Title:
INTEGRATED CIRCUIT INCORPORATING OSCILLATOR
Document Type and Number:
Japanese Patent JPH01114121
Kind Code:
A
Abstract:
PURPOSE:To correct the oscillation frequency against a change in the operating environment such as variance at manufacture or temperature change by measuring the frequency of the oscillator periodically based on a basic clock and switching a capacitor corresponding to the measured value. CONSTITUTION:When an enable signal 3 goes to '1', a signal of a frequency decided by a resistor 4 and capacitors 7, 9 is given from an output 8 of the oscillator to a gate 13. When a gate time signal 22 of a gate time generator 21 goes to '1', the output 8 is inputted to a counter 14 and the frequency in measured. When the signal 22 reaches '0', the output of the counter 14 is latched by a latch 15 and a latch output signal 20 is compared with a preset value by a comparator circuit 16. In this case, when the signal 20 is larger than the setting value (the frequency is high), changeover signals 17, 18 go to '1' and transfer gates 10, 12 are conductive. As a result, capacitors 7, 9, 11 are connected in parallel, the capacitance between contacts (a), (b) is increased and the frequency of the output 8 is decreased.
Inventors:
MATSUBA NAOKI
Application Number:
JP27227487A
Publication Date:
May 02, 1989
Filing Date:
October 27, 1987
Export Citation:
Assignee:
NIPPON ELECTRIC IC MICROCOMPUT
International Classes:
H03L1/02; H03L7/06; H03L7/181; (IPC1-7): H03L1/02; H03L7/06
Attorney, Agent or Firm:
Uchihara Shin