四毫米速调管模拟锁相环一般存在严重的缺点:由于四毫米速调管的推频系数和相位噪声较大,而模拟鉴相器的线性鉴相范围较小,使得环路难于入锁或鉴定不可靠。分析表明,数字鉴相鉴频器(D.P.F.D)有明显的优点:线性鉴相范围接近±2π,约为模拟鉴相器的2π倍,且具有鉴频功能。我们把它引入四毫米速调管环路中,使环路的捕捉带和同步带大增,环路容易入锁且锁定很可靠。我们研制的四毫米速调管数字鉴相锁相环采用的是超外差环方案。其原理方框图如图1 Four-millimeter klystrone analog phase-locked loop generally has serious shortcomings: Because the four-millimeter klystron has a large frequency-to-phase coefficient and phase noise, and the analog phase detector has a small range of phase-to-phase discrimination, making the loop difficult to lock Or identification is not reliable. Analysis shows that digital phase discriminator (D.P.F.D) has obvious advantages: the range of linear phase detector is close to ± 2π, which is about 2π times of analog phase detector, and has frequency discrimination function. We introduced it into the four millimeter klystron loop, which greatly increased the capture and timing belts of the loop, making it easy to lock the loop and lock it reliably. We developed a four-millimeter klyssel phase digital phase-locked loop using a super-heterodyne ring program. The principle block diagram shown in Figure 1