Differential logic circuit, frequency divider, and frequency synthesizer

Abstract

A differential logic circuit including a current source circuit which is connected to a current control terminal and generates a current, the current value is controlled by a signal received from the current control terminal, a differential unit which, based on the current from the current source circuit, inputs a plurality of logic signals, performs a logic operation, and outputs a result of the logic operation from a pair of differential signal output terminals thereof, a load circuit which is connected to the pair of differential signal output terminals, and a load control circuit which monitors a change of the current value and controls a load of the load circuit based on a result of the monitoring.

1 . A differential logic circuit comprising:
 a current source circuit which is connected to a current control terminal and generates a current, the current value is controlled by a signal received from the current control terminal;   a differential logic unit which, based on the current from the current source circuit, inputs a plurality of logic signals, performs a logic operation, and outputs a result of the logic operation from a pair of differential signal output terminals thereof;   a load circuit which is connected to the pair of differential signal output terminals; and   a load control circuit which monitors a change of the current value and controls a load of the load circuit based on a result of the monitoring.   
     
     
         2 . The differential logic circuit according to  claim 1 , wherein the load control circuit controls the load of the load circuit such that a direct-current output voltage of the pair of differential signal output terminals is constant.