WIDE BAND IQ MODULATOR WITH RC/ CARRIAGE RETURN CHARACTER AUTOMATION QUADRATURE NETWORK

摘要

PURPOSE: To generate the quadrature phase of equal amplitude over wide range frequencies by providing a quadrature phase network for responding to a control signal depending on frequency. CONSTITUTION: An RF signal 24 is impressed to CR/RC phase shift networks (NW) 48 and 49. The NW 48 and 49 respectively output quadrature phase shift signals ϕi67 and ϕq66 through CR/RC phase shifters 61 and 60 in response to analog control signals Vci50 and Vcq51. The signals ϕi and ϕq are inputted to a linear amplifier 52 and level signals Di55 and Dq59 are outputted by level detectors 55 and 58. The signals Di55 and Dq59 control the NW 48 and 49 so as to turn the difference of Di55 and Dq59 to zero through a servo system for driving the signals Vci50 and Vcq51. This control can be performed by impressing the signals Vci and Vcq to the gate of MESFET consisting of variable resistors Ri65 and Rq62 at the phase shifters 61 and 60. Thus, the quadrature phase shift of equal amplitude can be provided in spite of frequency.