| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit capable of suppressing fluctuations in the impedance due to a level change in a control signal. SOLUTION: The semiconductor integrated circuit is provided with a resonance type modulation circuit 1 and a DCFL (direct coupled FET logic) circuit 2. The DFCL circuit 2 includes a current source 11 and an FET 12 connected in series between a power terminal D and a ground terminal. Since a control signal input circuit 7 and the DCFL circuit 2 are connected in series between a drain terminal and a control signal input terminal E of a FET 3, even when a level of the control signal is changed, the gate impedance of the FET 12 in the DCFL circuit 2 is almost unchanged and the gate impedance has a high resistance. Thus, the resonance type modulation circuit is can easily be matched with the DCFL circuit 2 and a matching circuit can be configured with a simple circuit in which a 50-ohm resistor is added in parallel.
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