Title:
CURRENT CONTROLLING CIRCUIT
Document Type and Number:
Japanese Patent JPS58140822
Kind Code:
A
Abstract:
PURPOSE:To control accurately the oscillating frequency and phase of a voltage control oscillating circuit, by deciding the increment and decrement of bias current with ratio of dimensions of transistors for a current controlling circuit which is suited to a voltage control oscillator of a PLL. CONSTITUTION:A switch MISFETQ3 to which a compensating signal Pc is supplied is provided in addition to a constant current source that supplies the bias current of a voltage control oscillating circuit 1. Usually the bias voltage which is a little higher than the threshold voltage of an MISFETQ1 is supplied to said MISFETQ1, and a constant current I is supplied to the circuit 1. When the signal Pc is supplied to the MISFETQ3, a current DELTAI flows to MISFETQ2 and Q3 to be supplied to the circuit 1. The ratio between currents I and DELTAI is decided by the ratio of dimensions between the MISFETQ1 and Q2. As a result, the frequency and phase of the circuit 1 can be accurately controlled.
Inventors:
FUJII FUMIAKI
Application Number:
JP2115682A
Publication Date:
August 20, 1983
Filing Date:
February 15, 1982
Export Citation:
Assignee:
HITACHI LTD
International Classes:
H03L7/099; G05F1/56; H03L7/08; (IPC1-7): G05F1/56; H03L7/06
Attorney, Agent or Firm:
Toshiyuki Usuda