Dual mode FM and DQPSK modulator

摘要: A dual-mode radiotelephone terminal includes a π/4-shift DQPSK modulator (11). modulation is achieved by mixing an output of transmitter oscillator (16) with offset (18) to form injection signal (LO) at final frequency, the being further modulated quadrature in digital mode operation. In analog operation or frequency and disabled bias signal, thereby passing without substantial attenuation. The LO regenerated also phase shifted circuit (35) having multiplier (30) divider (34). outputs two local signals (LOA LOB), each which directly drives associated mixer (36, 38) modulator. control employed for selectively enabling disabling various these components as function operating mode, conserving power.