| 摘要 |
PURPOSE:To form a carrier wave suppression circuit for a double balanced modulator which can decrease the amount of carrier wave leakage extremely, by using a variable resistor for an emitter resistor of one transistor constituting a constant current supply circuit of a balanced pair. CONSTITUTION:A signal P to be modulated is inputted to transistors (TR) Q5 and Q6 constituting a differential amplifying circuit of linear operation to the signal P to a double balanced modulator, a carrier wave C is inputted to a switch circuit consisting of TRs Q1-Q4, then the TRs Q1-Q4 are alternately turned on and off at each half wave of the carrier wave C to pick up a (C+ or -P) signal modulated from a transformer T. A variable resistor RV1 is used for a resistor of the emitter circuit of a TRQ8 out of TRs Q7, Q8 constituting a constant current source circuit and the value is changed to adjust the unbalace of the TRs Q7, Q8 and the modulation wave output transformer T. |
