; (IPC1-7): H03M3/02; H03M1/08; H03M1/82
Domestic Patent References:
| JP421215A | ||||
| JP3104420A | ||||
| JP5327512A | ||||
| JP5335963A | ||||
| JP8154058A | ||||
| JP9186601A | ||||
| JP10308671A |
Attorney, Agent or Firm:
Koji Tsubouchi