| 摘要 |
PURPOSE:To simplify the circuit constitution and to improve the frequency accuracy and stability, by controlling the depth of modulation independently of the center frequency. CONSTITUTION:The 1st and 2nd oscillation frequency controlling signals INCR and BIAS are inputted to the 1st input terminal of an adder 1 and a selector 3. An addition signal (a) of the adder 1 is inputted to the 2nd input terminal of the selector 3. When an overflow signal of the adder 1 is inputted to the selection terminal of the selector 3, the input at the 1st input terminal is selected and when no overflow signal exists, the input at the 2nd input terminal is selected and inputted to a register 2. The register 2 fetches a selection output signal (s) and holds when a clock signal comes to the register 2. Thus, the center oscillating frequency and the frequency modulation can independently be controlled with the signals INCR and BIAS. Thus, no multiplier is required, allowing to simplify the circuit constitution and to improve the frequency accuracy and stability. |
