Patent attributes
The 90-degree phase shifter of the invention has: a T flip-flop including transistors Q3 to Q6 and Q9 to Q12 that together constitute a dual differential circuit, input transistors Q1 and Q2 that receive at their bases an input signal, and input transistors Q7 and Q8 that receive at their bases a signal complementary to the input signal; variable current sources 14 to 17 connected respectively to the nodes between the individual input transistors and the dual differential circuit; and a 90-degree phase comparator 10 that compares the phase differences between the signals outputted from the T flip-flop to output signals commensurate with the deviations of those phase differences from 90 degrees. The variable current sources 14 to 17 are controlled by signals based on the signals outputted from the 90-degree phase comparator 10. This configuration more surely yields output signals with a phase difference of exactly 90 degrees.
