Patent ID: 7474169

Claim:
An attenuator comprising: a first diode having an anode and a cathode that are connected to an input terminal and an output terminal, respectively; a first control voltage terminal connected to said anode of said first diode; a first capacitance; a second diode having an anode and a cathode, said anode being connected to said cathode of said first diode, said cathode of said second diode being connected to said anode of said first diode through said first capacitance; a first resistance connected at a first end to said cathode of said second diode; a second capacitance; a second resistance connected at a first end to said cathode of said first diode through said second capacitance; a third capacitance; a third diode having an anode and a cathode, said anode being connected to second ends of said first and second resistances through said third capacitance; a fourth capacitance; a fourth diode having an anode and a cathode, said cathode being connected to said second ends of said first and second resistances through said fourth capacitance; a fifth capacitance connected at a first end to said cathode of said third diode and to said anode of said fourth diode, a second end of said fifth capacitance being grounded; a second control voltage terminal connected to said cathode of said second diode; a third control voltage terminal connected to said anode of said third diode; a fourth control voltage terminal connected to said cathode of said fourth diode; and a linearizer provided between said input terminal and said anode of said first diode, wherein said linearizer linearizes a signal input to said input terminal only when low level voltages are applied to said first and fourth control voltage terminals at the same time that high level voltages are applied to said second and third control voltage terminals.